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HomeDatabaseMysql TutorialSQL Server 数据查询 --- 复杂查询

SQL Server 数据查询 --- 复杂查询 有需要的朋友可参考一下。

/********************************************

例1查询每个学生及其选修课程的情况

*********************************************/

 代码如下 复制代码

SELECT STUDENT.*,SC.* FROM SC,STUDENT WHERE SC.SNO = STUDENT.SNO;

/********************************************

对例1用自然连接完成

*********************************************/

 代码如下 复制代码
 SELECT STUDENT.SNAME,STUDENT.SSEX,STUDENT.SAGE,STUDENT.SDEPT,SC.*
 FROM SC,STUDENT       
 WHERE SC.SNO = STUDENT.SNO;

/*****************************************

查询每一门课程的间接先修课

*****************************************/

 

 代码如下 复制代码
SELECT SY.CNO,SX.CPNO FROM COURSE SX,COURSE SY WHERE SX.CNO = SY.CPNO

/********************************************

对例1用左外连接连接完成

*********************************************/

 代码如下 复制代码
 SELECT STUDENT.SNAME,STUDENT.SSEX,STUDENT.SAGE,STUDENT.SDEPT,SC.*
 FROM   STUDENT LEFT JOIN SC ON(SC.SNO = STUDENT.SNO);

/********************************************

查询每个学生的学号、姓名、选修的课程名及成绩 *********************************************/

 代码如下 复制代码

 SELECT STUDENT.SNO,STUDENT.SNAME,COURSE.CNAME,COURSE.CCREDIT
 FROM SC,STUDENT,COURSE   
 WHERE SC.CNO =COURSE.CNO AND SC.SNO = STUDENT.SNO;

/********************************************  

查询与刘晨在同一个系学习的学生

*********************************************/

 代码如下 复制代码

 SELECT SX.*
 FROM STUDENT SX   
 WHERE SX.SDEPT IN  (
              SELECT SY.SDEPT FROM STUDENT SY WHERE SY.SNAME='刘晨'
 );
/************   

或者如下:

 代码如下 复制代码

 SELECT SX.*
 FROM STUDENT SX, STUDENT SY      
 WHERE SX.SDEPT = SY.SDEPT AND SY.SNAME = '刘晨';  或者:

 SELECT *
 FROM STUDENT SX
 WHERE EXISTS (
          SELECT * FROM STUDENT SY WHERE SY.SDEPT = SX.SDEPT AND SY.SNAME='刘晨'
 );  **************/

 

/********************************************  

查询选修了课程名为"信息系统"的学生学号和姓名 *********************************************/

 

 代码如下 复制代码
 SELECT SNO, SNAME
 FROM STUDENT       
 WHERE SNO IN  (
         SELECT SNO FROM SC
         WHERE  CNO IN  (
                     SELECT CNO FROM COURSE
                     WHERE CNAME = '信息系统'
                    )
 );  

/********************************************  

找出每个学生超过他选修课程平均成绩的课程号

*********************************************/

 

 代码如下 复制代码

SELECT SX.SNO,SX.CNO
 FROM SC SX
 WHERE SX.GRADE  >  (
                        SELECT AVG(GRADE)
                       FROM SC SY              
                        WHERE SX.SNO = SY.SNO
);

/*****************************************************  

查询其他系中比计算机科学系某一学生年龄小的学生姓名和年龄

*******************************************************/

 代码如下 复制代码


 SELECT SNAME, SAGE
 FROM STUDENT   
 WHERE SAGE                        SELECT SAGE
                       FROM STUDENT 
                       WHERE SDEPT='CS'
                    )
       AND SDEPT'CS';

/*****************************************************  

查询其他系中比计算机科学系所有学生年龄小的学生姓名和年龄

*******************************************************/

 代码如下 复制代码

 SELECT SNAME, SAGE
 FROM STUDENT   
 WHERE SAGE                        SELECT SAGE
                      FROM STUDENT 
                       WHERE SDEPT='CS' 
                    )
       AND SDEPT'CS';

/*****************************************************  

查询所有选修了1号课程的学生姓名

*******************************************************/

 代码如下 复制代码


 SELECT SNAME
 FROM STUDENT   
 WHERE EXISTS   (
                   SELECT * FROM SC           
                   WHERE SC.SNO = STUDENT.SNO AND SC.CNO='1'          
 );

/******************************************

查询选修了全部课程的学生姓名

*******************************************/

 代码如下 复制代码

 SELECT SNAME
 FROM STUDENT
 WHERE NOT EXISTS (
                     SELECT *
                     FROM COURSE
                     WHERE NOT EXISTS   (
                                           SELECT *
                                           FROM SC
                                           WHERE STUDENT.SNO = SC.SNO AND COURSE.CNO = SC.CNO
                                        )
 );

/*****************************************************

查询至少选修了学生200215122选修的全部课程的学生号码

*****************************************************/

 代码如下 复制代码

 SELECT DISTINCT SNO
 FROM SC X    
 WHERE NOT EXISTS (
                     SELECT *
                     FROM SC Y
                    WHERE SNO='200215122' AND NOT EXISTS (
                                                            SELECT *
                                                            FROM SC Z
                                                             WHERE Z.SNO = X.SNO AND Y.CNO = Z.CNO             
                                                           )
 );

/**********************************************************

从自身表中选择一条记录,修改某个字段再回插到自身表中

这里的INSERT INTO 可以用来插入子查询 *********************************************************/

 代码如下 复制代码

 INSERT INTO COURSE(CNO,CNAME,CPNO,CCREDIT)
       SELECT '8',CNAME,CPNO,CCREDIT FROM  COURSE WHERE  CNO='2';

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