sql游标循环结果集

我们知道游标是一种对结果集操作的神器，使用游标，可以很方便的循环结果集，并对结果集进行数据处理。

1、建表

 CREATE TABLE [dbo].[Student](
     [Uid] [INT] IDENTITY(1,1) NOT NULL,
     [Name] [NCHAR](10) NULL,
     [BirthDay] [DATETIME] NULL,
     [Sex] [INT] NULL,
     [Age] [INT] NULL,
     [demo] [INT] NULL,
  CONSTRAINT [PK_Student] PRIMARY KEY CLUSTERED
 (
     [Uid] ASC
 )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
 ) ON [PRIMARY]

2、sql代码实例：

 BEGIN
     DECLARE @a INT ,
         @error INT;
     DECLARE @temp VARCHAR(50);
     SET @a = 2;
     SET @error = 0;

    --定义一个游标
     DECLARE order_cursor CURSOR
    --申明游标为Uid
     FOR
         ( SELECT    [Uid]
           FROM      Student
         );
     --打开游标--
     OPEN order_cursor;
     --开始循环游标变量--
     FETCH NEXT FROM order_cursor INTO @temp;
     WHILE @@FETCH_STATUS = 0    --返回被 FETCH语句执行的最后游标的状态--
         BEGIN
             UPDATE  Student
             SET     Age = 15 + @a ,
                     demo = @a
             WHERE   Uid = @temp;
             SET @a = @a + 1;
             SET @error = @error + @@ERROR;   --记录每次运行sql后是否正确，0正确
             FETCH NEXT FROM order_cursor INTO @temp;   --转到下一个游标，没有会死循环
         END;
     CLOSE order_cursor;  --关闭游标
     DEALLOCATE order_cursor;   --释放游标
 END;
 GO
 

查看表

 SELECT  * FROM    Student;

结果如下

3、实例2

下面是循环插入数据的SQL实例。

 declare @orderN varchar(50)--临时变量，用来保存游标值
 declare y_curr cursor FOR --申明游标 为orderNum

 SELECT  FContractNo
 FROM    dbo.v_ContractInfo
 WHERE   FDate >= '2019-04-01 00:00:000'
         AND PayMode = 1
         AND Fstatus = 1
         AND FranchiseeNo IN ( '', '', '', '', '', '', '' )
         AND (WbStatus IS NULL OR WbStatus=0 ) AND FContractNo NOT IN (SELECT OrderNO FROM CF_BookingCheck )
 open y_curr --打开游标
 fetch next from Y_curr into @orderN ----开始循环游标变量
 while(@@fetch_status=0)---返回被 FETCH  语句执行的最后游标的状态，而不是任何当前被连接打开的游标的状态。

 BEGIN
 PRINT(@orderN)
 INSERT INTO CF_BookingCheck (OrderNO,OverDays,WbStatus,FinanceType,WbChecker,WbCheckDate)VALUES (@orderN,0,3,0,'系统','2019-04-30 00:00:000')
 fetch next from y_curr into @orderN --开始循环游标变量
 END
 close y_curr--关闭游标
 deallocate y_curr --释放游标