存儲過程中常使用的邏輯控制語句
--先申明個變量 。
DECLARE @Num INT;
SET @Num=0;
1. IF 語句
IF(@Num=0)
BEGIN
PRINT('Num value is '+CAST(@Num AS VARCHAR(4)));
END
2. WHILE 語句(當......的時候,執行循環體)
WHILE(@Num<>0)
BEGIN
PRINT('Num value is '+CAST(@Num AS VARCHAR(4)));
END
3. CASE 語句(特殊)
--創建測試臨時表
IF(OBJECT_ID('tempdb..#Books') IS NOT NULL)
BEGIN
DROP TABLE #Books;
END
CREATE TABLE #Books
(
BookName NVARCHAR(20),
BookCode NVARCHAR(20)
)
INSERT INTO #Books( BookName, BookCode ) VALUES(N'C# 本質論','JC556874');
INSERT INTO #Books( BookName, BookCode ) VALUES(N'JS 本質論','JS556874');
--簡單 Case 函數
SELECT
(
CASE BookCode
WHEN 'JC556874' THEN 'C#'
WHEN 'JS556874' THEN 'JS'
END
) CustFiled
FROM #Books
--搜索 Case 函數
SELECT
(
CASE
WHEN BookCode LIKE '%C%' THEN 'C#'
WHEN BookCode LIKE '%S%' THEN 'JS'
END
) CustFiled
FROM #Books
CASE 語句還可以放在 WHERE,GROUP 等中

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