【SQL】高級函數匯總

基本常用查詢

-- all 查詢所有,幾乎從來不用 all 關鍵字,因為是默認關鍵字
select all sex from student;
 
-- distinct 過濾重復 (常用語檢查一列數據是否有異常值)
select distinct sex from student;
 
-- count 統計
select count(distinct sex) from student;
 
-- top 取前N條記錄
select top 3 * from student;
 
-- 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;
 
-- having 分組過濾條件
-- 按照年齡分組，過濾年齡為空的數據，並且統計分組的條數和現實年齡信息
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;
 
-- 按照年齡分組，過濾條件是分組后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;

嵌套子查詢

    子查詢是一個嵌套在select、insert、update 或 delete 語句或其他子查詢中的查詢。任何允許使用表達式的地方都可以使用子查詢。子查詢也稱為內部查詢或內部選擇，而包含子查詢的語句也成為外部查詢或外部選擇。

-- 將一個 table 的查詢結果當做一個新表進行查詢
select * from (
    select id, name from student where sex = 1
) t where t.id > 2;

上面括號中的語句，就是子查詢語句（內部查詢）。在外面的是外部查詢，其中外部查詢可以包含以下語句：

     1、 包含常規選擇列表組件的常規select查詢

     2、 包含一個或多個表或視圖名稱的常規from語句

     3、 可選的where子句

     4、 可選的group by子句

     5、 可選的having子句

-- 查詢班級信息，統計班級學生人生
select *, (select count(*) from student where cid = classes.id) as num 
from classes order by num;
 
-- 查詢班級id大於小於X的這些班級的學生信息
select * from student where cid in (
    select id from classes where id > 2 and id < 4
);
 
-- 查詢不是X班的學生信息
select * from student where cid not in (
    select id from classes where name = '2班'
)
 
-- all,any,some
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
);

聚合查詢

1、 distinct去掉重復數據

select distinct sex from student;
select count(sex), count(distinct sex) from student;

2、 compute和compute by匯總查詢

-- 對年齡大於20的進行匯總
select age from student where age > 20 order by age compute sum(age) by age;
 
-- 對年齡大於20的按照性別進行分組匯總年齡信息
select id, sex, age from student where age > 20 order by sex, age compute sum(age) by sex;
 
-- 按照年齡分組匯總
select age from student where age > 20 order by age, id compute sum(age);
 
-- 按照年齡分組，年齡匯總，id找最大值
select id, age from student where age > 20 order by age compute sum(age), max(id);

compute 進行匯總，前面是查詢的結果，后面一條結果集就是匯總的信息。compute 子句中可以添加多個匯總表達式，可以添加的信息如下：

     a、 可選by關鍵字。它是每一列計算指定的行聚合

     b、 行聚合函數名稱。包括sum、avg、min、max、count等

     c、 要對其執行聚合函數的列

     compute by適合做先分組后匯總的業務。compute by 后面的列一定要是 order by 中出現的列。

3、 cube 匯總

cube匯總和compute效果類似，但語法較簡潔，而且返回的是一個結果集。

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要結合group by語句完成分組匯總

排序函數

   排序在很多地方需要用到，需要對查詢結果進行排序並且給出序號。比如：

   1、 對某張表進行排序，序號需要遞增不重復的

   2、 對學生的成績進行排序，得出名次，名次可以並列，但名次的序號是連續遞增的

   3、 在某些排序的情況下，需要跳空序號，雖然是並列

-- 基本語法 
-- 排序函數 over([分組語句] 排序子句[desc][asc])
-- 排序子句 order by 列名, 列名
-- 分組子句 partition by 分組列, 分組列
 
 
-- row_number 函數
-- 根據排序子句給出遞增連續序號,按照名稱排序的順序遞增
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 函數函數 
-- 根據排序子句給出遞增的序號，但是存在並列並且跳空 
-- 順序遞增
select id, name, rank() over(order by cid) as rank from student;
 
-- dense_rank 函數 
-- 根據排序子句給出遞增的序號，但是存在並列不跳空 
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 分組子句 
-- 可以完成對分組的數據進行增加排序，partition by可以與以上三個函數聯合使用。 
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 平均排序函數 
-- 將要排序的數據進行平分，然后按照等分排序。ntile中的參數代表分成多少等分。 
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;

集合運算

操作兩組查詢結果，進行交集、並集、減集運算

-- union 並集、不重復
select id, name from student where name like 'ja%'
union select id, name from student where id = 4;
 
-- union all 並集、重復
select * from student where name like 'ja%'
union all select * from student;
 
-- 交集（相同部分）
select * from student where name like 'ja%'
intersect select * from student;
 
-- 減集（除相同部分）
select * from student where name like 'ja%'
except select * from student where name like 'jas%';

公式表表達式

查詢表的時候，有時候中間表需要重復使用，這些子查詢被重復查詢調用，不但效率低，而且可讀性低，不利於理解。那么公式表表達式可以解決這個問題。

我們可以將公式表表達式（CET）視為臨時結果集，在select、insert、update、delete或是create view語句的執行范圍內進行定義。

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;

表的聯合查詢

-- 簡化聯接查詢
select s.id, s.name, c.id, c.name from student s, classes c where s.cid = c.id;
 
-- 左連接 (左為基表)
select s.id, s.name, c.id, c.name from student s left join classes c on s.cid = c.id;
 
-- 右連接 (右為基表)
select s.id, s.name, c.id, c.name from student s right join classes c on s.cid = c.id;
 
-- 內連接 (等值聯合)
select s.id, s.name, c.id, c.name from student s inner join classes c on s.cid = c.id;
 
-- 交叉聯接查詢，結果是一個笛卡兒乘積
select s.id, s.name, c.id, c.name from student s ,classes c
 
-- 自連接
select distinct s.* from student s, student s1 where s.id <> s1.id and s.sex = s1.sex;

函數

-- 聚合函數 (max最大值、min最小值、count統計、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;
 
-- 日期時間函數 
select dateAdd(day, 3, getDate());
select dateAdd(year, 3, getDate());
select dateAdd(hour, 3, getDate());
select dateDiff(day, '2011-06-20', getDate());
select dateDiff(second, '2011-06-22 11:00:00', getDate());
select dateDiff(hour, '2011-06-22 10:00:00', getDate());
select dateName(month, getDate());
select dateName(minute, getDate());
select dateName(weekday, getDate());
select datePart(month, getDate());
select datePart(weekday, getDate());
select datePart(second, getDate());
select day(getDate());
select day('2011-06-30');
select month(getDate());
select month('2011-11-10');
select year(getDate());
select year('2010-11-10');
select getDate();
select getUTCDate();
 
-- 數學函數 
select pi();
select rand(100), rand(50), rand();
select round(rand(), 3), round(rand(100), 5);
select round(123.456, 2), round(254.124, -2);
select round(123.4567, 1, 2);
 
-- 元數據 
select col_name(object_id('student'), 1); // 返回列名
select col_name(object_id('student'), 2);
-- 該列數據類型長度
select col_length('student', col_name(object_id('student'), 2)); 
-- 該列數據類型長度
select col_length('student', col_name(object_id('student'), 1)); 
-- 返回類型名稱、類型id
select type_name(type_id('varchar')), type_id('varchar');
-- 返回列類型長度
select columnProperty(object_id('student'), 'name', 'PRECISION');
-- 返回列所在索引位置
select columnProperty(object_id('student'), 'sex', 'ColumnId');
 
-- 字符串函數 
select ascii('a');
select ascii('A');
select char(97);
select char(65);
select nchar(65);
select nchar(45231);
select nchar(32993);
select unicode('A'), unicode('中');
select soundex('hello'), soundex('world'), soundex('word');
select patindex('%a', 'ta'), patindex('%ac%', 'jack'), patindex('dex%', 'dexjack');
select 'a' + space(2) + 'b', 'c' + space(5) + 'd';
select charIndex('o', 'hello world');
select charIndex('o', 'hello world', 6);
select quoteName('abc[]def'), quoteName('123]45');
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');
select difference('hello', 'world');
select difference('hello', 'llo');
select difference('hello', 'hel');
select difference('hello', 'hello');
select replace('abcedef', 'e', 'E');
select stuff('hello world', 3, 4, 'ABC');
select replicate('abc#', 3);
select subString('abc', 1, 1), subString('abc', 1, 2), subString('hello Wrold', 7, 5);
select len('abc');
select reverse('sqlServer'); 
select left('leftString', 4);
select left('leftString', 7);
select right('leftString', 6);
select right('leftString', 3);
select lower('aBc'), lower('ABC');
select upper('aBc'), upper('abc');
select ltrim(' abc'), ltrim('# abc#'), ltrim('  abc');
select rtrim(' abc    '), rtrim('# abc#   '), rtrim('abc');
 
-- 安全函數 
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);
 
-- 系統函數
select app_name(); // 當前會話的應用程序名稱
select cast(2011 as datetime), cast('10' as money), cast('0' as varbinary); // 類型轉換
select convert(datetime, '2011'); // 類型轉換
select coalesce(null, 'a'), coalesce('123', 'a'); // 返回其參數中第一個非空表達式
select collationProperty('Traditional_Spanish_CS_AS_KS_WS', 'CodePage');
select current_timestamp; // 當前時間戳
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'); // 返回主鍵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 @@rowcount; // 影響行數
select @@cursor_rows; // 返回連接上打開的游標的當前限定行的數目
select @@error; // T-SQL的錯誤號
select @@procid;
 
-- 配置函數 
set datefirst 7; // 設置每周的第一天，表示周日
select @@datefirst as '星期的第一天', datepart(dw, getDate()) AS '今天是星期';
select @@dbts; // 返回當前數據庫唯一時間戳
set language 'Italian';
select @@langId as 'Language ID'; // 返回語言id
select @@language as 'Language Name';// 返回當前語言名稱
select @@lock_timeout; // 返回當前會話的當前鎖定超時設置（毫秒）
select @@max_connections; // 返回SQL Server 實例允許同時進行的最大用戶連接數
select @@MAX_PRECISION AS 'Max Precision'; // 返回decimal 和numeric 數據類型所用的精度級別
select @@SERVERNAME; // SQL Server 的本地服務器的名稱
select @@SERVICENAME; // 服務名
select @@SPID; // 當前會話進程id
select @@textSize;
select @@version; // 當前數據庫版本信息
 
-- 系統統計函數 
select @@CONNECTIONS;
select @@PACK_RECEIVED;
select @@CPU_BUSY;
select @@PACK_SENT;
select @@TIMETICKS;
select @@IDLE;
select @@TOTAL_ERRORS;
select @@IO_BUSY;
select @@TOTAL_READ;
select @@PACKET_ERRORS;
select @@TOTAL_WRITE;
select patIndex('%soft%', 'microsoft SqlServer');
select patIndex('soft%', 'software SqlServer');
select patIndex('%soft', 'SqlServer microsoft');
select patIndex('%so_gr%', 'Jsonisprogram');
 
-- 查詢所有已創建函數
select definition,* from sys.sql_modules m join sys.objects o on m.object_id = o.object_id
and type in('fn', 'if', 'tf');
 
-- 創建函數
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
-- 調用函數
select dbo.fun_add(id, age) from student;
 
-- 自定義函數，字符串連接
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;
 
-- 修改函數
alter function fun_append(@args nvarchar(1024), @args2 nvarchar(1024))
    returns nvarchar(1024)
as
    begin
        declare @result varchar(1024);    
        -- coalesce返回第一個不為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對象函數
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);

 

 

轉自大神：https://blog.csdn.net/wang1127248268/article/details/53406564