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：
1 /*插入单个元组*/ 2 /*向student表中插入一个学生记录（‘200’，‘曾雷’，‘女’，‘1978-2-3’，‘05001’）*/ 3 USE test 4 INSERT INTO student_1 5 VALUES(100,'曾雷','女','1995-2-3',20) 6 7 /*查询student表，查看结果*/ 8 select * from student_1 9 ----------------------------------------------------------------------------------- 10 11 12 /*向student表中插入一个学生记录（‘201’，‘孙浩’，‘男’，‘1977-8-4’，NULL）*/ 13 INSERT INTO student_1(sno,sname,ssex,sbirthday,sage) 14 VALUES(200,'孙浩','男','1996-8-4',null) 15 16 select * from student_1 17 delete from student_1 where sno=200 18 19 INSERT INTO student_1(sno,sname,ssex,sbirthday) 20 VALUES(200,'孙浩','男','1996-8-4') 21 ----------------------------------------------------------------------------------- 22 23 24 /*插入元组集合*/ 25 /*将student_1表中的相关数据插入到student表中*/ 26 select * from student 27 select * from student_1 28 29 insert into student(sno,sname,ssex,sage) 30 select sno,sname,ssex,sage 31 from student_1 32 33 34 /*向student表中添加两个新生*/ 35 INSERT INTO student_1(sno,sname,ssex,sbirthday,sage) 36 VALUES(300,'王明','男','1996-8-4',19),(400,'赵强','男','1996-4-1',19) 37 ----------------------------------------------------------------------------------- 38 39 40 /*向自增列添加数据*/ 41 create table testidentity( 42 id int identity, 43 words varchar(10)) 44 45 insert into testidentity values('a') --标识列不指定 46 insert into testidentity values('b') --指定除了标识列外的列 47 48 set IDENTITY_INSERT testidentity on 49 insert into testidentity(id,words) values(10,'c') --指定标识列 50 51 set IDENTITY_INSERT testidentity off 52 insert into testidentity values('d') 53 54 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：
1 /*将sc表中的成绩小于60的加5。*/ 2 UPDATE sc 3 SET grade=grade+5 4 WHERE grade<70 5 6 /*将张三选修1号课程的成绩置零。*/ 7 UPDATE sc 8 SET grade=0 9 WHERE cno=1 and sno in 10 (select sno from student where sname='张三') 11 12 13 /*将学号为1的学生的姓名改为张三十，年龄改小2岁。*/ 14 UPDATE student 15 SET sname='张三十',sage=sage-2 --同时更新多列 16 WHERE sno=1 17 18 select * from student 19 ----------------------------------------------------------------------------------- 20 21 /*使用top表达式*/ 22 UPDATE top(2) student 23 SET sage=sage-2 24 25 UPDATE top(50) percent student 26 SET sage=sage-2
DELETE语句
语法：
DELETE table_name
WHERE search_condition
例子：
1 /*删除student表中学号为200的记录*/ 2 select * from student 3 select * from sc 4 5 DELETE student 6 WHERE sno='200' 7 8 /*删除张三的选修1号课程的选课记录*/ 9 DELETE sc 10 WHERE cno=1 and sno in 11 (select sno from student where sname='张三') 12 ----------------------------------------------------------------------------------- 13 14 /*TRANCATE*/ 15 /*TRUNCATE TABLE table_name*/ 16 /*一次删除表中所有数据，即清空表， 17 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。*/ 18 19 20 /*删除student_1表中的记录*/ 21 TRUNCATE TABLE student_1 22 23 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：
1 /*查询列*/ 2 3 /*查询student表中所有记录的sname、ssex和sage列*/ 4 SELECT sname,ssex,sage 5 FROM student 6 7 /*查询有选课记录的课程cno*/ 8 select distinct cno --避免重复项 9 from sc 10 11 /*查询有85分以上成绩的课程cno*/ 12 SELECT DISTINCT cno 13 FROM sc 14 WHERE grade>85 15 16 17 /*查询student表的所有记录*/ 18 SELECT * 19 FROM student 20 21 SELECT sno as '学号',sname as '姓名',ssex as '性别' 22 FROM student 23 24 25 /*返回部分结果top*/ 26 select top(1) * from student 27 select top(1) * from student where ssex='女' 28 select top(1) with ties * from student order by sage 29 select top(50) percent * from student 30 31 32 /*计算列*/ 33 select sno,sname,2015-sage as '出生年月' from student 34 select sno,cno,grade*1.1 from sc 35 ----------------------------------------------------- 36 37 38 /*选择查询 39 40 查询sc表中成绩大于60的所有记录*/ 41 SELECT * 42 FROM sc 43 WHERE grade>60 44 45 46 /*查询sc表中1号课程成绩大于60的所有记录*/ 47 SELECT * 48 FROM sc 49 WHERE cno=2 and grade>60 50 51 52 /*查询score表中成绩在60～80之间的所有记录*/ 53 SELECT * 54 FROM sc 55 WHERE grade between 60 and 80 56 57 58 /*查询sc表中成绩为85、86或88的记录*/ 59 SELECT * 60 FROM sc 61 WHERE grade in(85,86,88) 62 63 64 /*字符串匹配*/ 65 66 /* % 匹配任意字符 67 _ 匹配单个字符 68 [] 匹配括号中的任意一个字符 69 [^]或[!]匹配没有出现在括号中的单个字符 70 escape换码字符 */ 71 72 select * from student 73 74 /*查询student表中姓张的或性别为“女”的学生记录*/ 75 SELECT * 76 FROM student 77 WHERE sname like '张%'or ssex='女' 78 79 /*查询student表中姓李的学生*/ 80 SELECT * 81 FROM student 82 WHERE sname like '李%' 83 84 SELECT * 85 FROM student 86 WHERE sname like '[李]%' 87 88 SELECT * 89 FROM student 90 WHERE sname like '李_' 91 92 SELECT * 93 FROM student 94 WHERE sname like '[^李]%' 95 96 SELECT * 97 FROM student 98 WHERE sname not like '[李]%' 99 100 SELECT * 101 FROM student 102 WHERE sname like '%[四]%' 103 104 105 /*查询sc表中没成绩的记录*/ 106 SELECT * 107 FROM sc 108 WHERE grade is null 109 110 SELECT * 111 FROM sc 112 WHERE grade is not null 113 114 115 /*查询结果排序*/ 116 SELECT * 117 FROM sc 118 order by grade 119 120 SELECT * 121 FROM sc 122 order by cno,grade desc 123 124 125 /*分组查询*/ 126 /*group by group_by_expression[with rollup|cube]* 127 having search_condition 128 with rollup 只返回第一个分组条件制定的列的统计行; 129 而with cube除返回group by制定的列外,还返回按组统计的行*/ 130 131 SELECT cno,AVG(grade) 132 FROM sc 133 group by cno 134 135 SELECT cno,AVG(grade) 136 FROM sc 137 group by cno 138 having AVG(grade)>60 139 140 SELECT cno,tno,AVG(grade) 141 FROM sc 142 group by cno,tno 143 144 SELECT cno,tno,AVG(grade) 145 FROM sc 146 group by cno,tno with rollup 147 148 select AVG(grade) 149 from sc
高级查询例子：
1 /*嵌套查询*/ 2 use test 3 4 /*使用IN或NOT IN*/ 5 select sname 6 from student 7 where sno in 8 (select sno 9 from sc 10 where cno=2) 11 12 select sname 13 from student 14 where sno not in 15 (select sno 16 from sc 17 where cno=2) 18 19 20 /*比较运算符的子查询*/ 21 22 select sno,grade 23 from sc sc1 24 where sc1.cno=1 and 25 sc1.grade=(select sc2.grade 26 from sc sc2 27 where sc2.cno=1 and sc2.sno=1) 28 29 select * from sc 30 31 select sno,grade 32 from sc sc1 33 where sc1.cno=1 and 34 sc1.grade>(select sc2.grade 35 from sc sc2 36 where sc2.cno=1 and sc2.sno=1) 37 38 select sno 39 from sc 40 where cno=1 and 41 grade>all(select grade from sc where sno=1) 42 43 select sno 44 from sc 45 where cno=1 and 46 grade>(select max(grade) from sc where sno=1) 47 48 49 select student.sno,sname,cno,grade 50 from sc as a,student 51 where student.sno=a.sno and --不相关子查询 52 grade>(select avg(grade) 53 from sc b 54 where b.cno=a.cno) 55 56 57 /*exists*/ 58 SELECT sname 59 FROM student 60 WHERE EXISTS 61 (SELECT * 62 FROM sc 63 WHERE student.sno=sc.sno and sc.cno=2) 64 65 SELECT sname 66 FROM student 67 WHERE not EXISTS 68 (SELECT * 69 FROM sc 70 WHERE student.sno=sc.sno and sc.cno=2) 71 72 73 /*多层嵌套查询 74 查询最高分的学生姓名*/ 75 76 select * 77 from student 78 where not exists 79 (select * 80 from course 81 where not exists 82 (select * 83 from sc 84 where sc.sno=student.sno and sc.cno=course.cno)) 85 86 87 select sname 88 from student 89 where sno in 90 (select sno 91 from sc 92 where grade= 93 (select max(grade) 94 from sc)) 95 go 96 97 select * from sc 98 select * from student 99 100 101 /*DELETE、UPDATE和INSERT语句中的子查询*/ 102 ------------------------------------------------------------ 103 104 105 /*联接查询*/ 106 use test 107 108 /*查询学生的姓名，选课号及成绩*/ 109 110 select sname,cno,grade 111 from student,sc 112 where student.sno=sc.sno 113 114 select sname,cname,grade 115 from student,sc,course --多表连接 116 where student.sno=sc.sno and sc.cno=course.cno 117 118 select sname,cno,grade 119 from student inner join sc on(student.sno=sc.sno) --内连接 120 121 122 select student.sname,sc.cno,sc.grade 123 from student left join sc on (student.sno=sc.sno) --左向外连接 124 125 126 select student.sname,sc.cno,sc.grade 127 from student right join sc on (student.sno=sc.sno) --右向外连接 128 129 130 select student.sname,sc.cno,sc.grade 131 from student full outer join sc on (student.sno=sc.sno) --完全外部连接 132 133 134 select student.sno,sc.sno,sc.cno,sc.grade 135 from student cross join sc --交叉连接 136 137 select student.sno,sc.sno,sc.cno,sc.grade 138 from student cross join sc --带限定条件的交叉连接 139 where student.sno<2 140 141 142 select c1.cno,c2.cname 143 from course c1,course c2 --自连接 144 where c1.cpno=c2.cno 145 -------------------------------------------------------------------------- 146 147 /*无法使用ntext、text或image列上直接连接表， 148 但是使用substring函数在ntext、text或image列上间接联接表，如*/ 149 150 select * 151 from student join sc 152 on substring(student.mytext,1,2)=substring(sc.mytext,1,2) 153 ------------------------------ 154 155 156 /*使用UNION运算符组合多个结果 157 查询所有作者和客户的号码和名称*/ 158 159 select sno,sname from student where sno=1 160 union 161 select sno,sname from student where sno=2 162 go 163 --------------------------- 164 165 /*在查询的基础上创建新表 166 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， 167 再显示该新表的记录*/ 168 169 select student.sno,avg(grade) as 平均成绩 170 into avggrade --该表自动生成 171 from student inner join sc on (student.sno=sc.sno) 172 group by student.sno 173 174 select * from avggrade 175 176 177 drop table avggrade
