SQL Server 遊標的使用示例
Ø 簡介
本文主要記錄 MSSQL 中的遊標使用示例，在有必要時方便借鑑查閱。遊標一般定義在某段功能性的 SQL 語句中，或者儲存過程中。之所以選擇用它，是因為有時候無法使用簡單的 SQL 語句滿足我們需求，比如需要對結果集中的每一條資料，根據不同條件進行不同操作（CRUD），這時我們就可以使用遊標來完成。
提示：來之 DBA 的傑作，哈哈~~
1. 示例1：
1) 本示例，用於初始化某新表的資料。使用遊標遍歷查詢結果集，根據遍歷的資料再插入另外兩張表。
2) 注意：在遊標開啟後，如果在未關閉之前發生了異常，遊標不能正常關閉，會導致該遊標一直存在。所以，我們可以將遊標定義在
IF(OBJECT_ID('SP_Init_CustomerNewOpening', 'P') IS NOT NULL)
DROP PROCEDURE SP_Init_CustomerNewOpening;
GO
CREATE PROCEDURE SP_Init_CustomerNewOpening
AS
INSERT INTO Sys_DbLog(LogTime, Type, Item, Message, Remark) VALUES
BEGIN TRY
BEGIN TRANSACTION;
DECLARE @RewardsMoney decimal(18,2) = CAST(ISNULL((SELECT Value FROM Config WHERE Id=79),
DECLARE @NewOpenMoney decimal(18,2) = 0;
DECLARE @CustNewOpenId int;
DECLARE @PayTime datetime, @Address nvarchar(500), @CustomerId bigint, @EmplCityId int, @EmployeeId int, @RealTotal decimal(18,2);
DECLARE cursor_CustomerNewOpening CURSOR GLOBAL SCROLL DYNAMIC SCROLL_LOCKS
FOR SELECT PayTime, Address, CustomerId, EmplCityId, EmployeeId, SUM(RealTotal) AS RealTotal FROM
(
SELECT T1.PayTime, T1.Address, T1.CustomerId, T1.EmplCityId, T1.EmployeeId, T2.RealTotal FROM
(
SELECT T2.PayTime, T2.Address, T1.Id AS CustomerId, T3.CityId AS EmplCityId, T3.EmployeeId FROM Customer AS T1
INNER JOIN Orders AS T2 ON(T1.BdBonus = T2.Id)
INNER JOIN Sys_EmployeeProfile AS T3 ON(T2.SalesUserId = T3.EmployeeId)
WHERE T1.BdBonus > 0
) AS T1
INNER JOIN Orders AS T2 ON(T1.PayTime = T2.PayTime AND T1.Address = T2.Address)
WHERE 1=1
) AS T WHERE 1=1
GROUP BY PayTime, Address, CustomerId, EmplCityId, EmployeeId;
OPEN cursor_CustomerNewOpening;
FETCH FIRST FROM cursor_CustomerNewOpening INTO @PayTime, @Address, @CustomerId, @EmplCityId, @EmployeeId, @RealTotal;
WHILE(@@FETCH_STATUS = 0)
BEGIN
--插入客戶新開
SET @NewOpenMoney = CASE WHEN @RealTotal > 999 THEN 999 WHEN @RealTotal > 699 THEN 699 ELSE @RealTotal END;
INSERT INTO Crm_CustomerNewOpening(CustomerId, EmplCityId, EmployeeId, RewardsMoney, NewOpenMoney, RealTotal,
RefundmentMoney, PayTime, NewOpenStatus, AuditorId, AuditorTime, AuditDesc, CreateTime, UpdateTime)
VALUES(@CustomerId, @EmplCityId, @EmployeeId, @RewardsMoney, @NewOpenMoney, @RealTotal,
0, @PayTime, 4/*歷史有效*/, NULL, NULL, NULL, GETDATE(), NULL);
SET @CustNewOpenId = SCOPE_IDENTITY();
--插入訂單新開
INSERT INTO Crm_OrderNewOpening(CustNewOpenId, OrderId, OrderNum, RealTotal, RefundmentMoney, CreateTime, UpdateTime)
SELECT 0, T1.Id, T1.OrderNum, T1.RealTotal, 0, GETDATE(), NULL FROM Orders AS T1
WHERE 1=1
AND T1.PayTime = @PayTime
AND T1.Address = @Address;
FETCH NEXT FROM cursor_CustomerNewOpening INTO @PayTime, @Address, @CustomerId, @EmplCityId, @EmployeeId, @RealTotal;
END
CLOSE cursor_CustomerNewOpening;
DEALLOCATE cursor_CustomerNewOpening;
COMMIT;
INSERT INTO Sys_DbLog(LogTime, Type, Item, Message, Remark) VALUES(GETDATE(), 'info', 'SP_Init_CustomerNewOpening', '儲存過程執行結束', NULL);
END TRY
BEGIN CATCH
ROLLBACK;
DECLARE @Message varchar(8000) = '錯誤：行號[' + CAST(ERROR_LINE() AS nvarchar(20)) + ']，' + ERROR_MESSAGE();
INSERT INTO Sys_DbLog(LogTime, Type, Item, Message, Remark) VALUES(GETDATE(), 'error', 'SP_Init_CustomerNewOpening', @Message, '事物已回滾');
END CATCH
GO
2. 示例2：
1) 本示例，建立了一個儲存過程，建立了兩個遊標。
2) 第一個遊標，使用遊標完成更新遍歷的記錄，再使用遍歷的資料完成對另外兩張表的 Insert 操作。
3) 第二個遊標，完成對3張表的更新操作，在示例中使用了當前遊標記錄作為更新條件，例如：WHERE CURRENT OF cursor_Crm_Refundment。
4) 該儲存過程用於定時任務執行，比在程式中去查詢資料，然後再遍歷寫入資料效率上還是比較有優勢的，而且便於維護。SQL 程式碼如下：
IF(OBJECT_ID('SP_Add_CustomerNewOpening', 'P') IS NOT NULL)
DROP PROCEDURE SP_Add_CustomerNewOpening;
GO
CREATE PROCEDURE SP_Add_CustomerNewOpening
(
@StartTime datetime, --開始時間
@EndTime datetime --結束時間
)
AS
INSERT INTO Sys_DbLog(LogTime, Type, Item, Message, Remark) VALUES(GETDATE(), 'info', 'SP_Add_CustomerNewOpening', '開始儲存過程執行開始', NULL);
DECLARE @RewardsMoney decimal(18,2) = CAST(ISNULL((SELECT Value FROM Config WHERE Id=79), '0') AS decimal(18,2));
DECLARE @NewOpenMoney decimal(18,2) = CAST(ISNULL((SELECT Value FROM Config WHERE Id=80), '0') AS decimal(18,2));
BEGIN TRY
BEGIN TRANSACTION;
--1. 新增新開客戶
DECLARE @OrderNewOpenId int, @CustNewOpenId int;
DECLARE @UserId bigint, @PayTime datetime, @Address nvarchar(500), @CustomerId bigint, @EmplCityId int, @EmployeeId int, @RealTotal decimal(18,2);
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