SQL存储过程+游标 循环批量()操作数据

本人收集的，挺有用的

1. 利用游标循环更新、删除MemberAccount表中的数据

DECLARE My_Cursor CURSOR --定义游标
FOR (SELECT * FROM dbo.MemberAccount) --查出需要的集合放到游标中
OPEN My_Cursor; --打开游标
FETCH NEXT FROM My_Cursor ; --读取第一行数据
WHILE @@FETCH_STATUS = 0
    BEGIN
        --UPDATE dbo.MemberAccount SET UserName = UserName + 'A' WHERE CURRENT OF My_Cursor; --更新
        --DELETE FROM dbo.MemberAccount WHERE CURRENT OF My_Cursor; --删除
        FETCH NEXT FROM My_Cursor; --读取下一行数据
    END
CLOSE My_Cursor; --关闭游标
DEALLOCATE My_Cursor; --释放游标
GO

2.利用游标循环更新MemberService表中的数据（更新每个用户所购买服务的时间）

DECLARE @UserId varchar(50)
DECLARE My_Cursor CURSOR --定义游标
FOR (SELECT UserId FROM dbo.MemberAccount) --查出需要的集合放到游标中
OPEN My_Cursor; --打开游标
FETCH NEXT FROM My_Cursor INTO @UserId; --读取第一行数据(将MemberAccount表中的UserId放到@UserId变量中)
WHILE @@FETCH_STATUS = 0
    BEGIN
        PRINT @UserId; --打印数据(打印MemberAccount表中的UserId)
        UPDATE dbo.MemberService SET ServiceTime = DATEADD(Month, 6, getdate()) WHERE UserId = @UserId; --更新数据
        FETCH NEXT FROM My_Cursor INTO @UserId; --读取下一行数据(将MemberAccount表中的UserId放到@UserId变量中)
    END
CLOSE My_Cursor; --关闭游标
DEALLOCATE My_Cursor; --释放游标
GO

 sql 存储过程里面如何 对数据集循环

A. 在简单的游标中使用 FETCH

以下示例为 Person.Contact 表中姓氏以字母 B 开头的行声明了一个简单的游标，并使用 FETCH NEXT 逐个提取这些行。FETCH 语句以单行结果集形式返回在 DECLARE CURSOR 中指定的列的值。

USE AdventureWorks
GO
DECLARE contact_cursor CURSOR FOR
SELECT LastName FROM Person.Contact
WHERE LastName LIKE 'B%'
ORDER BY LastName
 
OPEN contact_cursor
 
-- Perform the first fetch.
FETCH NEXT FROM contact_cursor
 
-- Check @@FETCH_STATUS to see if there are any more rows to fetch.
WHILE @@FETCH_STATUS = 0
BEGIN
   -- This is executed as long as the previous fetch succeeds.
   FETCH NEXT FROM contact_cursor
END
 
CLOSE contact_cursor
DEALLOCATE contact_cursor
GO

B. 使用 FETCH 将值存入变量

以下示例与示例 A 相似，但 FETCH 语句的输出存储于局部变量而不是直接返回到客户端。PRINT 语句将变量组合成单一字符串并将其返回到客户端。

USE AdventureWorks
GO
-- Declare the variables to store the values returned by FETCH.
DECLARE @LastName varchar(50), @FirstName varchar(50)
 
DECLARE contact_cursor CURSOR FOR
SELECT LastName, FirstName FROM Person.Contact
WHERE LastName LIKE 'B%'
ORDER BY LastName, FirstName
 
OPEN contact_cursor
 
-- Perform the first fetch and store the values in variables.
-- Note: The variables are in the same order as the columns
-- in the SELECT statement. 
 
FETCH NEXT FROM contact_cursor
INTO @LastName, @FirstName
 
-- Check @@FETCH_STATUS to see if there are any more rows to fetch.
WHILE @@FETCH_STATUS = 0
BEGIN
 
   -- Concatenate and display the current values in the variables.
   PRINT 'Contact Name: ' + @FirstName + ' ' +  @LastName
 
   -- This is executed as long as the previous fetch succeeds.
   FETCH NEXT FROM contact_cursor
   INTO @LastName, @FirstName
END
 
CLOSE contact_cursor
DEALLOCATE contact_cursor
GO