MySQL 在 PHP 中重命名列

Question

我需要使用 PHP 重命名 MySQL 表中的列。

这变得很困难，因为语法是 ALTER TABLE [table] CHANGE COLUMN [oldname] [newname] [definition]。该定义是必需的参数。

有没有办法获取定义并将其简单地反馈到 SQL 语句中？一些示例代码会很棒，谢谢！

Answer 1

根据 http://codingforums.com/showthread.php?t=148936，您可能必须解析 SHOW CREATE TABLE 的结果才能获取当前定义，然后在 ALTER 语句中使用它。

mysql_fetch_field() 也可能有用。

Answer 2

1. 您可以阅读information_schema。
   




2. 显示表状态 [{FROM | IN} db_name] [LIKE '模式' | WHERE 表达式]
   

Answer 3

发出 SHOW CREATE TABLE，读出描述感兴趣的列的行，识别列定义并构建您的 ALTER TABLE 语句。

Answer 4

我的解决方案是这样的：

$table = "tableName";
$createTableSQL = $dbh->Execute('SHOW CREATE TABLE ' . $table);
$createTableSQL = $createTableSQL[0][1];

$mappingTable = "originalToDevMapping";

//get mapping
$sql = "SELECT origField, newField
        FROM " . $mappingTable;
$newColumns = $dbh->Execute($sql);

foreach ($newColumns as $newColumn) {
    if (strlen($newColumn['newField'])<1) {
        echo "***Removing*** " . $newColumn['origField'] . "<br><br>";

        $sql = "ALTER TABLE " . $table . " DROP COLUMN " . $newColumn['origField'];

        $dbh->Execute($sql);
        if (strlen($dbh->errorStr)>1) {
            echo "<br>************************<br>";
            echo "<br>ERROR:<br>";
            echo $dbh->errorStr;
            echo "<br>************************<br>";
        }

    } else {
        echo "Renaming " .  $newColumn['origField'] . " to " . $newColumn['newField'] . "<br><br>";
        $sql = "ALTER TABLE " . $table . " CHANGE COLUMN " . $newColumn['origField'] . " " . $newColumn['newField'];
        $fieldPos = strpos($createTableSQL,$newColumn['origField']);
        $definitionStart = $fieldPos + strlen($newColumn['origField']) + 2;
        $definitionEnd = strpos($createTableSQL,',',$definitionStart) - 1;
        $definition = substr($createTableSQL,$definitionStart,$definitionEnd-$definitionStart+1);

        //workaround - if enum type, comma is included.  
        if (strstr($definition,'enum')) {
            //look for comma after enum end bracket.
            $commaPos = strpos($createTableSQL, ',', strpos($createTableSQL,')',$definitionStart));
            $definition = substr($createTableSQL,$definitionStart,$commaPos-$definitionStart);
        }

        $dbh->Execute($sql . " " . $definition);
        if (strlen($dbh->errorStr)>1) {
            echo "<br>************************<br>";
            echo "ERROR:<br>";
            echo $dbh->errorStr;
            echo "<br>************************<br>";
        }


    }

}