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='200'

/*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

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