sql单表查询练习题
1. 查看course表结构的SQL命令是什么？
A. SELECT * FROM exam.course;
B. \d exam.course;
C. \d+ exam.course;
D. DESCRIBE exam.course;
答案：C
2. 使用哪个SQL命令可以查看exam.course表中的所有数据？
A. SELECT * FROM exam.subject;
B. SELECT * FROM exam.course;
C. SHOW TABLES FROM exam.course;
D. DESCRIBE exam.course;
答案：B
3. 在SQL中，如何为字段别名添加双引号？
A. SELECT 1+1 AS '1+1=?' FROM dual;
B. SELECT 1+1 AS "1+1=?" FROM dual;
C. SELECT "1+1=?" FROM dual;
D. SELECT '1+1=?' FROM dual;
答案：B
4. SQL中，哪个命令用于选择所有列？
A. SELECT *
B. SELECT ALL
C. SELECT ALL COLUMNS
D. SELECT EVERY COLUMN
答案：A
5. SQL中字符串拼接运算符是什么？
A. +
B. ||
C. CONCAT()
D. JOIN()
答案：B
6. SQL中，哪个函数用于获取当前日期？
A. NOW()
B. CURRENT_DATE()
C. GETDATE()
D. DATE()
答案：B
7. SQL中，哪个关键字用于条件表达式？
A. IF
B. CASE
C. SWITCH
D. WHEN
答案：B
8. 在SQL中，哪个操作符用于数值型字段条件匹配？
A. =
B. >
C. <
D. LIKE
答案：ABC
9. SQL中，哪个关键字用于字符型字段条件匹配（等值匹配）？
A. IN
B. LIKE
C. =
D. MATCH
答案：C
10. SQL中，哪个关键字用于字符型字段条件匹配（列表匹配）？
A. IN
B. LIKE
C. =
D. MATCH
答案：A
11. SQL中，哪个关键字用于按注册日期升序排列？
A. ORDER BY reg_date DESC
B. ORDER BY reg_date ASC
C. SORT BY reg_date
D. RANK BY reg_date
答案：B
12. SQL中，哪个关键字用于多列组合排序？
A. ORDER BY city, reg_date DESC
B. SORT BY city, reg_date DESC
C. RANK BY city, reg_date DESC
D. GROUP BY city, reg_date DESC
答案：A
13. SQL中，哪个选项用于将NULL值始终放在排序的最前面？
A. NULLS LAST
B. NULLS FIRST
C. NULLS ASC
D. NULLS DESC
答案：B
14. SQL中，哪个子句用于限制查询结果的数量？
A. LIMIT
B. TOP
C. FETCH
D. SELECT
答案：A
15. SQL中，哪个函数用于计算去重后的城市数量？
A. COUNT(ALL city)
B. COUNT (DISTINCT city)
C. COUNT(city)
D. SUM(DISTINCT city)
答案：B
16. SQL中，如何表示字符串的拼接？
A. CONCAT('Hello', 'World')
B. 'Hello' + 'World'
C. 'Hello' || 'World'
D. 'Hello' & 'World'
答案：C
17. SQL中，如何表示选择当前日期加上7天的结果？
A. SELECT CURRENT_DATE + 7
B. SELECT GETDATE() + 7
C. SELECT CURRENT_DATE + INTERVAL '7 days'
D. SELECT current date()+7 As nextweek
答案：D
18. SQL中，如何使用CASE WHEN表达式来输出成绩等级？
A. CASE WHEN score >= 90 THEN 'High' END
B. CASE WHEN score >= 90 THEN 'High' WHEN score >= 70 THEN 'Medium' ELSE 'Low' END
C. IF score >= 90 THEN 'High' ELSE 'Low' END
D. SWITCH score >= 90 THEN 'High' END
答案：B
19. SQL中，如何查询分数大于80的学员信息？
A. SELECT * FROM exam.score WHERE score > 80
B. SELECT * FROM exam.score WHERE score >= 80
C. SELECT * FROM exam.score WHERE score = 80
D. SELECT * FROM exam.score WHERE score < 80
答案：A
20. SQL中，如何查询城市为Beijing的学员信息？
A. SELECT * FROM exam.student WHERE city = 'Beijing'
B. SELECT * FROM exam.student WHERE city LIKE 'Beijing'
C. SELECT * FROM exam.student WHERE city IN ('Beijing')
D. SELECT * FROM exam.student WHERE city != 'Beijing'
答案：A
21. SQL中，如何查询城市为Beijing或者Chongqing的学员信息？
A. SELECT * FROM exam.student WHERE city IN ('Beijing', 'Chongqing')
B. SELECT * FROM exam.student WHERE city = 'Beijing' OR city = 'Chongqing'
C. SELECT * FROM exam.student WHERE city LIKE 'Beijing' OR city LIKE 'Chongqing'
D. SELECT * FROM exam.student WHERE city = 'Beijing' AND city = 'Chongqing'
答案：A
22. SQL中，如何证明AND优先级高于OR？
A. SELECT 1 FROM dual WHERE 1=1 OR 1=0 AND 1=0
B. SELECT 1 FROM dual WHERE 1=1 AND 1=0 OR 1=1
C. SELECT 1 FROM dual WHERE 1=1 OR (1=0 AND 1=1)
答案：BC
23. SQL中，使用括号改变了AND的优先级？
A. SELECT 1 FROM dual WHERE 0=9 AND(0=1 OR 1=1)
B. SELECT 1 FROM dual WHERE 0=9 OR(0=1 AND 1=1)
C. SELECT 1 FROM dual WHERE 0=9 AND 0=1 OR 1=1
D. SELECT 1 FROM dual WHERE (0=9 AND 0=1) OR 1=1
答案：B
24. SQL中，如何查询姓名以'S'字符打头的学员信息？
A. SELECT * FROM exam.student WHERE sname LIKE 'S%'
B. SELECT * FROM exam.student WHERE sname LIKE '%S'
C. SELECT * FROM exam.student WHERE sname LIKE '_S'
D. SELECT * FROM exam.student WHERE sname LIKE 's%'
答案：A
25. SQL中，如何查询姓名以'g'字符结尾的学员信息？
A. SELECT * FROM exam.student WHERE sname LIKE '%g'
B. SELECT * FROM exam.student WHERE sname LIKE 'g%'
C. SELECT * FROM exam.student WHERE sname LIKE '_g'
D. SELECT * FROM exam.student WHERE sname LIKE 'G%'
答案：A