♥ 前 言
2021到了最后一個月份，年后肯定有蠻多小伙伴需要跳槽換工作，但對於年限稍短的軟件測試工程師，難免會需要進行筆試，而在筆試中，基本都會碰到一道關於數據庫的大題，今天這篇文章呢，就收錄了下最近學員反饋上來的一些數據庫筆試真題，包含答案！
1、依據以下學生表、班級表，按要求寫 SQL
答案：
1、
select * from student a
left join class b on a.c_id = b.id
where score = (
select max(score) from student)
2、
select b.name,count(*),avg(score) as avgScore from student a,class b
where a.c_id = b.id
group by b.name
order by avgScore;
2、Table A 保存客戶的基本信息；Table B 保存客戶的資產負債信息。按要求寫 SQL
答案：
（1）select ID from A where name = '李四';
（2）select NO,NAME，ID from A,B where A.NO = B.NO AND DEPOSIT >= 1000;
（3）select COUNTRY,count(*) FROM A GROUP BY COUNTRY;
（4）SELECT '80 后' as 年齡段，sum(CREDIT) AS '信用卡余額' FROM A,B WHERE A.NO = B.NO AND BIRTH >= 19800101 AND BIRTH < 19900101
UNION
SELECT '90 后' as 年齡段，sum(CREDIT) AS '信用卡余額' FROM A,B WHERE A.NO = B.NO AND BIRTH >= 19900101 AND BIRTH < 20000101;
3、數據庫(編寫示例 sql)
答案：
-
select orderNo, if(status=1,'新建','處理中') from OrderTrans;
-
select DATE_FORMAT(a.crttime,'%m-%d-%Y') ,username,count(*) from testCase a,User b where a.crtUser = b.UserId group by DATE_FORMAT(a.crttime,'%m-%d-%Y'),b.username, having status = '成功';
-
select count(*),sum(amount),DATE_FORMAT(crttime,'%m-%d-%Y') from OrderInfo group by
DATE_FORMAT(crttime,'%m-%d-%Y')；
4、現有三張數據表如下：學生資料表：記錄學生基本信息；課程表：記錄課程基本信息；成績表：記錄每人各門課程成績的信息，1 個學生對應多個成績，1 個成績只屬於一個學生，一個課程
答案：
-
Select * from students where jg = ‘湖北’ and birthday = ‘1992-6-1’ order by no asc;
-
Select avg(so.cj),min(so.cj),max(so.cj),sum(so.cj) from student st,course c,source so where st.no = so.no and c.kebh=so.kebh and st.name = ‘王華’ group by st.no;
-
Select st.no,st.name,st.bj,c.kebh,c.kcmc,so.cj from student st,course c,source so where st.no = so.no and c.kebh=so.kebh and st.name = ‘張三’ order by so.cj desc;
答案：
-
Select Consultant.SubsidiaryID, BaseOrder.* from Consultant, BaseOrder where Consultant.ConsultantID = BaseOrder.ConsultantID and Consultant.SubsidiaryID = 29 order by Orderid desc;
-
Select BaseOrder.ConsultantID,sum(OrderDetails.TotalPrice) from BaseOrder,OrderDetails where BaseOrder.Orderid=OrderDetails.Orderid and month(OrderDate) = 5 group by BaseOrder.ConsultantID;
-
Insert into Consultant (ConsultantID,ConstultantStatusID,SubsidiaryID,Name) values (200000,10,29,’Gary’);
-
Delete from Consultant where Name like ‘%Gary%’;
-
Update BaseOrder set OrderDate = sysdate() where ConsultantID in (select ConsultantID from BaseOrder where ConsultantID=100003 order by OrderDate desc limit 0,1);
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