PROSAGA码农传奇-Xedge-使用表连接丢失了对INFORMATION

使用表连接丢失了对INFORMATION_SCHEMA.COLUMNS表的查询

作者: 诸葛神侯
发布时间: 2024-08-19 07:01:51 (5天前)
转自：

<div class =“post-text”itemprop =“text”>
  <P>
    你的问题是由
     <code>
      GROUP BY
    </code>
     条款选择
     <code>
      DATA_TYPE
    </code>
     随机退出多个值，因为你的条件没有
     <code>
      JOIN
    </code>
    。您需要做的是通过向您的条件添加条件将每列名称的值数限制为1
     <code>
      JOIN
    </code>
    ：
  </p>
   <pre>
    <code>
      SELECT A.DATA_TYPE, B.INDEX_NAME, B.COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS AS A
JOIN INFORMATION_SCHEMA.STATISTICS AS B
ON A.TABLE_SCHEMA = B.TABLE_SCHEMA AND
   A.TABLE_NAME = B.TABLE_NAME AND
   A.COLUMN_NAME = B.COLUMN_NAME
WHERE A.TABLE_SCHEMA= "mySchema" AND 
      A.TABLE_NAME  = "myTable"

</code>
  </pre>
  <P>
    在PHP中（使用MySQLI）：
  </p>
   <pre>
    <code>
      $sql = 'SELECT A.DATA_TYPE, B.INDEX_NAME, B.COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS AS A
JOIN INFORMATION_SCHEMA.STATISTICS AS B
ON A.TABLE_SCHEMA = B.TABLE_SCHEMA AND
   A.TABLE_NAME = B.TABLE_NAME AND
   A.COLUMN_NAME = B.COLUMN_NAME
WHERE A.TABLE_SCHEMA= "mySchema" AND 
      A.TABLE_NAME  = "myTable"';
$result = mysqli_query($conn, $sql);
echo mysqli_num_rows($result);
while ($row = mysqli_fetch_assoc($result)) print_r($row);

</code>
  </pre>
</DIV>