MYSQL高级SQL语句

目录

一、环境准备

二、高级SQL语句

三、通配符（通常通配符都是跟 LIKE 一起使用的）

四、函数

---

一、环境准备

create database kgc;
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');


location 表格
+----------+--------------+
| Region   | Store_Name   |
|----------+--------------|
| East     | Boston       |
| East     | New York     |
| West     | Los Angeles  |
| 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');

Store_Info 表格
+--------------+---------+------------+
| Store_Name   |   Sales | Date       |
|--------------+---------+------------|
| Los Angeles  |    1500 | 2020-12-05 |
| Houston      |     250 | 2020-12-07 |
| Los Angeles  |     300 | 2020-12-08 |
| Boston       |     700 | 2020-12-08 |
+--------------+---------+------------+

二、高级SQL语句

---- SELECT ----显示表格中一个或数个字段的所有数据记录
语法：SELECT "字段" FROM "表名";
SELECT Store_Name FROM Store_Info;

---- DISTINCT ----不显示重复的数据记录
语法：SELECT DISTINCT "字段" FROM "表名";
SELECT DISTINCT Store_Name FROM Store_Info;

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

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

---- IN ----显示已知的值的数据记录
语法：SELECT "字段" FROM "表名" WHERE "字段" 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数据记录
语法：SELECT "字段" FROM "表名" WHERE "字段" BETWEEN '值1' AND '值2';
SELECT * FROM Store_Info WHERE Date BETWEEN '2020-12-06' AND '2020-12-10';

三、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，'ABZ' 和 'A2Z' 都符合这一个模式，而 'AKKZ' 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，'SAN FRANCISCO' 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数据记录）

语法：SELECT "字段" FROM "表名" WHERE "字段" LIKE {模式};
SELECT * FROM Store_Info WHERE Store_Name like '%os%';

---- ORDER BY ----按关键字排序
语法：SELECT "字段" FROM "表名" [WHERE "条件"] ORDER BY "字段" [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;

四、函数

数学函数：
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(x)?? ??? ??? ??? ?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，也可以返回多个字段的最大的值
least(x1,x2...)?? ??? ?返回集合中最小的值，也可以返回多个字段的最小的值

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;

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';
#拼接字符串

#如sql_mode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后面的字段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，凡是在 GROUP BY 后面出现的字段，必须在 SELECT 后面出现；
凡是在 SELECT 后面出现的、且未在聚合函数中出现的字段，必须出现在 GROUP BY 后面

语法：SELECT "字段1", SUM("字段2") FROM "表名" GROUP BY "字段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。
语法：SELECT "字段1", SUM("字段2") FROM "表格名" GROUP BY "字段1" HAVING (函数条件);
?

SELECT Store_Name, SUM(Sales) FROM Store_Info GROUP BY Store_Name HAVING SUM(Sales) > 1500;

别名（字段別名 表格別名）

语法：SELECT "表格別名"."字段1" [AS] "字段別名" FROM "表格名" [AS] "表格別名";

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 "字段1" FROM "表格1" WHERE "字段2" [比较运算符] ?? ??? ??? ??? ?#外查询
(SELECT "字段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 "字段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');

连接查询

location 表格
+----------+--------------+
| Region   | Store_Name   |
|----------+--------------|
| East     | Boston       |
| East     | New York     |
| West     | Los Angeles  |
| West     | Houston      |
+----------+--------------+

UPDATE Store_Info SET store_name='Washington' WHERE sales=300;
Store_Info 表格
+--------------+---------+------------+
| Store_Name   |   Sales | Date       |
|--------------+---------+------------|
| Los Angeles  |    1500 | 2020-12-05 |
| Houston      |     250 | 2020-12-07 |
| Washington   |     300 | 2020-12-08 |
| Boston       |     700 | 2020-12-08 |
+--------------+---------+------------+

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 RIGHT JOIN Store_Info B on A.Store_Name = B.Store_Name ;

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

内连接一：

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

内连接二：

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;

UNION（联集，将两个SQL语句的结果合并起来，两个SQL语句所产生的字段需要是同样的数据记录种类）

UNION ：生成结果的数据记录值将没有重复，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 ：将生成结果的数据记录值都列出来，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);

#取两个SQL语句结果的交集，且没有重复

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

SELECT DISTINCT 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;

SELECT A.Store_Name FROM (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 A.Store_Name FROM 
(SELECT DISTINCT Store_Name FROM location UNION ALL SELECT DISTINCT Store_Name FROM Store_Info) A 
GROUP BY A.Store_Name HAVING COUNT(*) > 1;

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;

SELECT A.Store_Name FROM 
(SELECT DISTINCT Store_Name FROM location UNION ALL SELECT DISTINCT Store_Name FROM Store_Info) A 
GROUP BY A.Store_Name HAVING COUNT(*) = 1;