转自：http://www.cnblogs.com/hoojo/archive/2011/07/16/2108129.html
高级查询在数据库中用得是最频繁的，也是应用最广泛的。
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 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(*), 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 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; --按照性别和cid组合分组，过滤条件是cid大于1的记录 select count(*), cid, sex from 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;
子查询是一个嵌套在select、insert、update或delete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 t.id > 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 = classes.id) as num from classes order by num;
# in, not in子句查询示例
--查询班级id大于2小于4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 < 4 ); --查询不是2班的学生信息 select * from student where cid not in ( select id from classes where name = ‘2班‘ )
in、not in 后面的子句返回的结果必须是一列，这一列的结果将会作为查询条件对应前面的条件。如cid对应子句的id；
# exists和not exists子句查询示例
--查询存在班级id为3的学生信息 select * from student where exists ( select * from classes where id = student.cid and id = 3 ); --查询没有分配班级的学生信息 select * from student where not exists ( select * from classes where id = student.cid );
exists和not exists查询需要内部查询和外部查询进行一个关联的条件，如果没有这个条件将是查询到的所有信息。如：id等于student.id；
# some、any、all子句查询示例
--查询班级的学生年龄大于班级的学生的年龄的信息 select * from student where cid = 5 and age > all ( select age from student where 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 );
1、 distinct去掉重复数据
select distinct sex from student; select count(sex), count(distinct sex) from student;
2、 compute和compute by汇总查询
--对年龄大于20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 sum(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 by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[desc][asc])
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 s.id, s.name, cid, c.name, row_number() over(order by c.name) as number from student s, classes c where cid = c.id;
# rank函数
根据排序子句给出递增的序号，但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 s.id, s.name, cid, c.name, rank() over(order by c.name) as rank from student s, classes c where cid = c.id;
# 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 s.id, s.name, cid, c.name, dense_rank() over(order by c.name) as dense from student s, classes c where cid = c.id;
# 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 s.id, s.name, cid, c.name, row_number() over(partition by c.name order by s.id) as rank from student s, classes c where cid = c.id; select s.id, s.name, cid, c.name, rank() over(partition by c.name order by s.id) as rank from student s, classes c where cid = c.id; select s.id, s.name, cid, c.name, dense_rank() over(partition by c.name order by s.id) as rank from student s, classes c where cid = c.id;
# 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 s.id, s.name, cid, c.name, ntile(5) over(order by c.name) as ntile from student s, classes c where cid = c.id;
操作两组查询结果，进行交集、并集、减集运算
1、 union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 * from student;
3、 except进行减集运算
交集（除相同部分）
select * from student where name like ‘ja%‘ except select * from student where name like ‘jas%‘;
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 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;
1、 简化连接查询
select s.id, s.name, c.id, c.name
from student s, classes c
where s.cid = c.id;
2、 left join左连接
select s.id, s.name, c.id, c.name
from student s
left join classes c on s.cid = c.id;
3、 right join右连接
select s.id, s.name, c.id, c.name from student s right join classes c on s.cid = c.id;
4、 inner join内连接
select s.id, s.name, c.id, c.name from student s inner join classes c on s.cid = c.id;
inner可以省略
select s.id, s.name, c.id, c.name from student s join classes c on s.cid = c.id;
5、 cross join交叉连接
交叉联接查询，结果是一个笛卡儿乘积
select s.id, s.name, c.id, c.name from student s cross join classes c --where s.cid = c.id;
6、 自连接（同一张表进行连接查询）
select distinct s.* from student s, student s1 where s.id <> s1.id and s.sex = s1.sex;
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(age) 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(second, ‘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 select 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 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(123.456, 2), round(254.124, -2); select round(123.4567, 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_id(‘varchar‘);
返回列类型长度
select columnProperty(object_id(‘student‘), ‘name‘, ‘PRECISION‘);
返回列所在索引位置
select columnProperty(object_id(‘student‘), ‘sex‘, ‘ColumnId‘);
5、 字符串函数
select ascii(‘a‘);--字符转换ascii值 select ascii(‘A‘); select char(97);--ascii值转换字符 select char(65); select nchar(65); select nchar(45231); select nchar(32993);--unicode转换字符 select unicode(‘A‘), unicode(‘中‘);--返回unicode编码值 select soundex(‘hello‘), soundex(‘world‘), soundex(‘word‘); select patindex(‘%a‘, ‘ta‘), patindex(‘%ac%‘, ‘jack‘), patindex(‘dex%‘, ‘dexjack‘);--匹配字符索引 select ‘a‘ + space(2) + ‘b‘, ‘c‘ + space(5) + ‘d‘;--输出空格 select charIndex(‘o‘, ‘hello world‘);--查找索引 select charIndex(‘o‘, ‘hello world‘, 6);--查找索引 select quoteName(‘abc[]def‘), quoteName(‘123]45‘); --精确数字 select str(123.456, 2), str(123.456, 3), str(123.456, 4); select str(123.456, 9, 2), str(123.456, 9, 3), str(123.456, 6, 1), str(123.456, 9, 6); select difference(‘hello‘, ‘helloWorld‘);--比较字符串相同 select difference(‘hello‘, ‘world‘); select difference(‘hello‘, ‘llo‘); select difference(‘hello‘, ‘hel‘); select difference(‘hello‘, ‘hello‘); select replace(‘abcedef‘, ‘e‘, ‘E‘);--替换字符串 select stuff(‘hello world‘, 3, 4, ‘ABC‘);--指定位置替换字符串 select replicate(‘abc#‘, 3);--重复字符串 select subString(‘abc‘, 1, 1), subString(‘abc‘, 1, 2), subString(‘hello Wrold‘, 7, 5);--截取字符串 select len(‘abc‘);--返回长度 select reverse(‘sqlServer‘);--反转字符串 select left(‘leftString‘, 4);--取左边字符串 select left(‘leftString‘, 7); select right(‘leftString‘, 6);--取右边字符串 select right(‘leftString‘, 3); select lower(‘aBc‘), lower(‘ABC‘);--小写 select upper(‘aBc‘), upper(‘abc‘);--大写 --去掉左边空格 select ltrim(‘ abc‘), ltrim(‘# abc#‘), ltrim(‘ abc‘); --去掉右边空格 select rtrim(‘ abc ‘), rtrim(‘# abc# ‘), rtrim(‘abc‘);
6、 安全函数
select current_user; select user; select user_id(), user_id(‘dbo‘), user_id(‘public‘), user_id(‘guest‘); select user_name(), user_name(1), user_name(0), user_name(2); select session_user; select suser_id(‘sa‘); select suser_sid(), suser_sid(‘sa‘), suser_sid(‘sysadmin‘), suser_sid(‘serveradmin‘); select is_member(‘dbo‘), is_member(‘public‘); select suser_name(), suser_name(1), suser_name(2), suser_name(3); select suser_sname(), suser_sname(0x01), suser_sname(0x02), suser_sname(0x03); select is_srvRoleMember(‘sysadmin‘), is_srvRoleMember(‘serveradmin‘); select permissions(object_id(‘student‘)); select system_user; select schema_id(), schema_id(‘dbo‘), schema_id(‘guest‘); select schema_name(), schema_name(1), schema_name(2), schema_name(3);
7、 系统函数
select app_name();--当前会话的应用程序名称 select cast(2011 as datetime), cast(‘10‘ as money), cast(‘0‘ as varbinary);--类型转换 select convert(datetime, ‘2011‘);--类型转换 select coalesce(null, ‘a‘), coalesce(‘123‘, ‘a‘);--返回其参数中第一个非空表达式 select collationProperty(‘Traditional_Spanish_CS_AS_KS_WS‘, ‘CodePage‘); select current_timestamp;--当前时间戳 select current_user; select isDate(getDate()), isDate(‘abc‘), isNumeric(1), isNumeric(‘a‘); select dataLength(‘abc‘); select host_id(); select host_name(); select db_name(); select ident_current(‘student‘), ident_current(‘classes‘);--返回主键id的最大值 select ident_incr(‘student‘), ident_incr(‘classes‘);--id的增量值 select ident_seed(‘student‘), ident_seed(‘classes‘); select @@identity;--最后一次自增的值 select identity(int, 1, 1) as id into tab from student;--将studeng表的烈属，以/1自增形式创建一个tab select * from tab; select @@rowcount;--影响行数 select @@cursor_rows;--返回连接上打开的游标的当前限定行的数目 select @@error;--T-SQL的错误号 select @@procid;
8、 配置函数
set datefirst 7;--设置每周的第一天，表示周日 select @@datefirst as ‘星期的第一天‘, datepart(dw, getDate()) AS ‘今天是星期‘; select @@dbts;--返回当前数据库唯一时间戳 set language ‘Italian‘; select @@langId as ‘Language ID‘;--返回语言id select @@language as ‘Language Name‘;--返回当前语言名称 select @@lock_timeout;--返回当前会话的当前锁定超时设置（毫秒） select @@max_connections;--返回SQL Server 实例允许同时进行的最大用户连接数 select @@MAX_PRECISION AS ‘Max Precision‘;--返回decimal 和numeric 数据类型所用的精度级别 select @@SERVERNAME;--SQL Server 的本地服务器的名称 select @@SERVICENAME;--服务名 select @@SPID;--当前会话进程id select @@textSize; select @@version;--当前数据库版本信息
9、 系统统计函数
select @@CONNECTIONS;--连接数 select @@PACK_RECEIVED; select @@CPU_BUSY; select @@PACK_SENT; select @@TIMETICKS; select @@IDLE; select @@TOTAL_ERRORS; select @@IO_BUSY; select @@TOTAL_READ;--读取磁盘次数 select @@PACKET_ERRORS;--发生的网络数据包错误数 select @@TOTAL_WRITE;--sqlserver执行的磁盘写入次数 select patIndex(‘%soft%‘, ‘microsoft SqlServer‘); select patIndex(‘soft%‘, ‘software SqlServer‘); select patIndex(‘%soft‘, ‘SqlServer microsoft‘); select patIndex(‘%so_gr%‘, ‘Jsonisprogram‘);
10、 用户自定义函数
# 查看当前数据库所有函数
查询所有已创建函数
select definition,* from sys.sql_modules m join sys.objects o on m.object_id = o.object_id and type in(‘fn‘, ‘if‘, ‘tf‘);
创建函数
if (object_id(‘fun_add‘, ‘fn‘) is not null) drop function fun_add go create function fun_add(@num1 int, @num2 int) returns int with execute as caller as begin declare @result int; if (@num1 is null) set @num1 = 0; if (@num2 is null) set @num2 = 0; set @result = @num1 + @num2; return @result; end go
调用函数
select dbo.fun_add(id, age) from student;
自定义函数，字符串连接
if (object_id(‘fun_append‘, ‘fn‘) is not null) drop function fun_append go create function fun_append(@args nvarchar(1024), @args2 nvarchar(1024)) returns nvarchar(2048) as begin return @args + @args2; end go select dbo.fun_append(name, ‘abc‘) from student;
修改函数
alter function fun_append(@args nvarchar(1024), @args2 nvarchar(1024)) returns nvarchar(1024) as begin declare @result varchar(1024); --coalesce返回第一个不为null的值 set @args = coalesce(@args, ‘‘); set @args2 = coalesce(@args2, ‘‘);; set @result = @args + @args2; return @result; end go select dbo.fun_append(name, ‘#abc‘) from student;
返回table类型函数
--返回table对象函数 select name, object_id, type from sys.objects where type in (‘fn‘, ‘if‘, ‘tf‘) or type like ‘%f%‘; if (exists (select * from sys.objects where type in (‘fn‘, ‘if‘, ‘tf‘) and name = ‘fun_find_stuRecord‘)) drop function fun_find_stuRecord go create function fun_find_stuRecord(@id int) returns table as return (select * from student where id = @id); go select * from dbo.fun_find_stuRecord(2);
原文：http://www.cnblogs.com/gyt-xtt/p/5834199.html