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
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
其他回答
为了开发人员和其他dba的利益，这里只是添加了一些内容
接收@Tablename作为参数的脚本
(可能包含也可能不包含模式名)并返回下面的信息。表存在:
the_name object_id the_schema the_table the_type
[Facts].[FactBackOrder] 758293761 Facts FactBackOrder Table
我制作了这个脚本，以便在每次需要测试表或视图是否存在时在其他脚本中使用，当它存在时，获取它的object_id用于其他目的。
当您传递了空字符串、错误的模式名或错误的表名时，将引发错误。
例如，它可以在过程中返回-1。
例如，我有一个名为“事实”的表格。在我的数据仓库数据库之一的FactBackOrder。
我是这样做到的:
PRINT 'THE SERVER IS ' + @@SERVERNAME
--select db_name()
PRINT 'THE DATABASE IS ' + db_NAME()
PRINT ''
GO
SET NOCOUNT ON
GO
--===================================================================================
-- @TableName is the parameter
-- the object we want to deal with (it might be an indexed view or a table)
-- the schema might or might not be specified
-- when not specified it is DBO
--===================================================================================
DECLARE @TableName SYSNAME
SELECT @TableName = 'Facts.FactBackOrder'
--===================================================================================
--===================================================================================
DECLARE @Schema SYSNAME
DECLARE @I INT
DECLARE @Z INT
SELECT @TableName = LTRIM(RTRIM(@TableName))
SELECT @Z = LEN(@TableName)
IF (@Z = 0) BEGIN
RAISERROR('Invalid @Tablename passed.',16,1)
END
SELECT @I = CHARINDEX('.',@TableName )
--SELECT @TableName ,@I
IF @I > 0 BEGIN
--===================================================================================
-- a schema and table name have been passed
-- example Facts.FactBackOrder
-- @Schema = Fact
-- @TableName = FactBackOrder
--===================================================================================
SELECT @Schema = SUBSTRING(@TABLENAME,1,@I-1)
SELECT @TableName = SUBSTRING(@TABLENAME,@I+1,@Z-@I)
END
ELSE BEGIN
--===================================================================================
-- just a table name have been passed
-- so the schema will be dbo
-- example Orders
-- @Schema = dbo
-- @TableName = Orders
--===================================================================================
SELECT @Schema = 'DBO'
END
--===================================================================================
-- Check whether the @SchemaName is valid in the current database
--===================================================================================
IF NOT EXISTS ( SELECT * FROM INFORMATION_SCHEMA.SCHEMATA K WHERE K.[SCHEMA_NAME] = @Schema ) BEGIN
RAISERROR('Invalid Schema Name.',16,1)
END
--SELECT @Schema as [@Schema]
-- ,@TableName as [@TableName]
DECLARE @R1 TABLE (
THE_NAME SYSNAME
,THE_SCHEMA SYSNAME
,THE_TABLE SYSNAME
,OBJECT_ID INT
,THE_TYPE SYSNAME
,PRIMARY KEY CLUSTERED (THE_SCHEMA,THE_NAME)
)
;WITH RADHE_01 AS (
SELECT QUOTENAME(SCHEMA_NAME(O.schema_id)) + '.' + QUOTENAME(O.NAME) AS [the_name]
,the_schema=SCHEMA_NAME(O.schema_id)
,the_table=O.NAME
,object_id =o.object_id
,[the_type]= CASE WHEN O.TYPE = 'U' THEN 'Table' ELSE 'View' END
from sys.objects O
where O.is_ms_shipped = 0
AND O.TYPE IN ('U','V')
)
INSERT INTO @R1 (
THE_NAME
,THE_SCHEMA
,THE_TABLE
,OBJECT_ID
,THE_TYPE
)
SELECT the_name
,the_schema
,the_table
,object_id
,the_type
FROM RADHE_01
WHERE the_schema = @Schema
AND the_table = @TableName
IF (@@ROWCOUNT = 0) BEGIN
RAISERROR('Invalid Table Name.',16,1)
END
ELSE BEGIN
SELECT THE_NAME
,THE_SCHEMA
,THE_TABLE
,OBJECT_ID
,THE_TYPE
FROM @R1
END
在不同的数据库中查找表:
if exists (select * from MyOtherDatabase.sys.tables where name = 'MyTable')
print 'Exists'
IF EXISTS
(
SELECT *
FROM sys.objects
WHERE object_id = OBJECT_ID(N'[dbo].[Mapping_APCToFANavigator]')
AND
type in (N'U')
)
BEGIN
-- Do whatever you need to here.
END
在上面的代码中，表名是mapping_apctofannavigator。
-- -- 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);
只是想提到一种情况，在这种情况下使用OBJECT_ID方法可能会更容易一些。INFORMATION_SCHEMA视图是每个数据库-下的对象
信息模式视图定义在一个名为 INFORMATION_SCHEMA。这个模式包含在每个数据库中。
https://msdn.microsoft.com/en-us/library/ms186778.aspx
因此，您访问的所有表都使用
IF EXISTS (SELECT 1
FROM [database].INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE='BASE TABLE'
AND TABLE_NAME='mytablename')
SELECT 1 AS res ELSE SELECT 0 AS res;
将只反映什么是在[数据库]。如果您想检查另一个数据库中是否存在表，而不需要每次都动态更改[database]， OBJECT_ID将允许您开箱操作。除
IF OBJECT_ID (N'db1.schema.table1', N'U') IS NOT NULL
SELECT 1 AS res ELSE SELECT 0 AS res;
效果和
IF OBJECT_ID (N'db2.schema.table1', N'U') IS NOT NULL
SELECT 1 AS res ELSE SELECT 0 AS res;
SQL SERVER 2016编辑:
从2016年开始，微软通过添加if exists关键字来删除语句，简化了在删除之前检查不存在对象的功能。例如,
drop table if exists mytablename
将在一行代码中完成与OBJECT_ID / INFORMATION_SCHEMA包装器相同的事情。
https://blogs.msdn.microsoft.com/sqlserverstorageengine/2015/11/03/drop-if-exists-new-thing-in-sql-server-2016/
