Ø 基本常用查詢 --select select * from student; --all 查詢所有 select all sex from student; --distinct 過濾重復 select distinct sex from student; --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; --alias column name 列重命名 select id as 編號, name '名稱', sex 性別 from student; --alias table name 表重命名 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 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 ... 相當于并且 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 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(tǒng)計 select count(age), age from student group by age; 按照性別進行分組統(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的數據，并完成運算后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，過濾年齡為空的數據，并且統(tǒng)計分組的條數和現(xiàn)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大于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于等于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; Ø 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。 # from (select … table)示例 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(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 # 示例 查詢班級信息，統(tǒng)計班級學生人生 select *, (select count(*) from student where cid = classes.id) as num from classes order by num; # in, not in子句查詢示例 查詢班級id大于小于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 ); 查詢不是班的學生信息 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果必須是一列，這一列的結果將會作為查詢條件對應前面的條件。如cid對應子句的id； # exists和not exists子句查詢示例 查詢存在班級id為的學生信息 select * from student where exists ( select * from classes where id = student.cid and id = 3 ); 查詢沒有分配班級的學生信息 select * from student where not exists ( select * from classes where id = student.cid ); exists和not exists查詢需要內部查詢和外部查詢進行一個關聯(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； # some、any、all子句查詢示例 查詢班級的學生年齡大于班級的學生的年齡的信息 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 ); Ø 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 對年齡大于的進行匯總 select age from student where age > 20 order by age compute sum(age) by age; 對年齡大于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(zhí)行聚合函數的列 compute by適合做先分組后匯總的業(yè)務。compute by后面的列一定要是order by中出現(xiàn)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 Ø 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并且給出序號。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 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(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; # rank函數函數 根據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; 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; # dense_rank函數 根據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; # 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(lián)合使用。 利用partition by按照班級名稱分組，學生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; Ø 集合運算 操作兩組查詢結果，進行交集、并集、減集運算 1、 union和union all進行并集運算 --union 并集、不重復 select id, name from student where name like 'ja%' union select id, name from student where id = 4; --并集、重復 select * from student where name like 'ja%' union all select * from student; 2、 intersect進行交集運算 --交集（相同部分） select * from student where name like 'ja%' intersect select * from student; 3、 except進行減集運算 --減集（除相同部分） select * from student where name like 'ja%' except select * from student where name like 'jas%'; Ø 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，不利于理解。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(zhí)行范圍內進行定義。 --表達式 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; Ø 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; 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; 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; 4、 inner join內連接 --內連接 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交叉連接 --交叉聯(lián)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 cross join classes c --where s.cid = c.id; 6、 自連接（同一張表進行連接查詢） --自連接 select distinct s.* from student s, student s1 where s.id > s1.id and s.sex = s1.sex; Ø 函數 1、 聚合函數 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; 2、 日期時間函數 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和時間邊界數 select dateDiff(day, '2011-06-20', getDate()); --相差秒數 select dateDiff(second, '2011-06-22 11:00:00', getDate()); --相差小時數 select dateDiff(hour, '2011-06-22 10:00:00', getDate()); select dateName(month, getDate());--當前月份 select dateName(minute, getDate());--當前分鐘 select dateName(weekday, getDate());--當前星期 select datePart(month, getDate());--當前月份 select datePart(weekday, getDate());--當前星期 select datePart(second, getDate());--當前秒數 select day(getDate());--返回當前日期天數 select day('2011-06-30');--返回當前日期天數 select month(getDate());--返回當前日期月份 select month('2011-11-10'); select year(getDate());--返回當前日期年份 select year('2010-11-10'); select getDate();--當前系統(tǒng)日期 select getUTCDate();--utc日期 3、 數學函數 select pi();--PI函數 select rand(100), rand(50), rand(), rand();--隨機數 select round(rand(), 3), round(rand(100), 5);--精確小數位 --精確位數，負數表示小數點前 select round(123.456, 2), round(254.124, -2); select round(123.4567, 1, 2); 4、 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'); 5、 字符串函數 select ascii('a');--字符轉換ascii值 select ascii('A'); select char(97);--ascii值轉換字符 select char(65); select nchar(65); select nchar(45231); select nchar(32993);--unicode轉換字符 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'); 6、 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); 7、 系統(tǒng)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_timest--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 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 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; 8、 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 9、 系統(tǒng)統(tǒng)計函數 select @@CONNECTIONS;--連接數 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 select @@PACKET_ERRORS;--發(fā)生的網絡數據包錯誤數 select @@TOTAL_WRITE;--sqlserver執(zhí)行的磁盤寫入次數 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 # 查看當前數據庫所有函數 --查詢所有已創(chuàng)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(chuàng)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類型函數 --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);
