你与写的一手好sql的大佬可能就差这一道题!
1:建表语句
1.1:课程表
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `c`
-- ----------------------------
DROP TABLE IF EXISTS `c`;
CREATE TABLE `c` (
`CNO` int(11) NOT NULL DEFAULT '0' COMMENT '课程号',
`CNAME` varchar(11) DEFAULT NULL COMMENT '课程名称',
`CTEACHER` varchar(11) DEFAULT NULL COMMENT '课程老师名称',
PRIMARY KEY (`CNO`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of c
-- ----------------------------
INSERT INTO `c` VALUES ('1', '科学', '科学老师');
INSERT INTO `c` VALUES ('2', '编程', '编程老师');
INSERT INTO `c` VALUES ('3', '美术', '何炅老师');
1.2:学生表
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `s`
-- ----------------------------
DROP TABLE IF EXISTS `s`;
CREATE TABLE `s` (
`SNO` int(11) NOT NULL DEFAULT '0' COMMENT '学号',
`SNAME` varchar(11) DEFAULT NULL,
`AGE` int(2) DEFAULT NULL,
`SEX` int(1) DEFAULT NULL COMMENT '0-女 1-男',
PRIMARY KEY (`SNO`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of s
-- ----------------------------
INSERT INTO `s` VALUES ('1', '张三', '1', '1');
INSERT INTO `s` VALUES ('2', '李四', '2', '1');
INSERT INTO `s` VALUES ('3', '小丽', '3', '0');
INSERT INTO `s` VALUES ('4', '小花', '4', '0');
INSERT INTO `s` VALUES ('5', '王二麻子', '5', '1');
1.3:学生和课程关系表
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `sc`
-- ----------------------------
DROP TABLE IF EXISTS `sc`;
CREATE TABLE `sc` (
`SNO` int(11) DEFAULT NULL COMMENT '学号',
`CNO` int(22) DEFAULT NULL COMMENT '课程号',
`SCGRADE` decimal(11,2) DEFAULT NULL COMMENT '成绩'
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of sc
-- ----------------------------
INSERT INTO `sc` VALUES ('1', '1', '70.00');
INSERT INTO `sc` VALUES ('1', '2', '56.00');
INSERT INTO `sc` VALUES ('1', '3', '90.00');
INSERT INTO `sc` VALUES ('2', '1', '2.00');
INSERT INTO `sc` VALUES ('2', '3', '70.00');
INSERT INTO `sc` VALUES ('3', '3', '60.00');
INSERT INTO `sc` VALUES ('4', '3', '90.00');
INSERT INTO `sc` VALUES ('2', '2', '56.00');
INSERT INTO `sc` VALUES ('3', '1', '45.00');
INSERT INTO `sc` VALUES ('3', '2', '12.00');
INSERT INTO `sc` VALUES ('4', '1', '22.00');
INSERT INTO `sc` VALUES ('4', '2', '55.00');
1.4:学生和课程关系拓展表
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `sc_c`
-- ----------------------------
DROP TABLE IF EXISTS `sc_c`;
CREATE TABLE `sc_c` (
`CNO` int(11) NOT NULL DEFAULT '0',
`CNAME` varchar(11) DEFAULT NULL,
`AVG_GRADE` decimal(11,4) DEFAULT NULL,
PRIMARY KEY (`CNO`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of sc_c
-- ----------------------------
2:题目
1:把SC表中每门课程的平均成绩插入到另外一个已经存在的表SC_C(CNO,CNAME,AVG_GRADE)中,其中AVG_GRADE表示每门课程的平均成绩
2:从SC表中把选择何炅老师的课程的女生的选课记录删除
3:查询选何炅老师的课程的女生且成绩在80分以上
4:找出没有选修过何炅老师的课程的所有学生的姓名(两种写法)
5:列出有两门以上(包含两门)不及格课程(成绩小于60分)的学生的姓名及其平均成绩(两种方式)
6:列举出即学过1(科学)又学过2(编程)的所有学生姓名(两种方式)
7:列出1(科学)成绩比2(编程)的学生成绩高的所有学生的学号和姓名
8:列出1(科学)成绩比2(编程)的学生成绩高的所有学号及其1号课(科学)和2号课(编程)的成绩
3:参考答案
-- 1:把SC表中每门课程的平均成绩插入到另外一个已经存在的表SC_C(CNO,CNAME,AVG_GRADE)中,其中AVG_GRADE表示每门课程的平均成绩
INSERT INTO SC_C (CNO, CNAME, AVG_GRADE) SELECT
SC.CNO,
C.CNAME,
AVG(SC.SCGRADE)
FROM
`SC`
INNER JOIN C ON C.CNO = SC.CNO
GROUP BY
SC.CNO;
-- 2:从SC表中把选择何炅老师的课程的女生的选课记录删除
DELETE
FROM
SC,
S,
C
WHERE
SC.SNO = S.SNO
AND SC.CNO = C.CNO
AND C.CTEACHER = '何炅老师'
-- 3:查询选何炅老师的课程的女生且成绩在80分以上
SELECT
S.*
FROM
S
INNER JOIN SC ON SC.SNO = S.SNO
INNER JOIN C ON C.CNO = SC.CNO
WHERE
C.CTEACHER = '何炅老师'
AND SC.SCGRADE > 80
AND S.SEX = 0
-- 4:找出没有选修过何炅老师的课程的所有学生的姓名(两种写法)
SELECT
S.SNAME
FROM
S
WHERE
S.SNO NOT IN (
SELECT
S.SNO
FROM
S
INNER JOIN SC ON SC.SNO = S.SNO
INNER JOIN C ON C.CNO = SC.CNO
WHERE
C.CTEACHER = '何炅老师'
)
SELECT
SNAME
FROM
S
WHERE
NOT EXISTS (
SELECT
*
FROM
SC,
C
WHERE
SC.CNO = SC.CNO
AND SC.SNO = S.SNO
AND C.CTEACHER = '何炅老师'
)
-- 5:列出有两门以上(包含两门)不及格课程(成绩小于60分)的学生的姓名及其平均成绩(两种方式)
SELECT
S.SNAME,
AVG(sc.SCGRADE)
FROM
SC
INNER JOIN S ON S.SNO = sc.SNO
WHERE
sc.SNO IN (
SELECT
sc.SNO
FROM
SC
WHERE
SC.SCGRADE < 60
GROUP BY
sc.SNO
HAVING
COUNT(1)>= 2
)
GROUP BY
sc.SNO;
SELECT
S.SNAME,
AVG(sc.SCGRADE)
FROM
s,
sc,
(
SELECT
sc.SNO
FROM
SC
WHERE
SC.SCGRADE < 60
GROUP BY
sc.SNO
HAVING
COUNT(1) >= 2
) A
WHERE
A.SNO = s.SNO
AND s.SNO = sc.SNO
GROUP BY
sc.SNO
-- 6:列举出即学过1(科学)又学过2(编程)的所有学生姓名(两种方式)
SELECT
s.SNAME
FROM
s,
sc
WHERE
s.sno = sc.SNO
AND sc.CNO = 2
AND sc.SNO IN (
SELECT
sc.SNO
FROM
sc
WHERE
sc.CNO = 1
)
SELECT
s.SNAME
FROM
s,
(
SELECT
SNO
FROM
sc
WHERE
CNO IN (1, 2)
GROUP BY
SNO
HAVING
count(CNO) >= 2
) AS a
WHERE
s.sno = a.SNO
-- 7:列出1(科学)成绩比2(编程)的学生成绩高的所有学生的学号和姓名
SELECT
s.sno,
s.SNAME
FROM
s,
(
SELECT
sc.SNO,
sc.SCGRADE
FROM
sc
WHERE
sc.CNO = 1
) k,
(
SELECT
sc.SNO,
sc.SCGRADE
FROM
sc
WHERE
sc.CNO = 2
) b
WHERE
s.SNO = k.SNO
AND k.SNO = b.SNO
AND k.SCGRADE > b.SCGRADE
-- 8:列出1(科学)成绩比2(编程)的学生成绩高的所有学号及其1号课(科学)和2号课(编程)的成绩
SELECT
s.sno,
s.SNAME,
k.SCGRADE AS "1",
b.SCGRADE AS "2"
FROM
s,
(
SELECT
sc.SNO,
sc.SCGRADE
FROM
sc
WHERE
sc.CNO = 1
) k,
(
SELECT
sc.SNO,
sc.SCGRADE
FROM
sc
WHERE
sc.CNO = 2
) b
WHERE
s.SNO = k.SNO
AND k.SNO = b.SNO
AND k.SCGRADE > b.SCGRADE
