把指定表中的列添加到目标表中不包含的列

CREATE PROC pro_addColumn
(
@oldDB VARCHAR(20),
@newDB VARCHAR(20),
@oldtable VARCHAR(50),
@newtable VARCHAR(50)
)
AS
EXEC ('USE  '+ @newDB+'')
IF object_id(''+@newtable+'') is null 
 BEGIN
  PRINT @newtable+'不存在，创建表'
  EXEC('SELECT * INTO '+@newtable+' FROM '+@oldtable+' WHERE 1=2')
  PRINT '创建成功'
 END
ELSE 
BEGIN 
DECLARE @colname VARCHAR(30)
DECLARE @datatype VARCHAR(20)
DECLARE @length VARCHAR(20)
EXEC ('USE  '+ @oldDB+'')
DECLARE test_cursor CURSOR SCROLL FOR
select name ,type_name(xtype) AS datetype,length
from syscolumns where id=object_id(''+@oldtable+'')
OPEN test_cursor

FETCH NEXT FROM test_cursor INTO @colname,@datatype,@length
PRINT 'old:'+@colname+' '+@datatype+'  '+@length
WHILE @@FETCH_STATUS=0
BEGIN
EXEC ('USE  '+ @newDB+'')
IF NOT EXISTS(select name  
from syscolumns where id=object_id(''+@newtable+'')AND name=@colname)
BEGIN
PRINT '新表不存在列:'+@colname
IF @datatype='int' OR @datatype='bit' OR @datatype='text' OR @datatype='xml'
 BEGIN
 PRINT '为表'+@newtable+'添加列：'+@colname+'  '+@datatype+'  '+@length
   EXEC(' ALTER TABLE '+@newtable+' ADD '+@colname+'  '+@datatype+'')
 END
ELSE
 IF @length='-1'
  BEGIN
   SET @length='MAX'
  END
  PRINT '为表'+@newtable+'添加列：'+@colname+'  '+@datatype+'  '+@length
  EXEC(' ALTER TABLE  '+@newtable+' ADD '+@colname+'  '+@datatype+' ('+@length+')')
  END
ELSE
BEGIN
PRINT '新表中存在列：'+@colname
END

FETCH NEXT FROM test_cursor INTO @colname,@datatype,@length
END

CLOSE test_cursor
DEALLOCATE test_cursor
END