Question

我需要检查mytable表是否包含mycolumn列？这是我的疑问：

SELECT CASE WHEN EXISTS (SHOW COLUMNS FROM mytable LIKE mycolumn) THEN 1 ELSE 0 END;

但它不起作用并抛出此错误消息：

＃1064 - 您的SQL语法出错;检查与MySQL服务器版本对应的手册，以获得正确的语法在'mytable LIKE mycolumn'附近'SHOW COLUMNS'那么在第1行结束0结束

出了什么问题，如何解决？

Answer 1

您可以将以下内容用作if

IF EXISTS(
    select * from 
    INFORMATION_SCHEMA.COLUMNS
    WHERE TABLE_NAME ='SOMETABLE' AND
    COLUMN_NAME = 'SOMECOLUMN')
)   
BEGIN
     -- do stuff
END
GO

或者作为案例

SELECT CASE WHEN EXISTS(
    select * from 
    INFORMATION_SCHEMA.COLUMNS
    WHERE TABLE_NAME ='TABLE_NAME' AND
    COLUMN_NAME = 'COLUMN_NAME') 
Then 1 Else 0 End;

Answer 2

试试这个

SELECT CASE WHEN EXISTS (
  SELECT * FROM information_schema.COLUMNS 
    WHERE TABLE_SCHEMA = 'db_name' 
    AND TABLE_NAME = 'table_name' 
    AND COLUMN_NAME = 'column_name') 
then 1 
else 0 
end;

Answer 3

如果您需要动态传递表名和列名，请使用此名称。

DECLARE @Table Varchar(100)
DECLARE @Column Varchar(100)
DECLARE @Query nvarchar(max)

SET @Table ='MyTable'
SET @Column ='MyColumn'


SET @Query ='select * from 
    INFORMATION_SCHEMA.COLUMNS
    WHERE TABLE_NAME ='''+@Table+''' AND
    COLUMN_NAME IN ('''+@Column+''')'

EXEC (@Query)

如何检查表中是否存在列？

3 个答案: