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2207/MySQL练习题/查询练习.md

@@ -185,12 +185,12 @@ SELECT st.*, c1.score '01课程', c2.score '02课程'
 FROM students st, (
 	SELECT sc1.student_id, sc1.score
 	FROM scores sc1
-	WHERE sc1.course_id = 1
+	WHERE sc1.course_id = '01'
 )c1,
 (
 	SELECT sc2.student_id, sc2.score
 	FROM scores sc2
-	WHERE sc2.course_id = 2
+	WHERE sc2.course_id = '02'
 )c2
 WHERE st.id = c1.student_id AND st.id = c2.student_id AND c1.score > c2.score;
 
@@ -199,12 +199,12 @@ SELECT st.*, c1.score '01课程', c2.score '02课程'
 FROM students st, (
 	SELECT sc1.student_id, sc1.score
 	FROM scores sc1
-	WHERE sc1.course_id = 1
+	WHERE sc1.course_id = '01'
 )c1,
 (
 	SELECT sc2.student_id, sc2.score
 	FROM scores sc2
-	WHERE sc2.course_id = 2
+	WHERE sc2.course_id = '02'
 )c2
 WHERE st.id = c1.student_id AND st.id = c2.student_id;
 
@@ -215,13 +215,13 @@ LEFT JOIN
 (
 	SELECT sc1.student_id, sc1.score
 	FROM scores sc1
-	WHERE sc1.course_id = 1
+	WHERE sc1.course_id = '01'
 )c1 ON st.id = c1.student_id
 LEFT JOIN
 (
 	SELECT sc2.student_id, sc2.score
 	FROM scores sc2
-	WHERE sc2.course_id = 2
+	WHERE sc2.course_id = '02'
 )c2 ON st.id = c2.student_id 
 WHERE c1.score IS NOT NULL;
 
@@ -232,13 +232,13 @@ LEFT JOIN
 (
 	SELECT sc1.student_id, sc1.score
 	FROM scores sc1
-	WHERE sc1.course_id = 1
+	WHERE sc1.course_id = '01'
 )c1 ON st.id = c1.student_id
 LEFT JOIN
 (
 	SELECT sc2.student_id, sc2.score
 	FROM scores sc2
-	WHERE sc2.course_id = 2
+	WHERE sc2.course_id = '02'
 )c2 ON st.id = c2.student_id 
 WHERE c1.score IS NULL AND c2.score IS NOT NULL;
 
@@ -256,14 +256,72 @@ WHERE students.id IN (
 	SELECT student_id
 	FROM scores
 );
-
 #4.查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )
+SELECT st.id, st.`name`, COUNT(*), SUM(sc.score)
+FROM students st
+LEFT JOIN scores sc ON st.id = sc.student_id
+GROUP BY st.id;
 #4.1查有成绩的学生信息
+SELECT st.id, st.`name`, COUNT(*), SUM(sc.score)
+FROM students st
+LEFT JOIN scores sc ON st.id = sc.student_id
+WHERE sc.score IS NOT NULL
+GROUP BY st.id;
 
 #5.查询「李」姓老师的数量
+SELECT COUNT(*)
+FROM teachers t
+WHERE t.`name` LIKE '李%';
 
 #6.查询学过「张三」老师授课的同学的信息
+SELECT st.*
+FROM students st, scores sc
+WHERE st.id = sc.student_id AND sc.course_id = (
+	SELECT c.id
+	FROM courses c, teachers t
+	WHERE c.teacher_id = t.id AND t.`name` = '张三'
+);
 
 #7.查询没有学全所有课程的同学的信息
+SELECT st.*
+FROM students st
+LEFT JOIN scores sc ON st.id = sc.student_id
+LEFT JOIN courses c ON sc.course_id = c.id
+GROUP BY st.id
+HAVING COUNT(*) < 3;
+
+#8.查询至少有一门课与学号为" 01 "的同学所学相同的同学的信息
+SELECT st.*
+FROM students st, scores sc
+WHERE st.id = sc.student_id AND sc.course_id IN(
+	SELECT
+	FROM courses
+	WHERE student_id = '01'
+);
+
+#9.查询和" 01 "号的同学学习的课程完全相同的其他同学的信息
+SELECT st.* 
+FROM students st, scores sc
+WHERE st.id = sc.student_id AND sc.course_id AND st.id <> '01'
+GROUP BY st.id
+HAVING GROUP_CONCAT(sc.course_id) = (
+	SELECT GROUP_CONCAT(c.course_id)
+	FROM scores c
+	WHERE c.student_id = '01'
+);
+
+#10.查询没学过"张三"老师讲授的任一门课程的学生姓名
+
+#11.查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
+
+#12.检索" 01 "课程分数小于 60，按分数降序排列的学生信息
+
+#13.按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
+
+#14.查询各科成绩最高分、最低分和平均分：以如下形式显示：课程 ID，课程 name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率；（及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90）
+
+#15.按各科成绩进行排序，并显示排名， Score 重复时保留名次空缺
+
+#15.1按各科成绩进行排序，并显示排名， Score 重复时合并名次
 ```