SQL常用查询语句.docx

1、SQL常用查询语句SQL基本常用查询语句-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

2、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, , from student s; -column 列运算 select (age + id) col from student; select + - + from classes c, student s where = ; -where 条件 select * from student where id = 2; select * from student where id 7; s

3、elect * from student where id 3; select * from student where id 3; select * from student where id = 3; select * from student where id 3; 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

4、 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 %ao%; select * from student where name not like %a%; select * from student where name like ja%; select * from student where name not like %j,n%; s

5、elect * 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 n

6、ull; -is not null 不为空 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 分组 按照年龄进行分组统计 select count(age), age from student group by age; 按照性别进行分组统计 select count(*)

7、, sex from student group by sex; 按照年龄和性别组合分组统计，并排序 select count(*), sex from student group by sex, age order by age; 按照性别分组，并且是id大于2的记录最后按照性别排序 select count(*), sex from student where id 2 group by sex order by sex; 查询id大于2的数据，并完成运算后的结果进行分组和排序 select count(*), (sex * id) new from student where id 2

8、group by sex * id order by sex * id; -group by all 所有分组 按照年龄分组，是所有的年龄 select count(*), age from student group by all age; -having 分组过滤条件 按照年龄分组，过滤年龄为空的数据，并且统计分组的条数和现实年龄信息 select count(*), age from student group by age having age is not null; 按照年龄和cid组合分组，过滤条件是cid大于1的记录 select count(*), cid, sex from

9、 student group by cid, sex having cid 1; 按照年龄分组，过滤条件是分组后的记录条数大于等于2 select count(*), age from student group by age having count(age) = 2; 按照cid和性别组合分组，过滤条件是cid大于1，cid的最大值大于2 select count(*), cid, sex from student group by cid, sex having cid 1 and max(cid) 2; 嵌套子查询 子查询是一个嵌套在select、insert、update或delet

10、e语句或其他子查询中的查询。任何允许使用表达式的地方都可以使用子查询。子查询也称为内部查询或内部选择，而包含子查询的语句也成为外部查询或外部选择。 # from (select table)示例 将一个table的查询结果当做一个新表进行查询 select * from ( select id, name from student where sex = 1 ) t where 2; 上面括号中的语句，就是子查询语句（内部查询）。在外面的是外部查询，其中外部查询可以包含以下语句： 1、 包含常规选择列表组件的常规select查询 2、 包含一个或多个表或视图名称的常规from语句 3、 可选的

11、where子句 4、 可选的group by子句 5、 可选的having子句 # 示例 查询班级信息，统计班级学生人生 select *, (select count(*) from student where cid = as num from classes order by num; # in, not in子句查询示例 查询班级id大于小于的这些班级的学生信息 select * from student where cid in ( select id from classes where id 2 and id all ( select age from student where

12、 cid = 3 ); select * from student where cid = 5 and age any ( select age from student where cid = 3 ); select * from student where cid = 5 and age some ( select age from student where cid = 3 ); 聚合查询 1、 distinct去掉重复数据 select distinct sex from student; select count(sex), count(distinct sex) from stud

13、ent; 2、 compute和compute by汇总查询 对年龄大于的进行汇总 select age from student where age 20 order by age compute sum(age) by age; 对年龄大于的按照性别进行分组汇总年龄信息 select id, sex, age from student where age 20 order by sex, age compute sum(age) by sex; 按照年龄分组汇总 select age from student where age 20 order by age, id compute su

14、m(age); 按照年龄分组，年龄汇总，id找最大值 select id, age from student where age 20 order by age compute sum(age), max(id); compute进行汇总前面是查询的结果，后面一条结果集就是汇总的信息。compute子句中可以添加多个汇总表达式，可以添加的信息如下： a、 可选by关键字。它是每一列计算指定的行聚合 b、 行聚合函数名称。包括sum、avg、min、max、count等 c、 要对其执行聚合函数的列 compute by适合做先分组后汇总的业务。compute by后面的列一定要是order b

15、y中出现的列。 3、 cube汇总 cube汇总和compute效果类似，但语法较简洁，而且返回的是一个结果集。 select count(*), sex from student group by sex with cube; select count(*), age, sum(age) from student where age is not null group by age with cube; cube要结合group by语句完成分组汇总 排序函数 排序在很多地方需要用到，需要对查询结果进行排序并且给出序号。比如： 1、 对某张表进行排序，序号需要递增不重复的 2、 对学生的成绩

16、进行排序，得出名次，名次可以并列，但名次的序号是连续递增的 3、 在某些排序的情况下，需要跳空序号，虽然是并列 基本语法 排序函数 over(分组语句 排序子句descasc) 排序子句 order by 列名, 列名 分组子句 partition by 分组列, 分组列 # row_number函数 根据排序子句给出递增连续序号 按照名称排序的顺序递增 select , , cid, , row_number() over(order by as number from student s, classes c where cid = ; # rank函数函数 根据排序子句给出递增的序号，但

17、是存在并列并且跳空 顺序递增 select id, name, rank() over(order by cid) as rank from student; 跳过相同递增 select , , cid, , rank() over(order by as rank from student s, classes c where cid = ; # dense_rank函数 根据排序子句给出递增的序号，但是存在并列不跳空 不跳过，直接递增 select , , cid, , dense_rank() over(order by as dense from student s, classes

18、c where cid = ; # partition by分组子句 可以完成对分组的数据进行增加排序，partition by可以与以上三个函数联合使用。 利用partition by按照班级名称分组，学生id排序 select , , cid, , row_number() over(partition by order by as rank from student s, classes c where cid = ; select , , cid, , rank() over(partition by order by as rank from student s, classes c

19、 where cid = ; select , , cid, , dense_rank() over(partition by order by as rank from student s, classes c where cid = ; # ntile平均排序函数 将要排序的数据进行平分，然后按照等分排序。ntile中的参数代表分成多少等分。 select , , cid, , ntile(5) over(order by as ntile from student s, classes c where cid = ; 集合运算 操作两组查询结果，进行交集、并集、减集运算 1、 union

20、和union all进行并集运算 -union 并集、不重复 select id, name from student where name like ja% union select id, name from student where id = 4; -并集、重复 select * from student where name like ja% union all select * from student; 2、 intersect进行交集运算 -交集（相同部分） select * from student where name like ja% intersect select *

21、 from student; 3、 except进行减集运算 -减集（除相同部分） select * from student where name like ja% except select * from student where name like jas%; 公式表表达式 查询表的时候，有时候中间表需要重复使用，这些子查询被重复查询调用，不但效率低，而且可读性低，不利于理解。那么公式表表达式可以解决这个问题。 我们可以将公式表表达式（CET）视为临时结果集，在select、insert、update、delete或是create view语句的执行范围内进行定义。 -表达式 with

22、 statNum(id, num) as ( select cid, count(*) from student where id 0 group by cid ) select id, num from statNum order by id; with statNum(id, num) as ( select cid, count(*) from student where id 0 group by cid ) select max(id), avg(num) from statNum; 连接查询 1、 简化连接查询 -简化联接查询 select , , , from student s

23、, classes c where = ; 2、 left join左连接 -左连接 select , , , from student s left join classes c on = ; 3、 right join右连接 -右连接 select , , , from student s right join classes c on = ; 4、 inner join内连接 -内连接 select , , , from student s inner join classes c on = ; -inner可以省略 select , , , from student s join cl

24、asses c on = ; 5、 cross join交叉连接 -交叉联接查询，结果是一个笛卡儿乘积 select , , , from student s cross join classes c -where = ; 6、 自连接（同一张表进行连接查询） -自连接 select distinct s.* from student s, student s1 where and = ; 函数 1、 聚合函数 max最大值、min最小值、count统计、avg平均值、sum求和、var求方差 select max(age) max_age, min(age) min_age, count(a

25、ge) count_age, avg(age) avg_age, sum(age) sum_age, var(age) var_age from student; 2、 日期时间函数 select dateAdd(day, 3, getDate();-加天 select dateAdd(year, 3, getDate();-加年 select dateAdd(hour, 3, getDate();-加小时 -返回跨两个指定日期的日期边界数和时间边界数 select dateDiff(day, 2011-06-20, getDate(); -相差秒数 select dateDiff(secon

26、d, 2011-06-22 11:00:00, getDate(); -相差小时数 select dateDiff(hour, 2011-06-22 10:00:00, getDate(); select dateName(month, getDate();-当前月份 select dateName(minute, getDate();-当前分钟 select dateName(weekday, getDate();-当前星期 select datePart(month, getDate();-当前月份 select datePart(weekday, getDate();-当前星期 sele

27、ct datePart(second, getDate();-当前秒数 select day(getDate();-返回当前日期天数 select day(2011-06-30);-返回当前日期天数 select month(getDate();-返回当前日期月份 select month(2011-11-10); select year(getDate();-返回当前日期年份 select year(2010-11-10); select getDate();-当前系统日期 select getUTCDate();-utc日期 3、 数学函数 select pi();-PI函数 select

28、 rand(100), rand(50), rand(), rand();-随机数 select round(rand(), 3), round(rand(100), 5);-精确小数位 -精确位数，负数表示小数点前 select round, 2), round, -2); select round, 1, 2); 4、 元数据 select col_name(object_id(student), 1);-返回列名 select col_name(object_id(student), 2); -该列数据类型长度 select col_length(student, col_name(object_id(student), 2); -该列数据类型长度 select col_length(student, col_name(object_id(student), 1); -返回类型名称、类型id select type_name(type_id(varchar), type_i