SQL面試題 (一)
有一個張員工工資表(SALARY),表有三列：員工編號(ID),工資(SALARY)
1.查詢id重複記錄
2.刪除id重複記錄，只保留第一條(說明，不需要考慮表中存在完全相同紀錄的情況)
SQL語句如下：
CREATE TABLE SALARY(
ID INT NOT NULL,
SALARY MONEY NOT NULL
)
INSERT INTO SALARY
SELECT 1,1000
UNION ALL SELECT 1,800
UNION ALL SELECT 2,1200
UNION ALL SELECT 3,1100
UNION ALL SELECT 3,1200
UNION ALL SELECT 3,1300
SELECT * FROM SALARY
-- 1
SELECT *
FROM SALARY
WHERE ID IN
(
SELECT ID
FROM SALARY
GROUP BY ID
HAVING COUNT(*)>1
)
-- 2
DELETE T
FROM SALARY T
WHERE EXISTS(SELECT 1 FROM SALARY WHERE T.ID=ID AND SALARY>T.SALARY)
SQL面試題 （二）
有一張工資表，包含三列：員工編號(ID),部門編號(GROUPS)，工資(SALARY)
1. .找到每個部門工資最高的人(包括並列第一)
2. 找到每個部門工資最高的人(只選一個)
SQL語句如下：
DECLARE @G TABLE(ID INT,GROUPS NVARCHAR(20),SALARY MONEY)
INSERT INTO @G
SELECT 1,1,1000
UNION ALL SELECT 2,1,1000
UNION ALL SELECT 3,1,800
UNION ALL SELECT 4,2,2000
-- 1
SELECT *
FROM @G G
WHERE NOT EXISTS(SELECT 1 FROM @G WHERE GROUPS=G.GROUPS AND SALARY>G.SALARY)
SELECT G.*
FROM @G G
INNER JOIN
(
SELECT GROUPS,MAX(SALARY) AS SALARY
FROM @G
GROUP BY GROUPS
)T
ON G.GROUPS=T.GROUPS
AND G.SALARY=T.SALARY
-- 2
SELECT MIN(G.ID),G.GROUPS,G.SALARY
FROM @G G
INNER JOIN
(
SELECT GROUPS,MAX(SALARY) AS SALARY
FROM @G
GROUP BY GROUPS
)T
ON G.GROUPS=T.GROUPS
AND G.SALARY=T.SALARY
GROUP BY G.GROUPS,G.SALARY
一定有更好的方法，請不吝賜教。