Delphi使用ADO进行数据库编程
<p>Delphi是一个可视化的编程工具，ADO编程也是这样，所以话不多言，直接通过代码、截图和语言来说明。</p><p> 我的数据库是Oracle，为了测试，先建一个表：create table practice(uno varchar(8), uname varchar(20)); 这个表比较简单，只有两个字段。</p>
<p> 我的Oracle数据库是安装在虚拟机上的（操作系统是Redhat），所以需要先在服务器上配置好，另外需要在Windows上进行相关的配置（监听程序配置和本地网络服务名配置）。否则后面就没有办法配置数据源……来连接数据库。具体怎么进行配置请自己上网搜索查询。</p>
<p> 然后我们来做一个简单的增删改查的小工具。</p>
<p><strong>1.新建一个项目，上面放好需要控件 </strong></p>
<p> 如下图，其中最为重要的一个控件是用红框框起来的控件：TADOConnection</p>
<p><img src="https://images0.cnblogs.com/blog2015/711741/201508/252157448597021.png"></p>
<p> 注意需要引入DB、ADODB这两个单元。</p>
<p><strong>2.双击TADOConnection控件进行配置 </strong></p>
<p> 双击TADOConnection打开</p>
<p><img src="https://images0.cnblogs.com/blog2015/711741/201508/252200122651389.png"></p>
<p> 点击Build..按钮，先选择数据库驱动，我选择的是最后一个</p>
<p><img src="https://images0.cnblogs.com/blog2015/711741/201508/252201166727465.png"></p>
<p> 像我使用的是Oracle数据库，所以需要选择Oracle的数据库驱动，这里面提供的Oracle数据库驱动有两种（Oracle自己的驱动还有微软提供的Oracle驱动），如下图用红框标记的</p>
<p><img src="https://images2015.cnblogs.com/blog/711741/201508/711741-20150829103203187-269819600.png"></p>
<p> 点击下一步，配置数据源，用户名密码等信息，选择允许保存密码，点击确定</p>
<p><img src="https://images0.cnblogs.com/blog2015/711741/201508/252202388904883.png"></p>
<p> 然后点击OK即可进行 下一步的编程工作</p>
<p><img src="https://images0.cnblogs.com/blog2015/711741/201508/252204057506118.png"></p>
<p><strong>3.然后实增删改查的功能 <br></strong></p>
<p><strong>首先是在响应窗体创建事件的函数中打开TADOConnection对象con1</strong></p>
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<div class="line number1 index0 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">FormCreate(Sender: TObject);</code></div>
<div class="line number2 index1 alt1"><code class="delphi keyword">begin</code></div>
<div class="line number3 index2 alt2"><code class="delphi spaces"> </code><code class="delphi plain">con1</code><code class="delphi value">.</code><code class="delphi plain">Open; </code></div>
<div class="line number4 index3 alt1"><code class="delphi keyword">end</code><code class="delphi plain">; </code></div>
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<p> 这里不需要调用con1.Create，因为通过将控件直接拖拽到窗体上的方式，会在窗体创建的时候也创建这些控件，如果这里在Create就会重复创建，重复创建就会出错。</p>
<p> </p>
<p><strong>接着是实现 “增” 的功能双击设计面板上的按钮，编写按钮响应OnClick的方法</strong></p>
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<div class="line number1 index0 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn1Click(Sender: TObject);</code></div>
<div class="line number2 index1 alt1"><code class="delphi keyword">var</code></div>
<div class="line number3 index2 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery: TADOQuery;</code></div>
<div class="line number4 index3 alt1"><code class="delphi spaces"> </code><code class="delphi plain">count: </code><code class="delphi keyword">Integer</code><code class="delphi plain">;</code></div>
<div class="line number5 index4 alt2"><code class="delphi keyword">begin</code></div>
<div class="line number6 index5 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number7 index6 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number8 index7 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text := </code><code class="delphi string">'INSERT INTO practice VALUES('</code><code class="delphi string">''</code> <code class="delphi plain">+ edt1</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">', '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt2</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">')'</code><code class="delphi plain">;</code></div>
<div class="line number9 index8 alt2"><code class="delphi spaces"> </code><code class="delphi plain">count:= adoQuery</code><code class="delphi value">.</code><code class="delphi plain">ExecSQL;</code></div>
<div class="line number10 index9 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">if</code><code class="delphi plain">(count></code><code class="delphi value">0</code><code class="delphi plain">) </code><code class="delphi keyword">then</code></div>
<div class="line number11 index10 alt2"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'成功插入'</code> <code class="delphi plain">+IntToStr(count) + </code><code class="delphi string">' 条数据'</code><code class="delphi plain">);</code></div>
<div class="line number12 index11 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number13 index12 alt2"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
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<p> 注意其中的代码的一些细节。</p>
<p> 将adoQuery的Connection属性设置为con1。</p>
<p> 拼接SQL的时候，注意两个单引号 ''的使用规范。</p>
<p> 对于往数据库中写数据的SQL，需要使用ExecSQL方法，insert、delete、update这样的写数据库的方法，需要调用ExecSQL方法，ExecSQL方法的返回值是这条SQL影响了数据库中的几条记录（比如：插入了几条记录、删除了几条记录、修改了几条记录），所以这个方法中会用到ExecSQL的返回值。</p>
<p> 最后不要忘了释放adoQuery对象。保证不会出现内存泄露，因为如果不释放，那么每次点击按钮就会创建一个adoQuery对象。不过这样使用局部变量也不是很好，可以使用TADDOQuery创建一个全局变量，在程序打开的时候创建好，做好Connection属性的赋值，然后使用，最后使用完成在程序关闭的时候再释放，这样就可以防止每次点击按钮都要创建，不过使用TADOQuery全局变量也要有一些规范，参见下面的总结说明！</p>
<p> </p>
<p><strong>补充说明TADOQuery</strong></p>
<p> 要想执行SQL需要创建TADOQuery对象。我们可以将AdoQuery作为一个局部变量，然后这个小demo中需要实现的增删改查每个都创建自己的TADOQuery局部变量，执行完之后再Free，当然也可以创建全局变量，然后每个操作都使用这个全局变量。</p>
<p> 但是如果使用全局变量的话，特别需要注意一点。在原来的使用TADOQuery局部变量的时候，每个操作之前先创建一个TADOQuery对象，然后将其Connection属性赋值为那个TADOConnection的变量，然后给SQL.Text赋值，然后就可以Open或者ExecSQL执行了，最后在程序结束的时候在进行Free即可。</p>
<p> 但是如果使用TADOQuery全局变量的话，首先是Create好TADOQuery，然后给它的Connection赋好值，然后每个操作的时候，直接将其SQL.Text赋值，然后执行就好了。不过在这个过程中必须注意在给SQL.Text赋值之前需要执行TADOQuery的Close方法，然后再SQL.Clear，然后再赋值SQL，然后再执行。</p>
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<div class="line number1 index0 alt2"><code class="delphi keyword">begin</code></div>
<div class="line number2 index1 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoquery</code><code class="delphi value">.</code><code class="delphi plain">close;</code></div>
<div class="line number3 index2 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoquery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">clear;</code></div>
<div class="line number4 index3 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoquery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">add(</code><code class="delphi string">'...'</code><code class="delphi plain">);</code></div>
<div class="line number5 index4 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoquery</code><code class="delphi value">.</code><code class="delphi plain">open; </code><code class="delphi comments">//如果是写操作的话就是adoquery.ExecSQL;</code></div>
<div class="line number6 index5 alt1"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
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<p> 这是一个经典的语句，在每次查询之前先把上次删除给关了。 如果不关，第一次查询是没问题的，可如果adoqury1再用一次的话，就会有可能和上次发生冲突。 程序的不确定性很强，所以这样做是有必要的，防止出现意想不到的问题。</p>
<p> <strong>Close还是需要。</strong>还有一点就是节约内存，用过就关，不然会一直呆在内存里面！！所以不管是使用adoquery.SQL.Text 还是adoquery.SQL.Add()，如果是全局变量的话，还是要使用Close方法。</p>
<p> <strong>Clear看情况决定要不要。</strong>不过如果是直接给adoquery.SQL.Text赋值的话，可以不用执行adoquery.SQL.Clear因为新赋的值将会覆盖原来的值。但是如果是使用adoquery.SQL.Add()的话，是在原来的SQL基础上追加，所以可能需要Clear原来的SQL，再添加新的SQL，保证可以不和上次冲突！</p>
<p><strong>再补充说明adoquery.SQL.Add和adoquery.SQL.Text的区别</strong></p>
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<div class="line number1 index0 alt2"><code class="delphi comments">//adoquery1.sql.add相当于添加一个值比如说</code></div>
<div class="line number2 index1 alt1"><code class="delphi plain">adoquery1</code><code class="delphi value">.</code><code class="delphi plain">sql</code><code class="delphi value">.</code><code class="delphi plain">text:=</code><code class="delphi string">'a'</code><code class="delphi plain">;</code></div>
<div class="line number3 index2 alt2"><code class="delphi plain">adoquery1</code><code class="delphi value">.</code><code class="delphi plain">sql</code><code class="delphi value">.</code><code class="delphi plain">add(</code><code class="delphi string">'b'</code><code class="delphi plain">);</code></div>
<div class="line number4 index3 alt1"> </div>
<div class="line number5 index4 alt2"><code class="delphi comments">//那么就相当于直接</code></div>
<div class="line number6 index5 alt1"><code class="delphi plain">adoquery1</code><code class="delphi value">.</code><code class="delphi plain">sql</code><code class="delphi value">.</code><code class="delphi plain">text=</code><code class="delphi string">'ab'</code><code class="delphi plain">;</code></div>
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<p> adoquery1.sql.text 就是说写一行完整的查询语句放在SQl的查询里。当在delphi中SQL语句太长，我们可以把adoquery1.sql.text 分开由多个adoquery1.sql.add()来分段写。</p>
<p> adoquery1.sql.add()主要起追加的作用。</p>
<p> </p>
<p><strong>接着实现 “查” 的功能，同样编写按钮响应OnClick的方法</strong></p>
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<div class="line number1 index0 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn2Click(Sender: TObject);</code></div>
<div class="line number2 index1 alt1"><code class="delphi keyword">var</code></div>
<div class="line number3 index2 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery: TADOQuery;</code></div>
<div class="line number4 index3 alt1"><code class="delphi keyword">begin</code></div>
<div class="line number5 index4 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number6 index5 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number7 index6 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text := </code><code class="delphi string">'SELECT * FROM practice WHERE uno = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt3</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">''</code><code class="delphi plain">;</code></div>
<div class="line number8 index7 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Open;</code></div>
<div class="line number9 index8 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">First;</code></div>
<div class="line number10 index9 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">while</code> <code class="delphi keyword">not</code> <code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Eof </code><code class="delphi keyword">do</code></div>
<div class="line number11 index10 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">begin</code></div>
<div class="line number12 index11 alt1"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(adoQuery</code><code class="delphi value">.</code><code class="delphi plain">fieldByName(</code><code class="delphi string">'uno'</code><code class="delphi plain">).AsString + </code><code class="delphi string">': '</code> <code class="delphi plain">+ adoQuery</code><code class="delphi value">.</code><code class="delphi plain">fieldByName(</code><code class="delphi string">'uname'</code><code class="delphi plain">).AsString);</code></div>
<div class="line number13 index12 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Next;</code></div>
<div class="line number14 index13 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number15 index14 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number16 index15 alt1"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
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<p> 执行Select的SQL，需要使用Open，而不是ExecSQL方法。</p>
<p> 通过判断Eof来进行循环展示搜索到的数据库中的符合条件的记录。判断是否Eof，注意Eof为True并不是指向了最后一条记录的时候，而是指向了最后一条记录之后，再Next时Eof才是True。</p>
<p> First是定位到所有搜索到的记录的第一条。Next是指向下一条。</p>
<p> 根据字段名称获取每条记录的对应信息，注意这里面使用FieldByName获取字段对应的值的方法。因为前面是使用的select * from，所以可以既获得'uno'，有可以获得'uname'，假如用select uname from 的话，就只能使用fieldByName获得'uname'，不能获得'uno'，所以使用fieldByName时候需要注意select语句搜索了哪几项。</p>
<p> </p>
<p><strong>接下来讲解删除功能的代码</strong></p>
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<div class="line number1 index0 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn3Click(Sender: TObject);</code></div>
<div class="line number2 index1 alt1"><code class="delphi keyword">var</code></div>
<div class="line number3 index2 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery: TADOQuery;</code></div>
<div class="line number4 index3 alt1"><code class="delphi spaces"> </code><code class="delphi plain">count: </code><code class="delphi keyword">Integer</code><code class="delphi plain">;</code></div>
<div class="line number5 index4 alt2"><code class="delphi keyword">begin</code></div>
<div class="line number6 index5 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number7 index6 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number8 index7 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text := </code><code class="delphi string">'DELETE FROM practice WHERE uno = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt4</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">''</code><code class="delphi plain">;</code></div>
<div class="line number9 index8 alt2"><code class="delphi spaces"> </code><code class="delphi plain">count:= adoQuery</code><code class="delphi value">.</code><code class="delphi plain">ExecSQL;</code></div>
<div class="line number10 index9 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">if</code> <code class="delphi plain">count></code><code class="delphi value">0</code> <code class="delphi keyword">then</code></div>
<div class="line number11 index10 alt2"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'删除'</code> <code class="delphi plain">+ IntToStr(count) + </code><code class="delphi string">' 条数据'</code><code class="delphi plain">)</code></div>
<div class="line number12 index11 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">else</code></div>
<div class="line number13 index12 alt2"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'没有删除数据'</code><code class="delphi plain">);</code></div>
<div class="line number14 index13 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number15 index14 alt2"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
</div>
</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<p> </p>
<p> </p>
<p><strong>最后是改数据库数据的功能代码</strong></p>
<div class="cnblogs_Highlighter sh-gutter">
<div>
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<div class="line number1 index0 alt2">1</div>
<div class="line number2 index1 alt1">2</div>
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<div class="line number5 index4 alt2">5</div>
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<div class="line number12 index11 alt1">12</div>
</td>
<td class="code">
<div class="container">
<div class="line number1 index0 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn4Click(Sender: TObject);</code></div>
<div class="line number2 index1 alt1"><code class="delphi keyword">var</code></div>
<div class="line number3 index2 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoquery: TADOQuery;</code></div>
<div class="line number4 index3 alt1"><code class="delphi spaces"> </code><code class="delphi plain">count: </code><code class="delphi keyword">Integer</code><code class="delphi plain">;</code></div>
<div class="line number5 index4 alt2"><code class="delphi keyword">begin</code></div>
<div class="line number6 index5 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number7 index6 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number8 index7 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoquery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text:= </code><code class="delphi string">'UPDATE practice SET uname = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt6</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">'WHERE uno = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt5</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">''</code><code class="delphi plain">;</code></div>
<div class="line number9 index8 alt2"><code class="delphi spaces"> </code><code class="delphi plain">count:= adoquery</code><code class="delphi value">.</code><code class="delphi plain">ExecSQL;</code></div>
<div class="line number10 index9 alt1"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'修改了'</code> <code class="delphi plain">+ IntToStr(count) + </code><code class="delphi string">' 条记录'</code><code class="delphi plain">);</code></div>
<div class="line number11 index10 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number12 index11 alt1"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
</div>
</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<p> </p>
<p> </p>
<p><strong>最后的代码是 </strong></p>
<div class="cnblogs_Highlighter sh-gutter">
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</td>
<td class="code">
<div class="container">
<div class="line number1 index0 alt2"><code class="delphi keyword">unit</code> <code class="delphi plain">Unit1;</code></div>
<div class="line number2 index1 alt1"> </div>
<div class="line number3 index2 alt2"><code class="delphi keyword">interface</code></div>
<div class="line number4 index3 alt1"> </div>
<div class="line number5 index4 alt2"><code class="delphi keyword">uses</code></div>
<div class="line number6 index5 alt1"><code class="delphi spaces"> </code><code class="delphi plain">Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,</code></div>
<div class="line number7 index6 alt2"><code class="delphi spaces"> </code><code class="delphi plain">Dialogs, StdCtrls, DB, ADODB;</code></div>
<div class="line number8 index7 alt1"> </div>
<div class="line number9 index8 alt2"><code class="delphi keyword">type</code></div>
<div class="line number10 index9 alt1"><code class="delphi spaces"> </code><code class="delphi plain">TForm1 = </code><code class="delphi keyword">class</code><code class="delphi plain">(TForm)</code></div>
<div class="line number11 index10 alt2"><code class="delphi spaces"> </code><code class="delphi plain">con1: TADOConnection;</code></div>
<div class="line number12 index11 alt1"><code class="delphi spaces"> </code><code class="delphi plain">edt1: TEdit;</code></div>
<div class="line number13 index12 alt2"><code class="delphi spaces"> </code><code class="delphi plain">lbl1: TLabel;</code></div>
<div class="line number14 index13 alt1"><code class="delphi spaces"> </code><code class="delphi plain">edt2: TEdit;</code></div>
<div class="line number15 index14 alt2"><code class="delphi spaces"> </code><code class="delphi plain">lbl2: TLabel;</code></div>
<div class="line number16 index15 alt1"><code class="delphi spaces"> </code><code class="delphi plain">btn1: TButton;</code></div>
<div class="line number17 index16 alt2"><code class="delphi spaces"> </code><code class="delphi plain">edt3: TEdit;</code></div>
<div class="line number18 index17 alt1"><code class="delphi spaces"> </code><code class="delphi plain">lbl3: TLabel;</code></div>
<div class="line number19 index18 alt2"><code class="delphi spaces"> </code><code class="delphi plain">btn2: TButton;</code></div>
<div class="line number20 index19 alt1"><code class="delphi spaces"> </code><code class="delphi plain">edt4: TEdit;</code></div>
<div class="line number21 index20 alt2"><code class="delphi spaces"> </code><code class="delphi plain">lbl4: TLabel;</code></div>
<div class="line number22 index21 alt1"><code class="delphi spaces"> </code><code class="delphi plain">btn3: TButton;</code></div>
<div class="line number23 index22 alt2"><code class="delphi spaces"> </code><code class="delphi plain">edt5: TEdit;</code></div>
<div class="line number24 index23 alt1"><code class="delphi spaces"> </code><code class="delphi plain">lbl5: TLabel;</code></div>
<div class="line number25 index24 alt2"><code class="delphi spaces"> </code><code class="delphi plain">edt6: TEdit;</code></div>
<div class="line number26 index25 alt1"><code class="delphi spaces"> </code><code class="delphi plain">lbl6: TLabel;</code></div>
<div class="line number27 index26 alt2"><code class="delphi spaces"> </code><code class="delphi plain">btn4: TButton;</code></div>
<div class="line number28 index27 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">procedure</code> <code class="delphi plain">FormCreate(Sender: TObject);</code></div>
<div class="line number29 index28 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">procedure</code> <code class="delphi plain">btn1Click(Sender: TObject);</code></div>
<div class="line number30 index29 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">procedure</code> <code class="delphi plain">btn2Click(Sender: TObject);</code></div>
<div class="line number31 index30 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">procedure</code> <code class="delphi plain">btn3Click(Sender: TObject);</code></div>
<div class="line number32 index31 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">procedure</code> <code class="delphi plain">btn4Click(Sender: TObject);</code></div>
<div class="line number33 index32 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">private</code></div>
<div class="line number34 index33 alt1"><code class="delphi spaces"> </code><code class="delphi comments">{ Private declarations }</code></div>
<div class="line number35 index34 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">public</code></div>
<div class="line number36 index35 alt1"><code class="delphi spaces"> </code><code class="delphi comments">{ Public declarations }</code></div>
<div class="line number37 index36 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number38 index37 alt1"> </div>
<div class="line number39 index38 alt2"><code class="delphi keyword">var</code></div>
<div class="line number40 index39 alt1"><code class="delphi spaces"> </code><code class="delphi plain">Form1: TForm1;</code></div>
<div class="line number41 index40 alt2"> </div>
<div class="line number42 index41 alt1"><code class="delphi keyword">implementation</code></div>
<div class="line number43 index42 alt2"> </div>
<div class="line number44 index43 alt1"><code class="delphi color1">{$R *.dfm}</code></div>
<div class="line number45 index44 alt2"> </div>
<div class="line number46 index45 alt1"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">FormCreate(Sender: TObject);</code></div>
<div class="line number47 index46 alt2"><code class="delphi keyword">begin</code></div>
<div class="line number48 index47 alt1"><code class="delphi spaces"> </code><code class="delphi plain">con1</code><code class="delphi value">.</code><code class="delphi plain">Open;</code></div>
<div class="line number49 index48 alt2"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number50 index49 alt1"> </div>
<div class="line number51 index50 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn1Click(Sender: TObject);</code></div>
<div class="line number52 index51 alt1"><code class="delphi keyword">var</code></div>
<div class="line number53 index52 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery: TADOQuery;</code></div>
<div class="line number54 index53 alt1"><code class="delphi spaces"> </code><code class="delphi plain">count: </code><code class="delphi keyword">Integer</code><code class="delphi plain">;</code></div>
<div class="line number55 index54 alt2"><code class="delphi keyword">begin</code></div>
<div class="line number56 index55 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number57 index56 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number58 index57 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text := </code><code class="delphi string">'INSERT INTO practice VALUES('</code><code class="delphi string">''</code> <code class="delphi plain">+ edt1</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">', '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt2</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">')'</code><code class="delphi plain">;</code></div>
<div class="line number59 index58 alt2"><code class="delphi spaces"> </code><code class="delphi plain">count:= adoQuery</code><code class="delphi value">.</code><code class="delphi plain">ExecSQL;</code></div>
<div class="line number60 index59 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">if</code><code class="delphi plain">(count></code><code class="delphi value">0</code><code class="delphi plain">) </code><code class="delphi keyword">then</code></div>
<div class="line number61 index60 alt2"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'成功插入'</code> <code class="delphi plain">+IntToStr(count) + </code><code class="delphi string">' 条数据'</code><code class="delphi plain">);</code></div>
<div class="line number62 index61 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number63 index62 alt2"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number64 index63 alt1"> </div>
<div class="line number65 index64 alt2"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn2Click(Sender: TObject);</code></div>
<div class="line number66 index65 alt1"><code class="delphi keyword">var</code></div>
<div class="line number67 index66 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery: TADOQuery;</code></div>
<div class="line number68 index67 alt1"><code class="delphi keyword">begin</code></div>
<div class="line number69 index68 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number70 index69 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number71 index70 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text := </code><code class="delphi string">'SELECT * FROM practice WHERE uno = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt3</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">''</code><code class="delphi plain">;</code></div>
<div class="line number72 index71 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Open;</code></div>
<div class="line number73 index72 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">First;</code></div>
<div class="line number74 index73 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">while</code> <code class="delphi keyword">not</code> <code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Eof </code><code class="delphi keyword">do</code></div>
<div class="line number75 index74 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">begin</code></div>
<div class="line number76 index75 alt1"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(adoQuery</code><code class="delphi value">.</code><code class="delphi plain">fieldByName(</code><code class="delphi string">'uno'</code><code class="delphi plain">).AsString + </code><code class="delphi string">': '</code> <code class="delphi plain">+ adoQuery</code><code class="delphi value">.</code><code class="delphi plain">fieldByName(</code><code class="delphi string">'uname'</code><code class="delphi plain">).AsString);</code></div>
<div class="line number77 index76 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Next;</code></div>
<div class="line number78 index77 alt1"><code class="delphi spaces"> </code><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number79 index78 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number80 index79 alt1"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number81 index80 alt2"> </div>
<div class="line number82 index81 alt1"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn3Click(Sender: TObject);</code></div>
<div class="line number83 index82 alt2"><code class="delphi keyword">var</code></div>
<div class="line number84 index83 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery: TADOQuery;</code></div>
<div class="line number85 index84 alt2"><code class="delphi spaces"> </code><code class="delphi plain">count: </code><code class="delphi keyword">Integer</code><code class="delphi plain">;</code></div>
<div class="line number86 index85 alt1"><code class="delphi keyword">begin</code></div>
<div class="line number87 index86 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number88 index87 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number89 index88 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text := </code><code class="delphi string">'DELETE FROM practice WHERE uno = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt4</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">''</code><code class="delphi plain">;</code></div>
<div class="line number90 index89 alt1"><code class="delphi spaces"> </code><code class="delphi plain">count:= adoQuery</code><code class="delphi value">.</code><code class="delphi plain">ExecSQL;</code></div>
<div class="line number91 index90 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">if</code> <code class="delphi plain">count></code><code class="delphi value">0</code> <code class="delphi keyword">then</code></div>
<div class="line number92 index91 alt1"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'删除'</code> <code class="delphi plain">+ IntToStr(count) + </code><code class="delphi string">' 条数据'</code><code class="delphi plain">)</code></div>
<div class="line number93 index92 alt2"><code class="delphi spaces"> </code><code class="delphi keyword">else</code></div>
<div class="line number94 index93 alt1"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'没有删除数据'</code><code class="delphi plain">);</code></div>
<div class="line number95 index94 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number96 index95 alt1"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number97 index96 alt2"> </div>
<div class="line number98 index97 alt1"><code class="delphi keyword">procedure</code> <code class="delphi plain">TForm1</code><code class="delphi value">.</code><code class="delphi plain">btn4Click(Sender: TObject);</code></div>
<div class="line number99 index98 alt2"><code class="delphi keyword">var</code></div>
<div class="line number100 index99 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoquery: TADOQuery;</code></div>
<div class="line number101 index100 alt2"><code class="delphi spaces"> </code><code class="delphi plain">count: </code><code class="delphi keyword">Integer</code><code class="delphi plain">;</code></div>
<div class="line number102 index101 alt1"><code class="delphi keyword">begin</code></div>
<div class="line number103 index102 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery := TADOQuery</code><code class="delphi value">.</code><code class="delphi plain">Create(</code><code class="delphi keyword">nil</code><code class="delphi plain">);</code></div>
<div class="line number104 index103 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Connection := con1;</code></div>
<div class="line number105 index104 alt2"><code class="delphi spaces"> </code><code class="delphi plain">adoquery</code><code class="delphi value">.</code><code class="delphi plain">SQL</code><code class="delphi value">.</code><code class="delphi plain">Text:= </code><code class="delphi string">'UPDATE practice SET uname = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt6</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">'WHERE uno = '</code><code class="delphi string">''</code> <code class="delphi plain">+ edt5</code><code class="delphi value">.</code><code class="delphi plain">Text + </code><code class="delphi string">''</code><code class="delphi string">''</code><code class="delphi plain">;</code></div>
<div class="line number106 index105 alt1"><code class="delphi spaces"> </code><code class="delphi plain">count:= adoquery</code><code class="delphi value">.</code><code class="delphi plain">ExecSQL;</code></div>
<div class="line number107 index106 alt2"><code class="delphi spaces"> </code><code class="delphi plain">ShowMessage(</code><code class="delphi string">'修改了'</code> <code class="delphi plain">+ IntToStr(count) + </code><code class="delphi string">' 条记录'</code><code class="delphi plain">);</code></div>
<div class="line number108 index107 alt1"><code class="delphi spaces"> </code><code class="delphi plain">adoQuery</code><code class="delphi value">.</code><code class="delphi plain">Free;</code></div>
<div class="line number109 index108 alt2"><code class="delphi keyword">end</code><code class="delphi plain">;</code></div>
<div class="line number110 index109 alt1"> </div>
<div class="line number111 index110 alt2"><code class="delphi keyword">end</code><code class="delphi plain">.</code></div>
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来源：https://www.cnblogs.com/yerongtian/p/11141015.html
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