我希望这是关于如何使用SQL语句检查SQL Server 2000/2005中是否存在表的最终讨论。
这里有两种可能的方法。哪一种是做这件事的标准/最佳方式?
第一个方法:
IF EXISTS (SELECT 1
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE='BASE TABLE'
AND TABLE_NAME='mytablename')
SELECT 1 AS res ELSE SELECT 0 AS res;
第二种方式:
IF OBJECT_ID (N'mytablename', N'U') IS NOT NULL
SELECT 1 AS res ELSE SELECT 0 AS res;
MySQL提供简单的
SHOW TABLES LIKE '%tablename%';
声明。我在找类似的东西。
当前回答
IF EXISTS (
SELECT *
FROM INFORMATION_SCHEMA.TABLES
WHERE
TABLE_CATALOG = 'Database Name' and
TABLE_NAME = 'Table Name' and
TABLE_SCHEMA = 'Schema Name') -- Database and Schema name in where statement can be deleted
BEGIN
--TABLE EXISTS
END
ELSE BEGIN
--TABLE DOES NOT EXISTS
END
其他回答
IF EXISTS (
SELECT *
FROM INFORMATION_SCHEMA.TABLES
WHERE
TABLE_CATALOG = 'Database Name' and
TABLE_NAME = 'Table Name' and
TABLE_SCHEMA = 'Schema Name') -- Database and Schema name in where statement can be deleted
BEGIN
--TABLE EXISTS
END
ELSE BEGIN
--TABLE DOES NOT EXISTS
END
-- -- create过程检查表是否存在
DELIMITER $$
DROP PROCEDURE IF EXISTS `checkIfTableExists`;
CREATE PROCEDURE checkIfTableExists(
IN databaseName CHAR(255),
IN tableName CHAR(255),
OUT boolExistsOrNot CHAR(40)
)
BEGIN
SELECT count(*) INTO boolExistsOrNot FROM information_schema.TABLES
WHERE (TABLE_SCHEMA = databaseName)
AND (TABLE_NAME = tableName);
END $$
DELIMITER ;
-- --如何使用:检查表迁移是否存在
CALL checkIfTableExists('muDbName', 'migrations', @output);
在我的记忆中，我们总是使用OBJECT_ID样式
IF OBJECT_ID('*objectName*', 'U') IS NOT NULL
我认为下面的查询是可行的:
IF EXISTS (select * from sys.tables
WHERE name='mytablename' )
BEGIN
print 'table exists in the database'
END
我以创建一个视图为例。
因为ALTER/CREATE命令不能在BEGIN/END块中。在创建之前，您需要测试是否存在并删除它
IF Object_ID('TestView') IS NOT NULL
DROP VIEW TestView
GO
CREATE VIEW TestView
as
. . .
GO
如果您担心权限丢失，您也可以编写GRANT语句，并在最后重新运行它们。
你可以把create/alter包装成一个字符串，然后执行EXEC——对于大的视图来说，这可能会很难看
DECLARE @SQL as varchar(4000)
-- set to body of view
SET @SQL = 'SELECT X, Y, Z FROM TABLE'
IF Object_ID('TestView') IS NULL
SET @SQL = 'CREATE VIEW TestView AS ' + @SQL
ELSE
SET @SQL = 'ALTER VIEW TestView AS ' + @SQL
