Question

如果在MySQL中不存在，如何添加列？

我试过这个，但它在最新的MySQL中不再起作用了：

[Err] 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF NOT EXISTS (
    SELECT
        NULL
    FROM
        INFORMATION_SCHEMA.COLUMNS
    WHERE
    ' at line 1

错误：

  <?php
    $rfp = \app\models\RfpMeta::find()->where(['rfp_id' => $rfp_id])->all();

    ?>

<div style="display: inline-block;
     width: 85%;
     margin: 10px;
     border: 1px solid #ccc;
     ">
    <div style="width: 100%;*zoom: 1;">
        <div style="padding: 15px 5px;height: 65px;width: auto;background-color: #3398d4;">

        </div>
    </div>
    <div style="margin: 5px;"></div>
    <div style="width: 100%;*zoom: 1;">
        <div style="margin:10px 0;padding: 5px;">
            <span style="margin-top:20px;margin-bottom:10px;font-family:inherit;font-weight:bold;line-height:1.1;color:#444;font-size: 18px;"> Request For Proposal</span><br><br>
        </div>
    </div>
    <div style="width: 100%;*zoom: 1;">
        <div style="padding: 5px;">
             <p  class="text-center" style="text-align:justify">Subject : <?php echo $subject;
                                                ?></p>
                                                <br/>
            <p style="text-align:justify;">Dear <?php 
                                              foreach ($model as $key ) {
                                                 echo  $key ." ". "/" ;                                              }
                                                ?>,</p> <br/>
            <p style="text-align:justify;"> <?php echo $message ?><br>


          <table class="table table-hover table-striped table-bordered table-condensed">
            <thead>
                   <tr>
                    <th class="text-center">Item</th>
                    <th class="text-center">Quantity</th>
                    <th class="text-center">Unit</th>
                </tr>
            </thead>
            <?php
             foreach ($rfp as $each) {
                    $typ = $each->type;
                   if ($typ == 1)
               {
               $model = \app\models\RawMaster::findOne(['id'=>$each['item']])->raw_name;


               }
               elseif ($typ ==2)
               {
               $model = \app\models\AssetMaster::findOne(['id'=>$each['item']])->asset_name;
               }
               elseif ($typ == 3) {
             $model = \app\models\MachineMaster::findOne(['id'=>$each['item']])->name;
               }

                ?>
            <tbody>
              <tr>
                <td> <?= $model;?></td>
                <td><?= $each['qty']?></td>
                <td><?= $each['unit'] ?></td>
            </tr> 

        </tbody>
        <?php }
        ?>
    </table>

     <p style="text-align:justify;">
                Thank you.<br>
            </p>
        </div>
    </div>
    <div style="width: 100%;*zoom: 1;">
        <div style="padding: 5px;">
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        </div>
    </div>

</div>
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Answer 1

您得到该错误的唯一原因是您尝试单独运行它，而IF块必须在如下所示的过程块中执行

create procedure usp_addcol
as
begin
IF NOT EXISTS( SELECT NULL
            FROM INFORMATION_SCHEMA.COLUMNS
           WHERE table_name = 'tablename'
             AND table_schema = 'db_name'
             AND column_name = 'columnname')  THEN

  ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0';

END IF;
end;

现在您可以调用该过程。

MySQL添加列如果不存在错误

1 个答案: