《Mysql入門日常收集整理常見的mysql sql技巧》要點(diǎn)：
本文介紹了Mysql入門日常收集整理常見的mysql sql技巧，希望對(duì)您有用。如果有疑問，可以聯(lián)系我們。

MYSQL入門廢話不多說了,直接給大家貼代碼了.

MYSQL入門1,數(shù)字輔助表

MYSQL入門
//創(chuàng)建表
create table test(id int unsigned not null primary key);
delimiter //
create procedure pnum(cnt int unsigned)
begin
declare i int unsigned default 1;
insert into num select i;
while i*2 < cnt do
insert into num select i+id from num ;
set i=i*2;
end while;
end
//
delimiter ;
#####列值不連續(xù)問題：
表a中id值為1,2,3,100,101,110,111
set @q=0;
select id,@q:=@q+1 as cn from a;
#####對(duì)不連續(xù)的進(jìn)行分組
set @a=0;
select min(id) as start_v,max(id) as end_v from (
select id,cn,id-cn as diff from (
select id,@a:=@a+1 as cn from pi) as p ) as pp group by diff;
#####對(duì)不連續(xù)的值填充
use test;
DROP TABLE if EXISTS pincer;
create table pincer(a int UNSIGNED);
insert into pincer values(1),(2),(5),(100),(101),(103),(104),(105);
select a+1 as start ,(select min(a)-1 from pincer as ww where ww.a>qq.a) as end from pincer as qq where 
not exists (select * from pincer as pp where qq.a+1=pp.a)
and a<(select max(a) from pincer);
################
select id,num,ranknum,diff from (select id,num,ranknum,num-ranknum as diff from (select id,num,if(@id=id,@rownum:=@rownum+1,@rownum:=1) ranknum,@id:=id from tt,(select @rownum:=0,@id:=null) a ) b) c group by id,diff having count(*)>=2;
################

MYSQL入門2,生日問題

MYSQL入門
select name,birthday,if(cur>today,cur,next) as birth_day
from(
select name,birthday,today,date_add(cur,interval if(day(birthday)=29 && day(cur)=28,1,0) day)as cur, date_ad(next,interval if(day(birthday)=29 && day(next)=28,1,0) day) as next
from(
select name,birthday,today,
  date_add(birthday,interval diff year) as cur,
  date_add(birthday,interval diff+1 year) as next,
from(
select concat(laster_name,'',first_name) as name,
  birth_date as birthday,
  (year(now())-year(birth_date) )as diff,
  now() as today
  from employees) as a
) as b
) as c

MYSQL入門3,日期問題----計(jì)算工作日

MYSQL入門
create table sals(id int ,date datetime ,cost int,primary key(id);
select date_add('1900-01-01',
            interval floor(datediff(date,'1900-01-01')/7)*7 day)
            as week_start,
            date_add('1900-01-01',
            interval floor(datediff(date,'1900-01-01')/7*7+6 day)
            as week_end,
            sum(cost) from sales;
計(jì)算工作日(指定2個(gè)日期段 有多少工作日)
create procedure pgetworkdays (s datetime,e datetime)
begin
select floor(days/7)*5+days%7
case when 6 between wd and wd+days%7-1 then 1 else 0 end
case then 7 between wd and wd+days%7-1 then 1 else 0 end
from 
(select datediff(e,s)+1 as days,weekday(s)+1 as wd) as a;
end;

MYSQL入門mysql sql語句大全

MYSQL入門1、說明：創(chuàng)建數(shù)據(jù)庫
CREATE DATABASE database-name

MYSQL入門2、說明：刪除數(shù)據(jù)庫

MYSQL入門drop database dbname

MYSQL入門3、說明：備份sql server
--- 創(chuàng)建 備份數(shù)據(jù)的 device
USE master
EXEC sp_addumpdevice 'disk', 'testBack', 'c:\mssql7backup\MyNwind_1.dat'
--- 開始 備份
BACKUP DATABASE pubs TO testBack

MYSQL入門4、說明：創(chuàng)建新表

MYSQL入門create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)
根據(jù)已有的表創(chuàng)建新表：
A：create table tab_new like tab_old (使用舊表創(chuàng)建新表)
B：create table tab_new as select col1,col2… from tab_old definition only

MYSQL入門5、說明：刪除新表

MYSQL入門drop table tabname

MYSQL入門6、說明：增加一個(gè)列
Alter table tabname add column col type
注：列增加后將不能刪除.DB2中列加上后數(shù)據(jù)類型也不能改變,唯一能改變的是增加varchar類型的長度.

MYSQL入門7、說明：添加主鍵： Alter table tabname add primary key(col)
說明：刪除主鍵： Alter table tabname drop primary key(col)

MYSQL入門8、說明：創(chuàng)建索引：create [unique] index idxname on tabname(col….)

MYSQL入門刪除索引：drop index idxname

MYSQL入門注：索引是不可更改的,想更改必須刪除重新建.

MYSQL入門9、說明：創(chuàng)建視圖：create view viewname as select statement

MYSQL入門刪除視圖：drop view viewname

MYSQL入門10、說明：幾個(gè)簡單的基本的sql語句
選擇：select * from table1 where 范圍
插入：insert into table1(field1,field2) values(value1,value2)
刪除：delete from table1 where 范圍
更新：update table1 set field1=value1 where 范圍
查找：select * from table1 where field1 like '%value1%' ---like的語法很精妙,查資料!
排序：select * from table1 order by field1,field2 [desc]
總數(shù)：select count as totalcount from table1
求和：select sum(field1) as sumvalue from table1
平均：select avg(field1) as avgvalue from table1
最大：select max(field1) as maxvalue from table1
最小：select min(field1) as minvalue from table1

MYSQL入門11、說明：幾個(gè)高級(jí)查詢運(yùn)算詞
A： UNION 運(yùn)算符
UNION 運(yùn)算符通過組合其他兩個(gè)結(jié)果表(例如 TABLE1 和 TABLE2)并消去表中任何重復(fù)行而派生出一個(gè)結(jié)果表.當(dāng) ALL 隨 UNION 一起使用時(shí)(即 UNION ALL),不消除重復(fù)行.兩種情況下,派生表的每一行不是來自 TABLE1 就是來自 TABLE2.
B： EXCEPT 運(yùn)算符
EXCEPT 運(yùn)算符通過包括所有在 TABLE1 中但不在 TABLE2 中的行并消除所有重復(fù)行而派生出一個(gè)結(jié)果表.當(dāng) ALL 隨 EXCEPT 一起使用時(shí) (EXCEPT ALL),不消除重復(fù)行.
C： INTERSECT 運(yùn)算符
INTERSECT 運(yùn)算符通過只包括 TABLE1 和 TABLE2 中都有的行并消除所有重復(fù)行而派生出一個(gè)結(jié)果表.當(dāng) ALL 隨 INTERSECT 一起使用時(shí) (INTERSECT ALL),不消除重復(fù)行.
注：使用運(yùn)算詞的幾個(gè)查詢結(jié)果行必須是一致的.

MYSQL入門12、說明：使用外連接

MYSQL入門A、left (outer) join：
左外連接(左連接)：結(jié)果集幾包括連接表的匹配行,也包括左連接表的所有行.
SQL: select a.a, a.b, a.c, b.c, b.d, b.f from a LEFT OUT JOIN b ON a.a = b.c
B：right (outer) join:
右外連接(右連接)：結(jié)果集既包括連接表的匹配連接行,也包括右連接表的所有行.
C：full/cross (outer) join：
全外連接：不僅包括符號(hào)連接表的匹配行,還包括兩個(gè)連接表中的所有記錄.
12、分組:Group by:
? 一張表,一旦分組完成后,查詢后只能得到組相關(guān)的信息.
?組相關(guān)的信息：(統(tǒng)計(jì)信息) count,sum,max,min,avg? 分組的標(biāo)準(zhǔn))
??? 在SQLServer中分組時(shí)：不能以text,ntext,image類型的字段作為分組依據(jù)
?在selecte統(tǒng)計(jì)函數(shù)中的字段,不能和普通的字段放在一起；

MYSQL入門13、對(duì)數(shù)據(jù)庫進(jìn)行操作：

MYSQL入門分離數(shù)據(jù)庫： sp_detach_db; 附加數(shù)據(jù)庫：sp_attach_db 后接表明,附加需要完整的路徑名

MYSQL入門14.如何修改數(shù)據(jù)庫的名稱:

MYSQL入門sp_renamedb 'old_name', 'new_name'

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