T-SQL 查询、修改数据表

T-SQL修改表数据

INSERT语句

语法：

INSERT
[TOP(expression) [PERCENT]]
[INTO]
　　{ <object> | rowset_function_limited
　　　　[ WITH ( <Table_Hint_Limited> [ ...n ] ) ] /*指定表提示*/
　　　　| view_name } /*视图名*/
　　{
　　　　[(column_list) ] /*指定列名*/
　　　　[<OUTPUT Clause> ]
　　　　{VALUES /*指定列名的取值*/
　　　　　　{DEFAULT | NULL | expression}[1…n]) /*列值的构成形式*/ 　
　　　　　　　　|derived_table|execute_statement } }　/*结果集*/
　　　　|DEFAULT VALUES　/*所有列均取默认值*/

例子：

 /*插入单个元组*/
 /*向student表中插入一个学生记录（‘200’，‘曾雷’，‘女’，‘1978-2-3’，‘05001’）*/
 USE test
 INSERT INTO student_1
 VALUES(100,'曾雷','女','1995-2-3',20)

 /*查询student表，查看结果*/
 select * from student_1
 -----------------------------------------------------------------------------------

 /*向student表中插入一个学生记录（‘201’，‘孙浩’，‘男’，‘1977-8-4’，NULL）*/
 INSERT INTO student_1(sno,sname,ssex,sbirthday,sage)
 VALUES(200,'孙浩','男','1996-8-4',null)

 select * from student_1
 delete from student_1 where sno=200

 INSERT INTO student_1(sno,sname,ssex,sbirthday)
 VALUES(200,'孙浩','男','1996-8-4')
 -----------------------------------------------------------------------------------

 /*插入元组集合*/
 /*将student_1表中的相关数据插入到student表中*/
 select * from student
 select * from student_1

 insert into student(sno,sname,ssex,sage)
 select sno,sname,ssex,sage
 from student_1 

 /*向student表中添加两个新生*/
 INSERT INTO student_1(sno,sname,ssex,sbirthday,sage)
 VALUES(300,'王明','男','1996-8-4',19),(400,'赵强','男','1996-4-1',19)
 -----------------------------------------------------------------------------------

 /*向自增列添加数据*/
 create table testidentity(
 id int identity,
 words varchar(10))

 insert into testidentity values('a')  --标识列不指定
 insert into testidentity values('b')  --指定除了标识列外的列

 set IDENTITY_INSERT testidentity on
 insert into testidentity(id,words) values(10,'c')  --指定标识列

 set IDENTITY_INSERT testidentity off
 insert into testidentity values('d')

 select * from testidentity

UPDATE语句

语法：

UPDATE｛table_name｜view_name｝
SET column_name = {expression | DEFAULT | NULL}[1…n]
where where_clause

例子：

 /*将sc表中的成绩小于60的加5。*/
 UPDATE sc
 SET grade=grade+5
 WHERE grade<70

 /*将张三选修1号课程的成绩置零。*/
 UPDATE sc
 SET grade=0
 WHERE cno=1 and sno in
   (select sno from student where sname='张三')

 /*将学号为1的学生的姓名改为张三十，年龄改小2岁。*/
 UPDATE student
 SET sname='张三十',sage=sage-2   --同时更新多列
 WHERE sno=1

 select * from student
 -----------------------------------------------------------------------------------

 /*使用top表达式*/
 UPDATE top(2) student
 SET sage=sage-2  

 UPDATE top(50) percent student
 SET sage=sage-2  

DELETE语句

语法：

DELETE table_name
WHERE search_condition

例子：

 /*删除student表中学号为200的记录*/
 select * from student
 select * from sc

 DELETE student
 WHERE sno=''

 /*删除张三的选修1号课程的选课记录*/
 DELETE sc
 WHERE cno=1 and sno in
     (select sno from student where sname='张三')
 -----------------------------------------------------------------------------------

 /*TRANCATE*/
 /*TRUNCATE TABLE  table_name*/
 /*一次删除表中所有数据，即清空表，
   但表的结构及约束保持不变，且该操作不记录日志，无法恢复，使用时必须慬慎。*/

 /*删除student_1表中的记录*/
 TRUNCATE TABLE  student_1

 select * from student_1

T-SQL查询数据

SELECT 语句语法：

SELECT select_list
[INTO new_table]
FROM table_source
[WHERE search_condition]
[GROUP BY group_by_expression]
[HAVING search_condition]
[ORDER BY order_expression [ASC | DESC]]

简单查询例子：

 /*查询列*/

 /*查询student表中所有记录的sname、ssex和sage列*/
 SELECT sname,ssex,sage
 FROM student

 /*查询有选课记录的课程cno*/
 select distinct cno   --避免重复项
 from sc

 /*查询有85分以上成绩的课程cno*/
 SELECT DISTINCT cno
 FROM  sc
 WHERE grade>85

 /*查询student表的所有记录*/
 SELECT *
 FROM student

 SELECT sno as '学号',sname as '姓名',ssex as '性别'
 FROM student

 /*返回部分结果top*/
 select top(1) * from student
 select top(1) * from student where ssex='女'
 select top(1) with ties *  from student order by sage
 select top(50) percent * from student

 /*计算列*/
 select sno,sname,2015-sage as '出生年月' from student
 select sno,cno,grade*1.1 from sc
 -----------------------------------------------------

 /*选择查询

 查询sc表中成绩大于60的所有记录*/
 SELECT *
 FROM sc
 WHERE grade>60

 /*查询sc表中1号课程成绩大于60的所有记录*/
 SELECT *
 FROM sc
 WHERE cno=2 and grade>60

 /*查询score表中成绩在60～80之间的所有记录*/
 SELECT *
 FROM sc
 WHERE grade between 60 and 80

 /*查询sc表中成绩为85、86或88的记录*/
 SELECT *
 FROM sc
 WHERE grade in(85,86,88)

 /*字符串匹配*/

 /* % 匹配任意字符
    _ 匹配单个字符
   [] 匹配括号中的任意一个字符
   [^]或[!]匹配没有出现在括号中的单个字符
    escape换码字符  */

 select * from student

 /*查询student表中姓张的或性别为“女”的学生记录*/
 SELECT *
 FROM student
 WHERE sname like '张%'or ssex='女'

 /*查询student表中姓李的学生*/
 SELECT *
 FROM student
 WHERE sname like '李%'

 SELECT *
 FROM student
 WHERE sname like '[李]%'

 SELECT *
 FROM student
 WHERE sname like '李_'

 SELECT *
 FROM student
 WHERE sname like '[^李]%'

 SELECT *
 FROM student
 WHERE sname not like '[李]%'

 SELECT *
 FROM student
 WHERE sname like '%[四]%'

 /*查询sc表中没成绩的记录*/
 SELECT *
 FROM sc
 WHERE grade is null

 SELECT *
 FROM sc
 WHERE grade is not null

 /*查询结果排序*/
 SELECT *
 FROM sc
 order by grade 

 SELECT *
 FROM sc
 order by cno,grade desc

 /*分组查询*/
 /*group by group_by_expression[with rollup|cube]*
   having search_condition
   with rollup 只返回第一个分组条件制定的列的统计行;
   而with cube除返回group by制定的列外,还返回按组统计的行*/

 SELECT cno,AVG(grade)
 FROM sc
 group by cno

 SELECT cno,AVG(grade)
 FROM sc
 group by cno
 having AVG(grade)>60

 SELECT cno,tno,AVG(grade)
 FROM sc
 group by cno,tno

 SELECT cno,tno,AVG(grade)
 FROM sc
 group by cno,tno with rollup

 select AVG(grade)
 from sc

高级查询例子：

 /*嵌套查询*/
 use test

 /*使用IN或NOT IN*/
 select sname
 from student
 where sno in
     (select sno
      from sc
      where cno=2)

 select sname
 from student
 where sno not in
     (select sno
      from sc
      where cno=2)

 /*比较运算符的子查询*/

 select sno,grade
 from sc sc1
 where sc1.cno=1 and
     sc1.grade=(select sc2.grade
                 from sc sc2
                 where sc2.cno=1 and sc2.sno=1)

 select * from sc

 select sno,grade
 from sc sc1
 where sc1.cno=1 and
     sc1.grade>(select sc2.grade
                 from sc sc2
                 where sc2.cno=1 and sc2.sno=1)

 select sno
 from sc
 where cno=1 and
       grade>all(select grade from sc where sno=1)

 select sno
 from sc
 where cno=1 and
       grade>(select max(grade) from sc where sno=1)

 select student.sno,sname,cno,grade
 from sc as a,student
 where student.sno=a.sno and  --不相关子查询
     grade>(select avg(grade)
            from sc b
            where b.cno=a.cno)  

 /*exists*/
 SELECT sname
 FROM student
 WHERE EXISTS
  (SELECT *
   FROM sc
   WHERE student.sno=sc.sno and sc.cno=2)

 SELECT sname
 FROM student
 WHERE not EXISTS
  (SELECT *
   FROM sc
   WHERE student.sno=sc.sno and sc.cno=2)

 /*多层嵌套查询
 查询最高分的学生姓名*/

 select *
 from student
 where not exists
     (select *
      from course
      where not exists
         (select *
          from sc
          where sc.sno=student.sno and sc.cno=course.cno))

 select sname
 from student
 where sno in
     (select sno
      from sc
      where  grade=
         (select max(grade)
         from sc))
 go

 select * from sc
 select * from student

 /*DELETE、UPDATE和INSERT语句中的子查询*/
 ------------------------------------------------------------

 /*联接查询*/
 use test

 /*查询学生的姓名，选课号及成绩*/

 select sname,cno,grade
 from student,sc
 where student.sno=sc.sno

 select sname,cname,grade
 from student,sc,course  --多表连接
 where student.sno=sc.sno and sc.cno=course.cno

 select sname,cno,grade
 from student inner join sc on(student.sno=sc.sno) --内连接

 select student.sname,sc.cno,sc.grade
 from student left join sc on (student.sno=sc.sno)  --左向外连接

 select student.sname,sc.cno,sc.grade
 from student right join sc on (student.sno=sc.sno)   --右向外连接

 select student.sname,sc.cno,sc.grade
 from student full outer join sc on (student.sno=sc.sno)  --完全外部连接

 select student.sno,sc.sno,sc.cno,sc.grade
 from student cross join sc                  --交叉连接

 select student.sno,sc.sno,sc.cno,sc.grade
 from student cross join sc                  --带限定条件的交叉连接
 where student.sno<2

 select c1.cno,c2.cname
 from course c1,course c2    --自连接
 where c1.cpno=c2.cno
 --------------------------------------------------------------------------

 /*无法使用ntext、text或image列上直接连接表，
 但是使用substring函数在ntext、text或image列上间接联接表，如*/

 select *
 from student join sc
 on substring(student.mytext,1,2)=substring(sc.mytext,1,2)
 ------------------------------

 /*使用UNION运算符组合多个结果
 查询所有作者和客户的号码和名称*/

 select sno,sname from student where sno=1
 union
 select sno,sname from student where sno=2
 go
 ---------------------------

  /*在查询的基础上创建新表
 将查询得到的学生学号、姓名、课程和分数输入到新建的表score1中，
 再显示该新表的记录*/

 select student.sno,avg(grade) as 平均成绩
 into avggrade    --该表自动生成
 from student inner join sc on (student.sno=sc.sno)
 group by student.sno

 select * from avggrade

 drop table avggrade