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_1delete from student_1 where sno=200INSERT 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 studentselect * from student_1insert 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 scSET grade=grade+5WHERE grade<70/*将张三选修1号课程的成绩置零。*/UPDATE scSET grade=0WHERE 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 studentSET sname='张三十',sage=sage-2   --同时更新多列WHERE sno=1select * from student-----------------------------------------------------------------------------------/*使用top表达式*/UPDATE top(2) studentSET sage=sage-2  UPDATE top(50) percent studentSET 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 studentselect * from scDELETE 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_1select * 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,sageFROM 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 cnoFROM  sc WHERE grade>85/*查询student表的所有记录*/SELECT *FROM studentSELECT 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 studentselect top(1) * from student where ssex='女'select top(1) with ties *  from student order by sageselect top(50) percent * from student/*计算列*/select sno,sname,2015-sage as '出生年月' from studentselect 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 scWHERE grade>60/*查询sc表中1号课程成绩大于60的所有记录*/SELECT *FROM scWHERE cno=2 and grade>60/*查询score表中成绩在60～80之间的所有记录*/SELECT *FROM scWHERE grade between 60 and 80/*查询sc表中成绩为85、86或88的记录*/SELECT *FROM scWHERE 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 studentWHERE sname like '张%'or ssex='女'/*查询student表中姓李的学生*/SELECT *FROM studentWHERE sname like '李%'SELECT *FROM studentWHERE sname like '[李]%'SELECT *FROM studentWHERE sname like '李_'SELECT *FROM studentWHERE sname like '[^李]%'SELECT *FROM studentWHERE sname not like '[李]%'SELECT *FROM studentWHERE sname like '%[四]%'/*查询sc表中没成绩的记录*/SELECT *FROM scWHERE grade is nullSELECT *FROM scWHERE grade is not null/*查询结果排序*/SELECT *FROM scorder by grade SELECT *FROM scorder 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 scgroup by cnoSELECT cno,AVG(grade)FROM scgroup by cnohaving AVG(grade)>60SELECT cno,tno,AVG(grade)FROM scgroup by cno,tnoSELECT cno,tno,AVG(grade)FROM scgroup by cno,tno with rollupselect AVG(grade)from sc

高级查询例子：

/*嵌套查询*/use test/*使用IN或NOT IN*/select snamefrom studentwhere sno in    (select sno      from sc     where cno=2)select snamefrom studentwhere sno not in    (select sno      from sc     where cno=2)         /*比较运算符的子查询*/select sno,gradefrom sc sc1where sc1.cno=1 and     sc1.grade=(select sc2.grade                 from sc sc2                 where sc2.cno=1 and sc2.sno=1)                select * from scselect sno,gradefrom sc sc1where sc1.cno=1 and     sc1.grade>(select sc2.grade                 from sc sc2                 where sc2.cno=1 and sc2.sno=1)                select snofrom sc where cno=1 and       grade>all(select grade from sc where sno=1)      select snofrom sc where cno=1 and       grade>(select max(grade) from sc where sno=1)            select student.sno,sname,cno,gradefrom sc as a,studentwhere 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 snameFROM student WHERE EXISTS (SELECT *  FROM sc  WHERE student.sno=sc.sno and sc.cno=2)  SELECT snameFROM 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 studentwhere not exists    (select *      from course     where not exists        (select *          from sc         where sc.sno=student.sno and sc.cno=course.cno))select snamefrom studentwhere sno in    (select sno     from sc     where  grade=        (select max(grade)        from sc))goselect * from scselect * 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,gradefrom student,sc where student.sno=sc.snoselect sname,cname,grade from student,sc,course  --多表连接where student.sno=sc.sno and sc.cno=course.cnoselect sname,cno,gradefrom student inner join sc on(student.sno=sc.sno) --内连接select student.sname,sc.cno,sc.gradefrom student left join sc on (student.sno=sc.sno)  --左向外连接select student.sname,sc.cno,sc.gradefrom student right join sc on (student.sno=sc.sno)   --右向外连接select student.sname,sc.cno,sc.gradefrom 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<2select c1.cno,c2.cnamefrom 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 scon 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=1unionselect sno,sname from student where sno=2go--------------------------- /*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.snoselect * from avggradedrop table avggrade

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