diff --git "a/45\347\216\213\345\274\272/23307\344\275\234\344\270\232.md" "b/45\347\216\213\345\274\272/23307\344\275\234\344\270\232.md"
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+```mysql
+
+```
+
+
diff --git "a/45\347\216\213\345\274\272/\344\275\234\344\270\232.md" "b/45\347\216\213\345\274\272/\344\275\234\344\270\232.md"
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+```mysql
+SHOW DATABASES;
+CREATE DATABASE mxdx charset utf8;
+USE mxdx;
+CREATE DATABASE sb charset utf8;
+USE sb;
+CREATE TABLE student (
+	sno VARCHAR ( 20 ) NOT NULL,
+	sname VARCHAR ( 20 ) NOT NULL,
+	ssex VARCHAR ( 20 ) NOT NULL,
+	sbirthday DATETIME,
+	class VARCHAR ( 20 ) 
+);
+CREATE TABLE course ( cno VARCHAR ( 20 ) NOT NULL, cname VARCHAR ( 20 ) NOT NULL, tno VARCHAR ( 20 ) NOT NULL );
+ALTER TABLE course ADD FOREIGN KEY ( tno ) REFERENCES teacher ( tno );
+CREATE TABLE score ( sno VARCHAR ( 20 ) NOT NULL, cno VARCHAR ( 20 ) NOT NULL, degree DECIMAL ( 4, 1 ) );
+CREATE TABLE teacher (
+	tno VARCHAR ( 20 ) NOT NULL PRIMARY KEY,
+	tname VARCHAR ( 20 ) NOT NULL,
+	tsex VARCHAR ( 20 ) NOT NULL,
+	tbirthday DATETIME,
+	prof VARCHAR ( 20 ),
+	depart VARCHAR ( 20 ) NOT NULL 
+);
+INSERT INTO student
+VALUES
+	( 108, '曾华', '男', '1977-9-1', 95033 ),
+	( 105, '匡明', '男', '1975-10-2', 95031 ),
+	( 107, '王丽', '女', '1976-1-23', 95033 ),
+	( 101, '李军', '男', '1976-2-20', 95033 ),
+	( 109, '王芳', '女', '1975-2-10', 95031 ),
+	( 103, '陆军', '男', '1974-6-3', 95031 );
+INSERT INTO course
+VALUES
+	( 3-105, '计算机导论', 825 ),
+	( 3-245, '操作系统', 804 ),
+	( 6-166, '数字电路', 856 ),
+	( 9-888, '高等数学', 831 );
+PRIMARY KEY ( Sno, Cno ),
+KEY Cno ( Cno ),
+CONSTRAINT Cno FOREIGN KEY ( Cno ) REFERENCES course ( Cno ),
+CONSTRAINT Sno FOREIGN KEY ( Sno ) REFERENCES student ( Sno ) 
+) ENGINE = INNODB DEFAULT CHARSET = utf8;
+INSERT INTO Score
+VALUES
+	( '103', '3-245', '86' ),
+	( '105', '3-245', '75' ),
+	( '109', '3-245', '68' ),
+	( '103', '3-105', '92' ),
+	( '105', '3-105', '88' ),
+	( '109', '3-105', '76' ),
+	( '101', '3-105', '64' ),
+	( '107', '3-105', '91' ),
+	( '108', '3-105', '78' ),
+	( '101', '6-166', '85' ),
+	( '107', '6-166', '79' ),
+	( '108', '6-166', '81' );
+CREATE TABLE Teacher (
+	Tno VARCHAR ( 20 ) NOT NULL PRIMARY KEY,
+	Tname VARCHAR ( 20 ) NOT NULL,
+	Tsex VARCHAR ( 20 ) NOT NULL,
+	Tbirthday DATETIME,
+	Prof VARCHAR ( 20 ),
+	Depart VARCHAR ( 20 ) 
+);
+INSERT INTO Teacher
+VALUES
+	( '804', '李诚', '男', '1958-12-2', '副教授', '计算机系' ),
+	( '856', '张旭', '男', '1969-3-12', '讲师', '电子工程系' ),
+	( '825', '王萍', '女', '1972-5-5', '助教', '计算机系' ),
+	( '831', '刘冰', '女', '1977-8-14', '助教', '电子工程系' );-- 4.	查询
+-- ①　查询Score表中的最高分的学生学号和课程号。
+SELECT
+	max( degree ) sno,
+	cno 
+FROM
+	score;-- ②　查询所有学生的Sname、Cno和Degree列。
+SELECT
+	sname 姓名,
+	cno,
+	degree 
+FROM
+	student,
+	score;-- ③　查询所有学生的Sno、Cname和Degree列。
+SELECT
+	sno,
+	cname,
+	degree 
+FROM
+	course,
+	score;-- ④　查询所有学生的Sname、Cname和Degree列。
+SELECT
+	sname 姓名,
+	cname,
+	degree 
+FROM
+	course,
+	score,
+	student;-- ⑤　查询“95033”班学生的平均分。
+SELECT
+	avg( degree ) 
+FROM
+	student,
+	score 
+WHERE
+	class = 95033;-- ⑥　查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。
+SELECT
+	* 
+FROM
+	score 
+WHERE
+	cno = '3-105' 
+	AND degree > 76;-- ⑦　查询score中选学多门课程的同学中分数为非最高分成绩的记录。
+( SELECT max( degree ) FROM score );
+SELECT
+	degree 
+FROM
+	score 
+WHERE
+	degree != ( SELECT max( degree ) FROM score ) 
+GROUP BY
+	Degree;-- ⑧　查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。
+SELECT
+	* 
+FROM
+	student s,
+	score se 
+WHERE
+	s.Sno = se.Sno 
+	AND degree > ( SELECT degree FROM score WHERE sno = '109' AND cno = '3-105' );-- ⑨　查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
+SELECT YEAR
+	( sbirthday ) 
+FROM
+	student 
+WHERE
+	sno = '108';
+SELECT
+	sno,
+	sname,
+	sbirthday 
+FROM
+	student 
+WHERE
+	YEAR ( sbirthday )=(
+	SELECT YEAR
+		( sbirthday ) 
+	FROM
+		student 
+	WHERE
+		sno = '108' 
+	);-- ⑩　查询“张旭“教师任课的学生成绩。
+SELECT
+	* 
+FROM
+	teacher 
+WHERE
+	Tname = '张旭';
+SELECT
+	degree 
+FROM
+	teacher t,
+	course c,
+	score s 
+WHERE
+	t.tno = c.Tno 
+	AND c.cno = s.cno 
+	AND t.tname = '张旭';-- 11　查询选修某课程的同学人数多于5人的教师姓名。
+SELECT
+	s.cno 
+FROM
+	teacher t,
+	course c,
+	score s 
+WHERE
+	t.tno = c.Tno 
+	AND c.cno = s.cno 
+GROUP BY
+	c.cno 
+HAVING
+	count( s.Cno )> 5;-- 12　查询出“计算机系“教师所教课程的成绩表。
+SELECT
+	tname,
+	prof 
+FROM
+	teacher 
+WHERE
+	depart = '计算机系' UNION
+SELECT
+	tname,
+	prof 
+FROM
+	teacher 
+WHERE
+	depart = '电子工程系';-- 13　查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。
+SELECT
+	degree 
+FROM
+	score 
+WHERE
+	cno = '3-245';
+SELECT
+	* 
+FROM
+	score 
+WHERE
+	Cno = '3-105' 
+	AND degree >= ALL ( SELECT degree FROM score WHERE cno = '3-245' ) 
+ORDER BY
+	degree DESC;-- 14　查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。
+SELECT
+	* 
+FROM
+	score 
+WHERE
+	cno = '3-105' 
+	AND degree > ALL ( SELECT degree FROM score WHERE cno = '3-245' );-- 16　查询成绩比该课程平均成绩低的同学的成绩表。
+SELECT
+	avg( degree ) 
+FROM
+	score;
+SELECT
+	degree 
+FROM
+	score 
+WHERE
+	degree < ( SELECT avg( degree ) FROM score );-- 17　查询所有任课教师的Tname和Depart.
+SELECT
+	tname,
+	depart 
+FROM
+	teacher;-- 18　查询所有未讲课的教师的Tname和Depart.
+SELECT
+	tname,
+	depart 
+FROM
+	teacher
+	LEFT JOIN course c ON teacher.tno = c.tno
+	LEFT JOIN score s ON c.cno = s.cno 
+WHERE
+	sno IS NULL;-- 19　查询“男”教师及其所上的课程。
+SELECT
+	t.*,
+	c.cname 
+FROM
+	teacher t,
+	course c 
+WHERE
+	t.tno = c.tno 
+	AND t.tsex = '男';-- 20　查询最高分同学的Sno、Cno和Degree列。
+SELECT
+	* 
+FROM
+	score 
+WHERE
+	degree =(
+	SELECT
+		max( fegree ) 
+	FROM
+		score 
+	);-- 21　查询和“李军”同性别的所有同学的Sname.
+SELECT
+	sname 
+FROM
+	student 
+WHERE
+	ssex = ( SELECT ssex FROM student WHERE sname = '李军' );-- 22　查询和“李军”同性别并同班的同学Sname.
+SELECT
+	sname 
+FROM
+	student 
+WHERE
+	ssex = ( SELECT ssex FROM student WHERE sname = '李军' ) 
+	AND class =(
+	SELECT
+		class 
+	FROM
+		student 
+	WHERE
+		sname = '李军' 
+	);-- 23　查询所有选修“计算机导论”课程的“男”同学的成绩表
+SELECT
+	ssex,
+	cname,
+	degree 
+FROM
+	student s,
+	course c,
+	score se 
+WHERE
+	s.sno = se.sno 
+	AND se.cno = c.cno 
+	AND cname = '计算机导论' 
+	AND ssex = '男';
+```