MySQL一些常用高级SQL语句

use kgc;
create table location (Region char(20),store_name char(20));
insert into location values ('East','Boston') ;
insert into location values ('East','New York');
insert into location values ('west','Los Angeles');
insert into location values ('west','Houston') ;

create table Store_Info (Store_Name char(20),sales int(10),Date char(10));
insert into Store_Info values ('Los Angeles','1500','2020-12-05');
insert into Store_Info values ('Houston','250','2020-12-07');
insert into Store_Info values ('Los Angeles','300','2020-12-08');
insert into Store_Info values ('Boston','700','2020-12-08');

---- SELECT ---- 显示表格中一个或数个栏位的所有资料
语法: SELECT "栏位" FROM "表名";
SELECT Store_Name FROM Store_Info;

---- DISTINCT ---- 不显示重复的资料
语法: SELECT DISTINCT "栏位" FROM "表名";
SELECT DISTINCT Store_Name FROM Store_Info;

---- WHERE ---- 有条件查询
语法:SELECT "栏位” FROM "表名" WHERE "条件";
SELECT Store_Name FROM Store_Info WHERE Sales > 1000;

---- AND OR ---- 且 或
语法:SELECT "栏位" FROM "表名” WHERE "条件1" {[ANDIOR] "条件2"}+;
SELECT Store_Name FROM Store_Info WHERE Sales > 1000 OR (Sales < 500 AND Sales > 200);

---- IN ---- 显示己知的值的资料
语法: SELECT "栏位" FROM "表名" WHERE "栏位" IN ('值1','值2', ...);
SELECT * FROM Store_Info WHERE Store_Name IN ('Los Angeles','Houston');

---- BETWEEN ---- 显示两个值范围内的资料
语法:SELECT "栏位" FROM "表名" WHERE "栏位" BETWEEN '值1' AND '值2';
SELECT * FROM Store_Info WHERE Date BETWEEN '2020-12-06' AND '2020-12-10';

---- 通配符 ---- 通常通配符都是跟LIKE一起使用的
% : 百分号表示零个、一个或多个字符
_ : 下划线表示单个字符

'A_Z':所有以‘A'起头，另一个任何值的字符，且以Z'为结尾的字符串。例如，'A.BZ'和‘A.22'都符合这一个模式，而‘AKK2'并不符合(因为在A和Z之间有两个字符，而不是一个字符)。
'ABC%':所有以'ABC'起头的字符串。例如，'ABCD'和'ABCABC'都符合这个模式。
'%XYZ':所有以'XYZ'结尾的字符串。例如，'WXYZ'和‘ZZXYZ'都符合这个模式。
'%AN%':所有含有'AN'这个模式的字符串。例如，'LOS ANGELES'和'SAN FRANCISCO'都符合这个模式。
'_AN%':所有第二个字母为‘A'和第三个字母为'N'的字符串。例如，'SAMN FRANCITSCO'符合这个模式，而'LOS ANGELES'则不符合这个模式。
---- LIKE ---- 匹配一个模式来找出我们要的资料
语法:SELECT "栏位" FROM "表名" WHERE "栏位" LIKE {模式};
SELECT * FROM Store_Info WHERE Store_Name like '%os%';
---- ORDER BY ---- 按关键字排序
语法:SELECT "栏位" FROM "表名" [WHERE "条件"] ORDER BY "栏位" [ASC，DESC];
#ASC是按照升序进行排序的,是默认的排序方式。
#DESC是按降序方式进行排序。
SELECT Store_Name,Sales,Date FROM Store_Info ORDER BY Sales DESC;

abs(x)                #返回x的绝对值
rand()                #返回0到1的随机数
mod(x,y)              #返回x除以y以后的余数
power(x,y)            #返回x的y次方
round(x)              #返回离x最近的整数
round(x,y)            #保留x的y位小数四舍五入后的值
sqrt(x)               #返回x的平方根
truncate(x,y)         #返回数字x截断为y位小数的值
ceil(×)               #返回大于或等于x的最小整数
floor(x)              #返回小于或等于x的最大整数
greatest(x1,x2...)    #返回集合中最大的值
least(x1,x2...)       #返回集合中最小的值


SELECT abs(-1),rand(),mod(5,3),power(2,3),round(1.89);
SELECT round(1.8937,3),truncate(1.235,2),ceil(5.2),floor(2.1),least(1.89,3,6.1,2.1);

聚合函数:
avg()       #返回指定列的平均值
count()     #返回指定列中非 NULL值的个数
min()       #返回指定列的最小值
max()       #返回指定列的最大值
sum(x)      #返回指定列的所有值之和

SELECT avg(Sales) FROM Store_Info;

SELECT count(store_Name) FROM Store_Info;
SELECT count(DISTINCT store_Name) FROM Store_Info;

SELECT max(Sales) FROM Store_Info;
SELECT min(sales) FROM Store_Info;

SELECT sum(sales) FROM Store_Info;

SELECT count(DISTINCT store_Name) FROM Store_Info;
SELECT count(*) FROM Store_Info;
#count(*)包括了所有的列的行数，在统计结果的时候，不会忽略列值为NULL
#count(列名)只包括列名那一列的行数，在统计结果的时候，会忽略列值为NULL的行

字符串函数:
trim()             #返回去除指定格式的值
concat(x,y)        #将提供的参数x和y拼接成一个字符串
substr(x,y)        #获取从字符串x中的第y个位置开始的字符串，跟substring()函数作用相同
substr(x,y,z)      #获取从字符串x中的第y个位置开始长度为z的字符串
length(x)          #返回字符串x的长度
replace(x,y,z)     #将字符串z替代字符串x中的字符串y
upper(x)           #将字符串x的所有字母变成大写字母
lower(x)           #将字符串x的所有字母变成小写字母
left(x,y)          #返回字符串x的前y个字符
right(x,y)         #返回字符串x的后y个字符
repeat(x,y)        #将字符串x重复y次
space(x)           #返回x个空格
strcmp (x,y)       #比较x和y，返回的值可以为-1,0,1
reverse(x)         #将字符串x反转

SELECT concat(Region,Store_Name) FROM location WHERE Store_Name = 'Boston';

#如sql_mode开启开启了PIPES_AS_CONCAT，"||"视为字符串的连接操作符而非或运算符,和字符串的拼接函数concat相类似，这和Oracle数据库使用方法一样的
SELECT Region || ' ' || Store_Name FROM location WHERE Store_Name = 'Boston';

SELECT substr(Store_Name,3) FROM location WHERE Store_Name = 'Los Angeles';
SELECT substr(Store_Name,2,4) FROM location WHERE Store_Name = 'New York';

SELECT TRIM ([ [位置] [要移除的字符串] FROM ] 字符串);
#[位置]:的值可以为 LEADING(起头)，TRAILING(结尾)，BOTH(起头及结尾)。
#[要移除的字符串]:从字串的起头、结尾，或起头及结尾移除的字符串。缺省时为空格

SELECT TRIM(LEADING 'Ne' FROM 'New York');

SELECT Region,length(Store_Name) FROM location;

SELECT REPLACE(Region,'ast','astern')FROM location;

---- GROUP BY ----  对GROUP BY后面的栏位的查询结果进行汇总分组，通常是结合聚合函数一起使用的
GROUP BY有一个原则，就是SELECT后面的所有列中，没有使用聚合函数的列，必须出现在GROUP BY后面。

语法:SELECT "栏位1",SUM("栏位2") FROM "表名" GROUP BY "栏位1";
SELECT Store_Name,SUM(Sales) FROM Store_Info GROUP BY Store_Name ORDER BY sales desc;

---- HAVING ---- 用来过滤由GROUP BY语句返回的记录集，通常与GROUP BY语句联合使用
HAVING语句的存在弥补了wHERE关键字不能与聚合函数联合使用的不足。如果被SELECcT的只有函数栏，那就不需要GROUP BY子句。

语法:SELECT "栏位1",SUM("栏位2") FROM "表格名" GROUP BY "栏位1" HAVING (函数条件);
SELECT Store_Name,SUM(Sales) FROM Store_Info GROUP BY Store_Name HAVING SUM (Sales) > 1500;

---- 别名 ---- 栏位别名表格别名

语法:SELECT "表格别名"."栏位1” [AS] "栏位别名" FROM "表格名" [AS] "表格别名"
SELECT A.Store_Name Store，SUM(A.Sales) "Total Sales" FROM Store_Info A GROUP BY A.Store_Name;

---- 子查询 ---- 连接表格，在WHERE子句或 HAVING子句中插入另一个 SQL语句

语法: SELECT "栏位1" FROM "表格1" WHERE "栏位2" [比较运算符]       #外查询
(SELECT "栏位1" FROM "表格2" WHERE "条件");                       #内查询

可以是符号的运算符，例如 =、>、<、>=、<= ;也可以是文字的运算符，例如LIKE、IN、BETWEEN
SELECT SUM(Sales) FROM Store_Info WHERE Store_Name IN
(SELECT Store_Name FROM location WHERE Region = 'west');

SELECT SUM(A.Sales) FROM Store_Info A WHERE A.Store_Name IN
(SELECT Store_Name FROM location B WHERE B.Store_Name = A.Store_Name);

---- EXISTS ---- 用来测试内查询有没有产生任何结果，类似布尔值是否为真
#如果有的话，系统就会执行外查询中的SQL语句。若是没有的话，那整个SQL语句就不会产生任何结果。
语法: SELECT "栏位1" FROM "表格1" WHERE EXISTS (SELECT * FROM "表格2" WHERE "条件");
SELECT SUM(Sales) FROM Store_Info WHERE EXISTS (SELECT * FROM location WHERE Region = 'West');

UPDATE Store_Info SET store_name='washington'WHERE sales=300;

inner join(内连接):只返回两个表中联结字段相等的行
left join(左连接):返回包括左表中的所有记录和右表中联结字段相等的记录
right join(右连接):返回包括右表中的所有记录和左表中联结字段相等的记录

SELECT * FROM location A INNER JOIN Store_Info B on A.Store_Name = B.store_Name ;

SELECT * FROM location A RIGHT JOIN Store_Info B on A.Store_Name = B.Store_Name ;

SELECT * FROM location A,store_Info B WHERE A.Store_Name = B.Store_Name;

SELECT A.Region REGION,SUM(B.Sales) SALES FROM location A,Store_Info B
WHERE A.Store_Name = B.Store_Name GROUP BY REGION;

---- CREATE VIEW ---- 视图，可以被当作是虚拟表或存储查询。
·视图跟表格的不同是，表格中有实际储存资料，而视图是建立在表格之上的一个架构，它本身并不实际储存资料。
·临时表在用户退出或同数据库的连接断开后就自动消失了，而视图不会消失。
·视图不含有数据，只存储它的定义，它的用途一般可以简化复杂的查询。比如你要对几个表进行连接查询，而且还要进行统计排序等操作，写SQT语句会很麻烦的，用视图将几个表联结起来，然后对这个视图进行查询操作，就和对一个表查询一样，很方便。

语法:CREATE VIEW "视图表名” AS "SELECT语句";
CREATE VIEW V_REGION_SALES AS SELECT A.Region REGION, SUM(B.Sales) SALES FROM location A
INNER JOIN Store_Info B ON A.Store_Name = B.Store_Name GROUP BY REGION;

SELECT * FROM V_REGION_SALES;
DROP VIEW V_REGION_SALES;

---- UNION ---- 联集，将两个SQL语句的结果合并起来，两个SQI语句所产生的栏位需要是同样的资料种类
UNION:生成结果的资料值将没有重复，且按照字段的顺序进行排序
语法:[SELECT 语句 1] UNION [SELECT 语句2];

UNION ALL:将生成结果的资料值都列出来，无论有无重复
语法:[SELECT 语句 1] UNION ALL [SELECT 语句 2];

SELECT Store_Name FROM location UNION SELECT Store_Name FROM Store_Info;

SELECT Store_Name FROM location UNION ALL SELECT Store_Name FROM Store_Info;

----- 交集值 ---- 取两个SQL语句结果的交集
SELECT A.Store_Name FROM location A INNER JOIN Store_Info B ON A.Store_Name = B.Store_Name;
SELECT A.Store_Name FROM location A INNER JOIN Store_Info B USING(Store_Name);

#两表基中的一个表没有指定的行，而另一个表这个行有重复，并且确实有交集的时候用
SELECT A.Store_Name FROM
(SELECT Store_Name FROM location UNION ALL SELECT Store_Name FROM store_Info) A
GROUP BY A.Store_Name HAVING COUNT(*) > 1;

#取两个sQL语句结果的交集,且没有重复
SELECT A.Store_Name FRONM (SELECT B.Store_Name FROM location B INNER JOIN Store_Info C ON B.Store_Name = C.store_Name) A
GROUP BY A.Store_Name;

SELECT DISTINCT A.Store_Name FROM location A INNER JOIN Store_Info B USING(Store_Name);

SELECT DISTIMCT Store_Name FROM location WHERE (Store_Name) IN (SELECT Store_Name FROM Store_Info);

SELECT DISTINCT A.Store_Name FROM location A LEFT JOIN Store_Info B USING(Store_Name) WHERE B.Store_Name IS NOT NULL;

---- 无交集值 ---- 显示第一个sQL语句的结果，且与第二个SQL语句没有交集的结果，且没有重复
SELECT DISTINCT Store_Name FROM location WHERE (Store_Name) NOT IN (SELECT Store_Name FROM Store_Info);

SELECT DISTINCT A.Store_Name FROM location A LEFT JOIN Store_Info B USING(Store_Name) WHERE B.Store_Name IS NULL;

---- CASE ---- 是 SQL 用来做为 IF-THEN-ELSE 之类逻辑的关键字
语法:
SELECT CASE ("栏位名")
  WHEN "条件1” THEN "结果1"
  WHEN "条件2" THEN "结果2"
  ...
  [ELSE "结果N"]
  END
FROM "表名";

#"条件"可以是一个数值或是公式。ELSE子句则并不是必须的。

SELECT store_Name, CASE Store_Name
  WHEN 'Los Angeles' THEN Sales * 2
  WHEN 'Boston' THEN Sales * 1.5
  ELSE Sales
  END
"New Sales",Date
FROM Store_Info;

#"New Sales"是用于CASE 那个栏位的栏位名。

CREATE TABLE Total_Sales (Name char(10),sales int(5));
INSERT INTO Total_Sales VALUES ('zhangsan',10);
INSERT INTO Total_Sales VALUES ('lisi',15);
INSERT INTO Total_Sales VALUES ('wangwu',20);
INSERT INTO Total_Sales VALUES ('zhaoliu',40);
INSERT INTO Total_Sales VALUES ('sunqi',50);
INSERT INTO Total_Sales VALUES ('zhouba',20);
INSERT INTO Total_Sales VALUES ('wujiu',30);

----算排名----表格自我连结(Self Join)，然后将结果依序列出，算出每一行之前〈包含那一行本身)有多少行数
SELECT A1.Name, A1.sales,COUNT(A2.sales) Rank FROM Total_sales A1,Total_sales A2
WHERE A1.sales < A2.sales 0R (A1.sales = A2.sales AND A1.Name = A2.Name)
GROUP BY A1.Name, A1.sales ORDER BY A1.sales DESC;

例如：
select A1.Name,A1.sales,count(A2.sales) rank from Total_Sales A1,Total_Sales A2 where A1.sales <  A2.sales OR (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;

解释：
当A1的sales字段值小于A2的sales字段值、或者两表sales字段值相等并且Name字段值相等时，
从A1和A2表中查询A1的Name字段值、A1的sales字段值、和A2的sales字段的非空值rank是别名，并为A1的Name字段分组，A1的sales字段降序排序

---- 算中位数 ----
SELECT Sales Middle FROM (SELECT A1.Name,A1.Sales,COUNT(A2.Sales) Rank FROM Total_Sales A1,Total_Sales A2
WHERE A1.Sales < A2.Sales 0R (A1.Sales = A2.Sales AND A1.Name >= A2.Name)
GROUP BY A1.Name,A1.Sales ORDER BY A1.Sales DESC) A3
WHERE A3.Rank = (SELECT (COUNT(*)+1) DIV 2 FROM Total_Sales);

例如：
select * from (select A1.Name,A1.sales,count(A2.sales) rank from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales OR (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc) A3 where A3.rank = (select (count(*)+1) DIV 2 from Total_Sales);

select sales mid from (select A1.Name,A1.sales,count(A2.sales) rank from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales OR (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc) A3 where A3.rank = (select (count(*)+1) DIV 2 from Total_Sales);


#每个派生表必须有自己的别名，所以别名A3必须要有
#DIV 是在MySQL中算出商的方式

---- 算累积总计 ---- 表格自我连结(Self Join)，然后将结果依序列出,算出每一行之前(包含那一行本身)的总合
SELECT A1.Name, A1.Sales, SUM(A2.Sales) Sum_Total FROM Total_Sales A1，Total_Sales A2
WHERE A1.Sales < A2.Sales OR (A1.Sales=A2.Sales AND A1.Name = A2.Name)
GROUP BY A1.Name,A1.Sales ORDER BY A1.Sales DESC;

例如：
select A1.*,sum(A2.sales) sum_soales from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or(A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;

例如：
select A1.*,A1.sales/(select sum(sales) from Total_Sales) z_sum from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name;

#select sum(sales) from Total_Sales 是为了算出字段值总合，然后每一行一一除以总合，算出每行的总合百分比。

例如：
select A1.Name,A1.sales,sum(A2.sales),sum(A2.sales)/(select sum(sales) from Total_Sales) Z from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;

select A1.Name,A1.sales,sum(A2.sales),TRUNCATE(sum(A2.sales)/(select sum(sales) from Total_Sales),2) ||'%' Z from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;

例如：
create table SITE(site varchar(20));
insert into SITE values('nanjing');
insert into SITE values('beijing');
insert into SITE values('');
insert into SITE values('taijin');
insert into SITE values();
insert into SITE values('');
select * from SITE;	

select length(site) from SITE;
select * from SITE where site is NULL;
select * from SITE where site is not NULL;
select * from SITE where site ='';
select * from SITE where site <> '';

匹配模式			描述									实例
^ 				匹配文本的开始字符 						‘^bd' 匹配以 bd 开头的字符串
$ 				匹配文本的结束字符 						‘qn$' 匹配以 qn 结尾的字符串
. 				匹配任何单个字符							‘s.t' 匹配任何 s 和 t 之间有一个字符的字符串
* 				匹配零个或多个在它前面的字符 				‘fo*t' 匹配 t 前面有任意个 o
+ 				匹配前面的字符 1 次或多次					‘hom+' 匹配以 ho 开头，后面至少一个m 的字符串
字符串 			匹配包含指定的字符串 						‘clo' 匹配含有 clo 的字符串
p1|p2 			匹配 p1 或 p2 							‘bg|fg' 匹配 bg 或者 fg
[...] 			匹配字符集合中的任意一个字符 				‘[abc]' 匹配 a 或者 b 或者 c
[^...] 			匹配不在括号中的任何字符 					‘[^ab]' 匹配不包含 a 或者 b 的字符串
{n} 			匹配前面的字符串 n 次 					‘g{2}' 匹配含有 2 个 g 的字符串
{n,m}			匹配前面的字符串至少 n 次，至多m 次		‘f{1,3}' 匹配 f 最少 1 次，最多 3 次

例如：
select * from Total_Sales where Name regexp '^[n]';
select * from Total_Sales where Name regexp '[n]';
select * from Total_Sales where Name regexp 'Ho|Bo';

语法：
DELIMITER !!    				#将语句的结束符号从分号；临时修改，以防出问题，可以自定义
CREATE PROCEDURE XXX()  	#创建存储过程，过程名自定义,（）可带参数
 	BEGIN   		    	#过程体以关键字BEGIN开始
 	select * from xxx;  	#过程体语句
 	END!!    				#过程体以关键字END结尾
DELIMITER ; 			    	#将语句的结束符号恢复为分号

call XXX;	  				#调用存储过程

====查看存储过程====
show create procedure [数据库.]储存过程名; 	  #查看某个储存过程的具体信息
show create procedure XXX;
show procedure status [like '%XXX%'] \G

例如：
DELIMITER !!
CREATE PROCEDURE KIND1()
BEGIN
	select * from Total_Sales;
END!!

DELIMITER ;
CALL KIND1;

show create procedure KIND1\G
show procedure status like '%KIND1%'\G

例如：
DELIMITER !!
CREATE PROCEDURE KIND2(IN people char(20))
BEGIN
	select * from Total_Sales where Name=people;                                                    
END!!         

DELIMITER ;
CALL KIND2('lisi');

例如：
DELIMITER !!
CREATE PROCEDURE KIND7(IN num int(10))
BEGIN
declare var int;
set var=num*2;
if var>=10 then
	update Total_Sales set sales=sales+1;
else 
	update Total_Sales set sales=sales-1;
end if;
END!!
DELIMITER ;

CALL KIND7(5);
CALL KIND7(4);

例如：
create table akg(id int);

DELIMITER !!
CREATE PROCEDURE KIND6()
BEGIN
declare var int;
set var=0;
while var<5 do
	insert into akg values(var);
	set var=var+1;
end while;
END!!

DELIMITER ;
CALL KIND6;
select * from akg;