SQL Server T-SQL進階查詢

標籤：

進階查詢在資料庫中用得是最頻繁的，也是應用最廣泛的。

Ø 基本常用查詢

--select

select * from student;

--all 查詢所有

select all sex from student;

--distinct 過濾重複

select distinct sex from student;

--count 統計

select count(*) from student;

select count(sex) from student;

select count(distinct sex) from student;

--top 取前N條記錄

select top 3 * from student;

--alias column name 列重新命名

select id as 編號, name ‘名稱‘, sex 性別 from student;

--alias table name 表重新命名

select id, name, s.id, s.name from student s;

--column 列運算

select (age + id) col from student;

select s.name + ‘-‘ + c.name from classes c, student s where s.cid = c.id;

 

--where 條件

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 並且

select * from student where id > 2 and sex = 1;

--or 或者

select * from student where id = 2 or sex = 1;

--between ... and ... 相當於並且

select * from student where id between 2 and 5;

select * from student where id not between 2 and 5;

--like 模糊查詢

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 子查詢

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 不為空白

select * from student where age is not null;

--order by 排序

select * from student order by name;

select * from student order by name desc;

select * from student order by name asc;

--group by 分組

按照年齡進行分組統計

select count(age), age from student group by age;

按照性別進行分組統計

select count(*), sex from student group by sex;

按照年齡和性別組合分組統計，並排序

select count(*), sex from student group by sex, age order by age;

按照性別分組，並且是id大於2的記錄最後按照性別排序

select count(*), sex from student where id > 2 group by sex order by sex;

查詢id大於2的資料，並完成運算後的結果進行分組和排序

select count(*), (sex * id) new from student where id > 2 group by sex * id order by sex * id;

 

--group by all 所有分組

按照年齡分組，是所有的年齡

select count(*), age from student group by all age;

--having 分組過濾條件

按照年齡分組，過濾年齡為空白的資料，並且統計分組的條數和現實年齡資訊

select count(*), age from student group by age having age is not null;

按照年齡和cid組合分組，過濾條件是cid大於1的記錄

select count(*), cid, sex from student group by cid, sex having cid > 1;

按照年齡和cid組合分組，過濾條件是cid大於1的記錄

select count(*), cid, sex from student group by cid, sex having cid > 1;

按照年齡分組，過濾條件是分組後的記錄條數大於等於2

select count(*), age from student group by age having count(age) >= 2;

按照cid和性別組合分組，過濾條件是cid大於1，cid的最大值大於2

select count(*), cid, sex from student group by cid, sex having cid > 1 and max(cid) > 2;

SQL Server T-SQL進階查詢