第四章：Sql高级查询.pdf

学习在于积累：滴水可以石穿！学而不思则罔，思而不学则殆！ QQ ：282624307 SQL Server T-SQL 高级查询高级查询 高级查询高级查询 高级查询在数据库中用得是最频繁的，也是应用最广泛的。 Ø 基本常用查询 --select select * from student; --all 查询所有 select all sex from student; --distinct 过滤重复 select distinct sex from student; --count 统计 select count (*) from student; select count (sex) from student; select count (distinct sex) from student; --top 取前N 条记录 select top 3 * from student; --alias column name 列重命名 select id as 编号, name 名称, sex 性别 from student; --alias table name 表重命名 select id, name, s.id, s.name from student s; --column 列运算 select (age + id) col from student; select s.name + - + c.name from classes c, student s where s.cid = c.id; --where 条件 select * from student where id = 2; select * from student where id 7; select * from student where id 3; select * from student where id 3; select * from student where id = 3; select * from student where id = 5; select * from student where id ! 3; select * from student where id ! 5; --and 并且 select * from student where id 2 and sex = 1; --or 或者 select * from student where id = 2 or sex = 1; --between ... and ... 相当于并且 select * from student where id between 2 and 5; select * from student where id not between 2 and 5; --like 模糊查询 select * from student where name like %a%; select * from student where name like %[a][o]%; select * from student where name not like %a%; select * from student where name like ja%; select * from student where name not like %[j,n]%; select * from student where name like %[j,n,a]%; select * from student where name like %[^ja,as,on]%; select * from student where name like %[ja_on]%; --in 子查询 select * from student where id in (1, 2); --not in 不在其中 select * from student where id not in (1, 2); --is null 是空 select * from student where age is null; --is not null 不为空 select * from student where age is not null; --order by 排序 select * from