游标的使用实例(Sqlserver版本)

declare mycur cursor for    ---申明游标mycur
select name from t_stu

open mycur    ---打开游标
---操作内容
close mycur    ---关闭游标

deallocate mycur   ---释放资源

create function [dbo].[getCols]
( @table_name AS varchar(50) 
)
RETURNS varchar(2000)
AS
BEGIN
  DECLARE @colname VARCHAR(50)
  DECLARE @typename VARCHAR(50)
  DECLARE @result varchar(2000)  
  set @result = ‘‘
  DECLARE mycur CURSOR FOR     ---定义游标
    select c.name as columnname,ty.name as typename
        from sys.columns c 
        inner join sys.tables t on t.object_id=c.object_id
        inner join sys.types ty on ty.system_type_id=c.system_type_id
        where t.name = @table_name and ty.name !=‘sysname‘        ---传入参数@table_name
        order by t.name,c.column_id

    OPEN mycur       ---打开游标
    FETCH NEXT FROM mycur into        ----获取下一条数据
    @colname,@typename                ----将获取的数据保存到变量中
    
    WHILE @@FETCH_STATUS = 0         ----返回上次执行Fetch命令的状态，0：成功 -1：失败 -2：被提取的行不存在
        BEGIN
            if @result = null or @result = ‘‘
            begin
               SET @result = @colname
            end
            else
            begin
               SET @result = @result + ‘,‘ + @colname    
            end
        FETCH NEXT FROM mycur into    ---获取下一条数据
              @colname,@typename 
        END
    CLOSE mycur       ---关闭游标
        DEALLOCATE mycur   ----释放资源
  RETURN @result
END