mysql-----sql语句（一）

mysql-----sql语句（一）

-- 字符集：  utf8mb4 -- UTF-8 Unicode
-- 排序规则：  utf8mb4_general_ci


-- 创库
create database test2 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

-- 创表
CREATE table tutorials_tbl(
   tutorial_id INT NOT NULL AUTO_INCREMENT,
   tutorial_title VARCHAR(100) NOT NULL,
   tutorial_author VARCHAR(40) NOT NULL,
   submission_date DATE,
   PRIMARY KEY ( tutorial_id )
);

-- 删表
drop table tutorials_tbl;


-- 插入数据

INSERT INTO tutorials_tbl 
        (tutorial_id,tutorial_title,tutorial_author,submission_date) 
         VALUES
       (1001,"LEARN MYSQL","ABDUL S",NOW());
       
       
-- 删除表里数据

DELETE FROM table_name
    WHERE
    table_name.some_colume="some_value";
    

DELETE from  tutorials_tbl where tutorial_id="1002";

-- 更新
UPDATE table_name   
    SET test_column1="test22_column1" 
    where 
    table_name.some_colume="some_value";
    

UPDATE tutorials_tbl 
    set  tutorials_tbl.tutorial_author = "eeewww" 
    where 
    tutorials_tbl.tutorial_id=1004 AND tutorials_tbl.tutorial_title="python";
    
    
-- MySQL 取第1条数据  LIMIT
SELECT * from  ysl.tutorials_tbl LIMIT 1; 


-- LIKE  通配符（%）
SELECT * from tutorials_tbl 
    where tutorials_tbl.tutorial_title LIKE "%MYSQL%";

    
-- IN 操作符允许在WHERE 子句中规定多个值。
SELECT * FROM TABLE_NAME
    WHERE TABLE_NAME.colume1 IN (value1, value2);

SELECT * from tutorials_tbl 
    where tutorials_tbl.tutorial_title  IN ("LEARN MYSQL","LEARN MYSQL1")
    
    
-- BETWEEN   某个值什么之间
SELECT * from tutorials_tbl 
    where tutorials_tbl.tutorial_id  BETWEEN 1001 and 1003;    
    
    
    
-- sql 别名 1 列别名     2 表别名

SELECT colume_id as id from table_name;


SELECT * from table_name as t 
    where t.colume_id="1001"

 INNER JOIN

--SQL 连接(JOIN) 


SELECT * from access_log;
+-----+---------+-------+---------------------+
| aid | site_id | count | date                |
+-----+---------+-------+---------------------+
|   1 |       1 |    45 | 2018-10-10 23:20:05 |
|   2 |       3 |   100 | 2018-10-10 23:20:05 |
|   3 |       1 |   230 | 2018-10-10 23:20:05 |
|   4 |       2 |    10 | 2018-10-10 23:20:05 |
|   5 |       5 |   205 | 2018-10-10 23:20:05 |
|   6 |       4 |    13 | 2018-10-10 23:20:05 |
|   7 |       3 |   220 | 2018-10-10 23:20:05 |
|   8 |       5 |   545 | 2018-10-10 23:20:05 |
|   9 |       3 |   201 | 2018-10-10 23:20:05 |
+-----+---------+-------+---------------------+



SELECT * from Websites;
+----+---------------+----------------------------+-------+---------+
| id | name          | url                        | alexa | country |
+----+---------------+----------------------------+-------+---------+
|  1 | Google        | https://www.google.cm/     |     1 | USA     |
|  2 | 淘宝          | https://www.taobao.com/    |    13 | CN      |
|  3 | 菜鸟教程      | https://www.runoob.com/    |  4689 | CN      |
|  4 | 微博          | https://weibo.com/         |    20 | CN      |
|  5 | Facebook      | https://www.facebook.com/  |     3 | USA     |
|  7 | stackoverflow | https://stackoverflow.com/ |     0 | IND     |
+----+---------------+----------------------------+-------+---------+


SELECT Websites.id, Websites.name, access_log.count,access_log.date
        from Websites
        INNER JOIN access_log
        on Websites.id=access_log.site_id;
+----+--------------+-------+---------------------+
| id | name         | count | date                |
+----+--------------+-------+---------------------+
|  1 | Google       |    45 | 2018-10-10 23:20:05 |
|  1 | Google       |   230 | 2018-10-10 23:20:05 |
|  2 | 淘宝         |    10 | 2018-10-10 23:20:05 |
|  3 | 菜鸟教程     |   100 | 2018-10-10 23:20:05 |
|  3 | 菜鸟教程     |   220 | 2018-10-10 23:20:05 |
|  3 | 菜鸟教程     |   201 | 2018-10-10 23:20:05 |
|  4 | 微博         |    13 | 2018-10-10 23:20:05 |
|  5 | Facebook     |   205 | 2018-10-10 23:20:05 |
|  5 | Facebook     |   545 | 2018-10-10 23:20:05 |
+----+--------------+-------+---------------------+


-- INNER JOIN：如果表中有至少一个匹配，则返回行
-- LEFT JOIN：即使右表中没有匹配，也从左表返回所有的行
-- RIGHT JOIN：即使左表中没有匹配，也从右表返回所有的行
-- FULL JOIN：只要其中一个表中存在匹配，则返回行

-- 首先，连接的结果可以在逻辑上看作是由SELECT语句指定的列组成的新表。
-- 左连接与右连接的左右指的是以两张表中的哪一张为基准，它们都是外连接。
-- 外连接就好像是为非基准表添加了一行全为空值的万能行，用来与基准表中找不到匹配的行进行匹配。假设两个没有空值的表进行左连接，左表是基准表，左表的所有行都出现在结果中，右表则可能因为无法与基准表匹配而出现是空值的字段。

-- SQL INNER JOIN 语法
SELECT column_name(s)
    FROM table1
    INNER JOIN table2
    ON table1.column_name=table2.column_name;
或：
SELECT column_name(s)
    FROM table1
    JOIN table2
    ON table1.column_name=table2.column_name;
    
-- INNER JOIN 与 JOIN 是相同的。

 LEFT JOIN 

 LEFT JOIN 
 
SELECT column_name(s)
    FROM table1
    LEFT JOIN table2
    ON table1.column_name=table2.column_name;
或：

SELECT column_name(s)
    FROM table1
    LEFT OUTER JOIN table2
    ON table1.column_name=table2.column_name;
    
    
-- 注释：在某些数据库中，LEFT JOIN 称为 LEFT OUTER JOIN

SELECT Websites.id, Websites.name, access_log.count,access_log.date
from Websites
LEFT JOIN access_log
on Websites.id=access_log.site_id;


+----+---------------+-------+---------------------+
| id | name          | count | date                |
+----+---------------+-------+---------------------+
|  1 | Google        |    45 | 2018-10-10 23:20:05 |
|  3 | 菜鸟教程      |   100 | 2018-10-10 23:20:05 |
|  1 | Google        |   230 | 2018-10-10 23:20:05 |
|  2 | 淘宝          |    10 | 2018-10-10 23:20:05 |
|  5 | Facebook      |   205 | 2018-10-10 23:20:05 |
|  4 | 微博          |    13 | 2018-10-10 23:20:05 |
|  3 | 菜鸟教程      |   220 | 2018-10-10 23:20:05 |
|  5 | Facebook      |   545 | 2018-10-10 23:20:05 |
|  3 | 菜鸟教程      |   201 | 2018-10-10 23:20:05 |
|  7 | stackoverflow |  NULL | NULL                |
+----+---------------+-------+---------------------+

 LEFT JOIN 关键字从左表（Websites）返回所有的行，即使右表（access_log）中没有匹配。

 RIGHT JOIN

--RIGHT JOIN

SELECT column_name(s)
FROM table1
RIGHT JOIN table2
ON table1.column_name=table2.column_name;


SELECT Websites.name, access_log.count, access_log.date
    FROM access_log
    RIGHT JOIN Websites
    ON access_log.site_id=Websites.id
    ORDER BY access_log.count DESC;


+---------------+-------+---------------------+
| name          | count | date                |
+---------------+-------+---------------------+
| Facebook      |   545 | 2018-10-10 23:20:05 |
| Google        |   230 | 2018-10-10 23:20:05 |
| 菜鸟教程      |   220 | 2018-10-10 23:20:05 |
| Facebook      |   205 | 2018-10-10 23:20:05 |
| 菜鸟教程      |   201 | 2018-10-10 23:20:05 |
| 菜鸟教程      |   100 | 2018-10-10 23:20:05 |
| Google        |    45 | 2018-10-10 23:20:05 |
| 微博          |    13 | 2018-10-10 23:20:05 |
| 淘宝          |    10 | 2018-10-10 23:20:05 |
| stackoverflow |  NULL | NULL                |
+---------------+-------+---------------------+

 

-- 　　UNION 操作符合并两个或多个 SELECT 语句的结果。   2个表相同中相同的列名

-- 　　UNION 操作符用于合并两个或多个 SELECT 语句的结果集。

-- 　　请注意，UNION 内部的每个 SELECT 语句必须拥有相同数量的列。列也必须拥有相似的数据类型。同时，每个 SELECT 语句中的列的顺序必须相同。

--　　 ALL: 可选，返回所有结果集，包含重复数据。


SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;
-- UNION 操作符选取不同的值。如果允许重复的值，请使用 UNION ALL。


SELECT column_name(s) FROM table1
UNION ALL
SELECT column_name(s) FROM table2;

 UNION

SELECT * FROM Websites;
+----+---------------+----------------------------+-------+---------+
| id | name          | url                        | alexa | country |
+----+---------------+----------------------------+-------+---------+
|  1 | Google        | https://www.google.cm/     |     1 | USA     |
|  2 | 淘宝          | https://www.taobao.com/    |    13 | CN      |
|  3 | 菜鸟教程      | https://www.runoob.com/    |  4689 | CN      |
|  4 | 微博          | https://weibo.com/         |    20 | CN      |
|  5 | Facebook      | https://www.facebook.com/  |     3 | USA     |
|  7 | stackoverflow | https://stackoverflow.com/ |     0 | IND     |
+----+---------------+----------------------------+-------+---------+


SELECT * FROM apps;
+----+------------+--------------------------+---------+
| id | app_name   | url                      | country |
+----+------------+--------------------------+---------+
|  1 | QQ APP     | http://im.qq.com/        | CN      |
|  2 | 微博 APP   | http://weibo.com/        | CN      |
|  3 | 淘宝 APP   | https://www.taobao.com/  | CN      |
+----+------------+--------------------------+---------+

-- 去重
SELECT country FROM Websites
UNION
SELECT country FROM apps
ORDER BY country;
+---------+
| country |
+---------+
| CN      |
| IND     |
| USA     |
+---------+

-- 不去重复
SELECT country FROM Websites
UNION ALL
SELECT country FROM apps
ORDER BY country;
+---------+
| country |
+---------+
| CN      |
| CN      |
| CN      |
| CN      |
| CN      |
| CN      |
| IND     |
| USA     |
| USA     |
+---------+


SELECT country, name FROM Websites
WHERE country='CN'
UNION ALL
SELECT country, app_name FROM apps
WHERE country='CN'
ORDER BY country;
+---------+--------------+
| country | name         |
+---------+--------------+
| CN      | QQ APP       |
| CN      | 微博 APP     |
| CN      | 淘宝 APP     |
| CN      | 淘宝         |
| CN      | 菜鸟教程     |
| CN      | 微博         |
+---------+--------------+

 参考

http://www.runoob.com