SQL Server T-SQL高級查詢
高級查詢在數(shù)據(jù)庫中用得是最頻繁的,也是應(yīng)用最廣泛的。
? 基本常用查詢
--
select
select * from student;
?
--
all
查詢所有
select all sex from student;
?
--
distinct
過濾重復(fù)
select distinct sex from student;
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--
count
統(tǒng)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;
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-- alias column name 列重命名
select id as 編號, name '名稱' , sex 性別 from student;
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-- alias table name 表重命名
select id, name, s.id, s.name from student s;
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--
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;
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--
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
并且
select * from student where id > 2 and sex = 1;
?
--
or
或者
select * from student where id = 2 or sex = 1;
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-- between ... and ... 相當(dāng)于并且
select * from student where id between 2 and 5;
select * from student where id not between 2 and 5;
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--
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]%' ;
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--
in
子查詢
select * from student where id in (1, 2);
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-- not in 不在其中
select * from student where id not in (1, 2);
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-- is null 是空
select * from student where age is null ;
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-- is not null 不為空
select * from student where age is not null ;
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-- order by 排序
select * from student order by name;
select * from student order by name desc ;
select * from student order by name asc ;
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-- group by 分組
按照年齡進(jìn)行分組統(tǒng)計
select count (age), age from student group by age;
按照性別進(jìn)行分組統(tǒng)計
select count (*), sex from student group by sex;
按照年齡和性別組合分組統(tǒng)計,并排序
select count (*), sex from student group by sex, age order by age;
按照性別分組,并且是id大于2的記錄最后按照性別排序
select count (*), sex from student where id > 2 group by sex order by sex;
查詢id大于2的數(shù)據(jù),并完成運算后的結(jié)果進(jìn)行分組和排序
select count (*), (sex * id) new from student where id > 2 group by sex * id order by sex * id;
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-- 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;
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--
having
分組過濾條件
按照年齡分組,過濾年齡為空的數(shù)據(jù),并且統(tǒng)計分組的條數(shù)和現(xiàn)實年齡信息
select count (*), age from student group by age having age is not null ;
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按照年齡和cid組合分組,過濾條件是cid大于1的記錄
select count (*), cid, sex from student group by cid, sex having cid > 1;
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按照年齡分組,過濾條件是分組后的記錄條數(shù)大于等于2
select count (*), age from student group by age having count (age) >= 2;
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按照cid和性別組合分組,過濾條件是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(dá)式的地方都可以使用子查詢。子查詢也稱為內(nèi)部查詢或內(nèi)部選擇,而包含子查詢的語句也成為外部查詢或外部選擇。
?
# from (select … table)示例
將一個table的查詢結(jié)果當(dāng)做一個新表進(jìn)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(nèi)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(guī)選擇列表組件的常規(guī)select查詢
???? 2、 包含一個或多個表或視圖名稱的常規(guī)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
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# 示例
查詢班級信息,統(tǒng)計班級學(xué)生人生
select *, ( select count (*) from student where cid = classes.id) as num
from classes order by num;
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# in, not in子句查詢示例
查詢班級id大于小于的這些班級的學(xué)生信息
select * from student where cid in (
select id from classes where id > 2 and id < 4
);
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查詢不是班的學(xué)生信息
select * from student where cid not in (
select id from classes where name = '2班'
)
in、not in 后面的子句返回的結(jié)果必須是一列,這一列的結(jié)果將會作為查詢條件對應(yīng)前面的條件。如cid對應(yīng)子句的id;
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# exists和not exists子句查詢示例
查詢存在班級id為的學(xué)生信息
select * from student where exists (
select * from classes where id = student.cid and id = 3
);
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查詢沒有分配班級的學(xué)生信息
select * from student where not exists (
select * from classes where id = student.cid
);
exists和not exists查詢需要內(nèi)部查詢和外部查詢進(jìn)行一個關(guān)聯(lián)的條件,如果沒有這個條件將是查詢到的所有信息。如:id等于student.id;
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# some、any、all子句查詢示例
查詢班級的學(xué)生年齡大于班級的學(xué)生的年齡的信息
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
);
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? 聚合查詢
1、 distinct去掉重復(fù)數(shù)據(jù)
select distinct sex from student;
select count (sex), count ( distinct sex) from student;
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2、 compute和compute by匯總查詢
對年齡大于的進(jìn)行匯總
select age from student
where age > 20 order by age compute sum (age) by age;
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對年齡大于的按照性別進(jìn)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);
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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(jìn)行匯總前面是查詢的結(jié)果,后面一條結(jié)果集就是匯總的信息。compute子句中可以添加多個匯總表達(dá)式,可以添加的信息如下:
???? a、 可選by關(guān)鍵字。它是每一列計算指定的行聚合
???? b、 行聚合函數(shù)名稱。包括sum、avg、min、max、count等
???? c、 要對其執(zhí)行聚合函數(shù)的列
???? compute by適合做先分組后匯總的業(yè)務(wù)。compute by后面的列一定要是order by中出現(xiàn)的列。
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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(jié)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(jié)合group by語句完成分組匯總
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? 排序函數(shù)
?? 排序在很多地方需要用到,需要對查詢結(jié)果進(jìn)行排序并且給出序號。比如:
?? 1、 對某張表進(jìn)行排序,序號需要遞增不重復(fù)的
?? 2、 對學(xué)生的成績進(jìn)行排序,得出名次,名次可以并列,但名次的序號是連續(xù)遞增的
?? 3、 在某些排序的情況下,需要跳空序號,雖然是并列
基本語法
排序函數(shù) 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
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# row_number函數(shù)
根據(jù)排序子句給出遞增連續(xù)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;
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# rank函數(shù)函數(shù)
根據(jù)排序子句給出遞增的序號,但是存在并列并且跳空
順序遞增
select id, name, rank() over ( order by cid) as rank from student;
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跳過相同遞增
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;
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# dense_rank函數(shù)
根據(jù)排序子句給出遞增的序號,但是存在并列不跳空
不跳過,直接遞增
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;
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# partition by分組子句
可以完成對分組的數(shù)據(jù)進(jìn)行增加排序,partition by可以與以上三個函數(shù)聯(lián)合使用。
利用partition by按照班級名稱分組,學(xué)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;
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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;
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# ntile平均排序函數(shù)
將要排序的數(shù)據(jù)進(jìn)行平分,然后按照等分排序。ntile中的參數(shù)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;
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? 集合運算
操作兩組查詢結(jié)果,進(jìn)行交集、并集、減集運算
1、 union和union all進(jìn)行并集運算
--
union
并集、不重復(fù)
select id, name from student where name like 'ja%'
union
select id, name from student where id = 4;
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--并集、重復(fù)
select * from student where name like 'ja%'
union all
select * from student;
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2、 intersect進(jìn)行交集運算
--交集(相同部分)
select * from student where name like 'ja%'
intersect
select * from student;
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3、 except進(jìn)行減集運算
--減集(除相同部分)
select * from student where name like 'ja%'
except
select * from student where name like 'jas%' ;
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? 公式表表達(dá)式
查詢表的時候,有時候中間表需要重復(fù)使用,這些子查詢被重復(fù)查詢調(diào)用,不但效率低,而且可讀性低,不利于理解。那么公式表表達(dá)式可以解決這個問題。
我們可以將公式表表達(dá)式(CET)視為臨時結(jié)果集,在select、insert、update、delete或是create view語句的執(zhí)行范圍內(nèi)進(jìn)行定義。
--表達(dá)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;
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with statNum(id, num) as
(
select cid, count (*)
from
student
where
id > 0
group by cid
)
select max (id), avg (num) from statNum;
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? 連接查詢
1、 簡化連接查詢
--簡化聯(lián)接查詢
select s.id, s.name, c.id, c.name from student s, classes c where s.cid = c.id;
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2、 left join左連接
--左連接
select s.id, s.name, c.id, c.name from student s left join classes c on s.cid = c.id;
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3、 right join右連接
--右連接
select s.id, s.name, c.id, c.name from student s right join classes c on s.cid = c.id;
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4、 inner join內(nèi)連接
--內(nèi)連接
select s.id, s.name, c.id, c.name from student s inner join classes c on s.cid = c.id;
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--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;
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5、 cross join交叉連接
--交叉聯(lián)接查詢,結(jié)果是一個笛卡兒乘積
select s.id, s.name, c.id, c.name from student s cross join classes c
--
where
s.cid = c.id;
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6、 自連接(同一張表進(jìn)行連接查詢)
--自連接
select distinct s.* from student s, student s1 where s.id <> s1.id and s.sex = s1.sex;
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? 函數(shù)
1、 聚合函數(shù)
max最大值、min最小值、count統(tǒng)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;
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2、 日期時間函數(shù)
select dateAdd( day , 3, getDate());--加天
select dateAdd( year , 3, getDate());--加年
select dateAdd( hour , 3, getDate());--加小時
--返回跨兩個指定日期的日期邊界數(shù)和時間邊界數(shù)
select dateDiff( day , '2011-06-20' , getDate());
--相差秒數(shù)
select dateDiff( second , '2011-06-22 11:00:00' , getDate());
--相差小時數(shù)
select dateDiff( hour , '2011-06-22 10:00:00' , getDate());
select dateName( month , getDate());--當(dāng)前月份
select dateName( minute , getDate());--當(dāng)前分鐘
select
dateName(weekday, getDate());--當(dāng)前星期
select datePart( month , getDate());--當(dāng)前月份
select
datePart(weekday, getDate());--當(dāng)前星期
select datePart( second , getDate());--當(dāng)前秒數(shù)
select day (getDate());--返回當(dāng)前日期天數(shù)
select day ( '2011-06-30' );--返回當(dāng)前日期天數(shù)
select month (getDate());--返回當(dāng)前日期月份
select month ( '2011-11-10' );
select year (getDate());--返回當(dāng)前日期年份
select year ( '2010-11-10' );
select
getDate();--當(dāng)前系統(tǒng)日期
select
getUTCDate();--utc日期
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3、 數(shù)學(xué)函數(shù)
select
pi();--PI函數(shù)
select
rand(100), rand(50), rand(), rand();--隨機數(shù)
select
round(rand(), 3), round(rand(100), 5);--精確小數(shù)位
--精確位數(shù),負(fù)數(shù)表示小數(shù)點前
select
round(123.456, 2), round(254.124, -2);
select
round(123.4567, 1, 2);
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4、 元數(shù)據(jù)
select col_name(object_id( 'student' ), 1);--返回列名
select col_name(object_id( 'student' ), 2);
--該列數(shù)據(jù)類型長度
select col_length( 'student' , col_name(object_id( 'student' ), 2));
--該列數(shù)據(jù)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' );
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5、 字符串函數(shù)
select ascii( 'a' );--字符轉(zhuǎn)換ascii值
select ascii( 'A' );
select char (97);--ascii值轉(zhuǎn)換字符
select char (65);
select nchar (65);
select nchar (45231);
select nchar (32993);--unicode轉(zhuǎn)換字符
select unicode( 'A' ), unicode( '中' );--返回unicode編碼值
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' ;--輸出空格
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' );
--精確數(shù)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' );--比較字符串相同
select difference( 'hello' , 'world' );
select difference( 'hello' , 'llo' );
select difference( 'hello' , 'hel' );
select difference( 'hello' , 'hello' );
select replace( 'abcedef' , 'e' , 'E' );--替換字符串
select stuff( 'hello world' , 3, 4, 'ABC' );--指定位置替換字符串
select replicate( 'abc#' , 3);--重復(fù)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' );--返回長度
select reverse( 'sqlServer' );--反轉(zhuǎn)字符串
?
select left ( 'leftString' , 4);--取左邊字符串
select left ( 'leftString' , 7);
select right ( 'leftString' , 6);--取右邊字符串
select right ( 'leftString' , 3);
select lower ( 'aBc' ), lower ( 'ABC' );--小寫
select upper ( 'aBc' ), upper ( 'abc' );--大寫
--去掉左邊空格
select ltrim( ' abc' ), ltrim( '# abc#' ), ltrim( ' abc' );
--去掉右邊空格
select rtrim( ' abc ' ), rtrim( '# abc# ' ), rtrim( 'abc' );
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6、 安全函數(shù)
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);
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7、 系統(tǒng)函數(shù)
select
app_name();--當(dāng)前會話的應(yīng)用程序名稱
select cast (2011 as datetime), cast ( '10' as money), cast ( '0' as varbinary);--類型轉(zhuǎn)換
select convert (datetime, '2011' );--類型轉(zhuǎn)換
select coalesce ( null , 'a' ), coalesce ( '123' , 'a' );--返回其參數(shù)中第一個非空表達(dá)式
select collationProperty( 'Traditional_Spanish_CS_AS_KS_WS' , 'CodePage' );
select current_timestamp ;--當(dāng)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 identity ( int , 1, 1) as id into tab from student;--將studeng表的烈屬,以/1自增形式創(chuàng)建一個tab
select * from tab;
select @@ rowcount ;--影響行數(shù)
select
@@cursor_rows;--返回連接上打開的游標(biāo)的當(dāng)前限定行的數(shù)目
select
@@error;--T-SQL的錯誤號
select
@@procid;
?
8、 配置函數(shù)
set
datefirst 7;--設(shè)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(dāng)前數(shù)據(jù)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(dāng)前語言名稱
select
@@lock_timeout;--返回當(dāng)前會話的當(dāng)前鎖定超時設(shè)置(毫秒)
select
@@max_connections;--返回SQL Server 實例允許同時進(jìn)行的最大用戶連接數(shù)
select @@MAX_PRECISION AS 'Max Precision' ;--返回decimal 和numeric 數(shù)據(jù)類型所用的精度級別
select @@SERVERNAME;-- SQL Server 的本地服務(wù)器的名稱
select
@@SERVICENAME;--服務(wù)名
select
@@SPID;--當(dāng)前會話進(jìn)程id
select @@ textSize ;
select
@@version;--當(dāng)前數(shù)據(jù)庫版本信息
?
9、 系統(tǒng)統(tǒng)計函數(shù)
select
@@CONNECTIONS;--連接數(shù)
select
@@PACK_RECEIVED;
select
@@CPU_BUSY;
select
@@PACK_SENT;
select
@@TIMETICKS;
select
@@IDLE;
select
@@TOTAL_ERRORS;
select
@@IO_BUSY;
select
@@TOTAL_READ;--讀取磁盤次數(shù)
select
@@PACKET_ERRORS;--發(fā)生的網(wǎng)絡(luò)數(shù)據(jù)包錯誤數(shù)
select
@@TOTAL_WRITE;--sqlserver執(zhí)行的磁盤寫入次數(shù)
select patIndex( '%soft%' , 'microsoft SqlServer' );
select patIndex( 'soft%' , 'software SqlServer' );
select patIndex( '%soft' , 'SqlServer microsoft' );
select patIndex( '%so_gr%' , 'Jsonisprogram' );
?
10、 用戶自定義函數(shù)
# 查看當(dāng)前數(shù)據(jù)庫所有函數(shù)
--查詢所有已創(chuàng)建函數(shù)
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(chuàng)建函數(shù)
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(diào)用函數(shù)
select dbo.fun_add(id, age) from student;
?
--自定義函數(shù),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(shù)
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類型函數(shù)
--返回table對象函數(shù)
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);
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