我正在使用SQL Server,正在尝试删除一列。 表模式如下:
CREATE TABLE [dbo].[XYZ](
[ID] [int] NOT NULL,
[DSC] [varchar](255) NULL,
[LOWER_LIMIT] [int] NOT NULL,
[UPPER_LIMIT] [int] NOT NULL,
CONSTRAINT [XP_XYZ] PRIMARY KEY CLUSTERED
(
[ID] ASC
) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO
当我尝试删除列时:
ALTER TABLE [SENSOR]
DROP COLUMN LOWER_LIMIT;
我被要求在之前取消约束
The object 'DF__SENSOR__LOWER_LI__08B54D69' is dependent on column 'LOWER_LIMIT'.
Msg 4922, Level 16, State 9, Line 45
ALTER TABLE DROP COLUMN LOWER_LIMIT failed because one or more objects access this column.
现在,我正在编写用于删除列的flyway脚本,直到运行更高级别的环境中约束更改时,我才尝试运行drop命令,才知道约束。我如何起草飞行路线以删除此专栏?
答案 0 :(得分:0)
最后,在Stackoverflow的帮助下,我能够执行以下操作:
IF EXISTS(SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = N'SENSOR'
AND COLUMN_NAME = N'LOWER_LIMIT')
BEGIN
DECLARE @sql NVARCHAR(MAX)
WHILE 1=1
BEGIN
SELECT TOP 1 @sql = N'alter table [SENSOR] drop constraint ['+dc.name+N']'
FROM sys.default_constraints dc
JOIN sys.columns c
ON c.default_object_id = dc.object_id
WHERE dc.parent_object_id = OBJECT_ID('[SENSOR]') AND c.name = N'LOWER_LIMIT'
IF @@ROWCOUNT = 0
BEGIN
PRINT 'DELETED Constraint on column LOWER_LIMIT'
BREAK
END
EXEC (@sql)
END;
ALTER TABLE [SENSOR] DROP COLUMN LOWER_LIMIT;
PRINT 'DELETED column LOWER_LIMIT'
END
ELSE
PRINT 'Column LOWER_LIMIT does not exist'
GO
原始帖子为here