删除表中字段的sql语句有哪些？

declare @name varchar(50)

select  @name =b.name from sysobjects b join syscolumns a on b.id = a.cdefault

where a.id = object_id('TableName')

and a.name ='ColumName'

exec('alter table TableName drop constraint ' + @name)

exec('alter table T_tableName drop constraint  报错信息的约束名' )

alter table dbo.T_tableName alter column Id BIGINT not NULL

alter table dbo.T_tableName add constraint PK_Id primary key(Id)