SQL测试题

一.网上收集了一些测试题，对于掌握SQL查询语句。

 /*
  Navicat MySQL Data Transfer

  Source Server         : lizebo's MYSQL
  Source Server Type    : MySQL
  Source Server Version : 50720
  Source Host           : localhost:3306
  Source Schema         : sql练习

  Target Server Type    : MySQL
  Target Server Version : 50720
  File Encoding         : 65001

  Date: 07/11/2017 20:09:05
 */

 SET NAMES utf8mb4;
 SET FOREIGN_KEY_CHECKS = 0;

 -- ----------------------------
 -- Table structure for class
 -- ----------------------------
 DROP TABLE IF EXISTS `class`;
 CREATE TABLE `class`  (
   `cid` int(11) NOT NULL AUTO_INCREMENT,
   `caption` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
   PRIMARY KEY (`cid`) USING BTREE
 ) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

 -- ----------------------------
 -- Records of class
 -- ----------------------------
 INSERT INTO `class` VALUES (1, '三年二班');
 INSERT INTO `class` VALUES (2, '三年三班');
 INSERT INTO `class` VALUES (3, '一年二班');
 INSERT INTO `class` VALUES (4, '二年九班');

 -- ----------------------------
 -- Table structure for course
 -- ----------------------------
 DROP TABLE IF EXISTS `course`;
 CREATE TABLE `course`  (
   `cid` int(11) NOT NULL AUTO_INCREMENT,
   `cname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
   `teacher_id` int(11) NOT NULL,
   PRIMARY KEY (`cid`) USING BTREE,
   INDEX `fk_course_teacher`(`teacher_id`) USING BTREE,
   CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`) ON DELETE RESTRICT ON UPDATE RESTRICT
 ) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

 -- ----------------------------
 -- Records of course
 -- ----------------------------
 INSERT INTO `course` VALUES (1, '生物', 1);
 INSERT INTO `course` VALUES (2, '物理', 2);
 INSERT INTO `course` VALUES (3, '体育', 3);
 INSERT INTO `course` VALUES (4, '美术', 2);

 -- ----------------------------
 -- Table structure for score
 -- ----------------------------
 DROP TABLE IF EXISTS `score`;
 CREATE TABLE `score`  (
   `sid` int(11) NOT NULL AUTO_INCREMENT,
   `student_id` int(11) NOT NULL,
   `course_id` int(11) NOT NULL,
   `num` int(11) NOT NULL,
   PRIMARY KEY (`sid`) USING BTREE,
   INDEX `fk_score_student`(`student_id`) USING BTREE,
   INDEX `fk_score_course`(`course_id`) USING BTREE,
   CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`) ON DELETE RESTRICT ON UPDATE RESTRICT,
   CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`) ON DELETE RESTRICT ON UPDATE RESTRICT
 ) ENGINE = InnoDB AUTO_INCREMENT = 53 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

 -- ----------------------------
 -- Records of score
 -- ----------------------------
 INSERT INTO `score` VALUES (1, 1, 1, 10);
 INSERT INTO `score` VALUES (2, 1, 2, 9);
 INSERT INTO `score` VALUES (5, 1, 4, 66);
 INSERT INTO `score` VALUES (6, 2, 1, 8);
 INSERT INTO `score` VALUES (8, 2, 3, 68);
 INSERT INTO `score` VALUES (9, 2, 4, 99);
 INSERT INTO `score` VALUES (10, 3, 1, 77);
 INSERT INTO `score` VALUES (11, 3, 2, 66);
 INSERT INTO `score` VALUES (12, 3, 3, 87);
 INSERT INTO `score` VALUES (13, 3, 4, 99);
 INSERT INTO `score` VALUES (14, 4, 1, 79);
 INSERT INTO `score` VALUES (15, 4, 2, 11);
 INSERT INTO `score` VALUES (16, 4, 3, 67);
 INSERT INTO `score` VALUES (17, 4, 4, 100);
 INSERT INTO `score` VALUES (18, 5, 1, 79);
 INSERT INTO `score` VALUES (19, 5, 2, 11);
 INSERT INTO `score` VALUES (20, 5, 3, 67);
 INSERT INTO `score` VALUES (21, 5, 4, 100);
 INSERT INTO `score` VALUES (22, 6, 1, 9);
 INSERT INTO `score` VALUES (23, 6, 2, 100);
 INSERT INTO `score` VALUES (24, 6, 3, 67);
 INSERT INTO `score` VALUES (25, 6, 4, 100);
 INSERT INTO `score` VALUES (26, 7, 1, 9);
 INSERT INTO `score` VALUES (27, 7, 2, 100);
 INSERT INTO `score` VALUES (28, 7, 3, 67);
 INSERT INTO `score` VALUES (29, 7, 4, 88);
 INSERT INTO `score` VALUES (30, 8, 1, 9);
 INSERT INTO `score` VALUES (31, 8, 2, 100);
 INSERT INTO `score` VALUES (32, 8, 3, 67);
 INSERT INTO `score` VALUES (33, 8, 4, 88);
 INSERT INTO `score` VALUES (34, 9, 1, 91);
 INSERT INTO `score` VALUES (35, 9, 2, 88);
 INSERT INTO `score` VALUES (36, 9, 3, 67);
 INSERT INTO `score` VALUES (37, 9, 4, 22);
 INSERT INTO `score` VALUES (38, 10, 1, 90);
 INSERT INTO `score` VALUES (39, 10, 2, 77);
 INSERT INTO `score` VALUES (40, 10, 3, 43);
 INSERT INTO `score` VALUES (41, 10, 4, 87);
 INSERT INTO `score` VALUES (42, 11, 1, 90);
 INSERT INTO `score` VALUES (43, 11, 2, 77);
 INSERT INTO `score` VALUES (44, 11, 3, 43);
 INSERT INTO `score` VALUES (45, 11, 4, 87);
 INSERT INTO `score` VALUES (46, 12, 1, 90);
 INSERT INTO `score` VALUES (47, 12, 2, 77);
 INSERT INTO `score` VALUES (48, 12, 3, 43);
 INSERT INTO `score` VALUES (49, 12, 4, 87);
 INSERT INTO `score` VALUES (52, 13, 3, 87);

 -- ----------------------------
 -- Table structure for student
 -- ----------------------------
 DROP TABLE IF EXISTS `student`;
 CREATE TABLE `student`  (
   `sid` int(11) NOT NULL AUTO_INCREMENT,
   `gender` char(1) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
   `class_id` int(11) NOT NULL,
   `sname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
   PRIMARY KEY (`sid`) USING BTREE,
   INDEX `fk_class`(`class_id`) USING BTREE,
   CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`) ON DELETE RESTRICT ON UPDATE RESTRICT
 ) ENGINE = InnoDB AUTO_INCREMENT = 17 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

 -- ----------------------------
 -- Records of student
 -- ----------------------------
 INSERT INTO `student` VALUES (1, '男', 1, '理解');
 INSERT INTO `student` VALUES (2, '女', 1, '钢蛋');
 INSERT INTO `student` VALUES (3, '男', 1, '张三');
 INSERT INTO `student` VALUES (4, '男', 1, '张一');
 INSERT INTO `student` VALUES (5, '女', 1, '张二');
 INSERT INTO `student` VALUES (6, '男', 1, '张四');
 INSERT INTO `student` VALUES (7, '女', 2, '铁锤');
 INSERT INTO `student` VALUES (8, '男', 2, '李三');
 INSERT INTO `student` VALUES (9, '男', 2, '李一');
 INSERT INTO `student` VALUES (10, '女', 2, '李二');
 INSERT INTO `student` VALUES (11, '男', 2, '李四');
 INSERT INTO `student` VALUES (12, '女', 3, '如花');
 INSERT INTO `student` VALUES (13, '男', 3, '刘三');
 INSERT INTO `student` VALUES (14, '男', 3, '刘一');
 INSERT INTO `student` VALUES (15, '女', 3, '刘二');
 INSERT INTO `student` VALUES (16, '男', 3, '刘四');

 -- ----------------------------
 -- Table structure for teacher
 -- ----------------------------
 DROP TABLE IF EXISTS `teacher`;
 CREATE TABLE `teacher`  (
   `tid` int(11) NOT NULL AUTO_INCREMENT,
   `tname` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
   PRIMARY KEY (`tid`) USING BTREE
 ) ENGINE = InnoDB AUTO_INCREMENT = 6 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

 -- ----------------------------
 -- Records of teacher
 -- ----------------------------
 INSERT INTO `teacher` VALUES (1, '张磊老师');
 INSERT INTO `teacher` VALUES (2, '李平老师');
 INSERT INTO `teacher` VALUES (3, '刘海燕老师');
 INSERT INTO `teacher` VALUES (4, '朱云海老师');
 INSERT INTO `teacher` VALUES (5, '李杰老师');

 SET FOREIGN_KEY_CHECKS = 1;

二.查询题

1.查询平均成绩大于60分的同学的学号和平均成绩。（由于一个同学可能选择了多个课程，我们要先查询大于60分的同学就必须分组；得到大于60分的同学；最后查询他们的学号和平均成绩）

2.查询学生的平均分，姓名，student_id;

3.根据上面的查询结果我们可以进行子查询出student_id和avg(num)