MySQL的程序：如果列不存在，創建它

Question

我儘量讓創造在我的MySQL表不存在柱喜歡這裏的程序： MySQL add column if not exist

我的方法：

DELIMITER $$ 
CREATE PROCEDURE Alter_Table(IN _table_name TEXT,IN _column_name TEXT,IN _column_type TEXT) 
BEGIN 
    DECLARE _count INT; 
    SET _count = ( SELECT COUNT(*) 
        FROM INFORMATION_SCHEMA.COLUMNS 
        WHERE TABLE_NAME = _table_name AND 
          COLUMN_NAME = _column_name); 
    IF _count = 0 THEN 
     ALTER TABLE _table_name ADD COLUMN _column_name _column_type; 
    END IF; 
END $$ 
DELIMITER ; 

但是我有一個錯誤：

#1064 - Something is wrong in your syntax obok '_column_type; END IF; END' w linii 9 

任何人都知道爲什麼？

Answer 1

好吧......我讓它在PHP ...

function alter_table($table_name, $column_name, $column_type) { 
    $result = mysql_query("SELECT * FROM INFORMATION_SCHEMA.COLUMNS 
       WHERE TABLE_NAME = `$table_name` AND COLUMN_NAME = `$column_name`"); 
    if(!$result) { 
     mysql_query("ALTER TABLE `$table_name` 
      ADD COLUMN `$column_name` $column_type"); 
    } 
}