數據庫表操作，MySQL索引，MySQL視圖

數據庫的表操作

1. 插入 insert

表結構

	+-------+-------------+------+-----+---------+-------+
	| Field | Type        | Null | Key | Default | Extra |
	+-------+-------------+------+-----+---------+-------+
	| ip    | int(11)     | YES  |     | NULL    |       |
	| port  | varchar(10) | YES  |     | NULL    |       |
	+-------+-------------+------+-----+---------+-------+

完整插入insert into 表名 values （值1.值2）；
insert into test.service values(100,‘80’);

指定字段插入數據
insert into 表名（字段1，字段2） values （值1.值2）；
插入多條記錄
insert into 表名 values （值1.值2），（值1.值2）；

2，查詢 select

表結構

+----+-------+------------+----------+--------+--------+
| id | name  | hire_date  | salary   | office | dep_id |
+----+-------+------------+----------+--------+--------+
|  1 | jack  | 2019-07-11 |  5000.00 |    501 |    100 |
|  2 | ma    | 2019-07-11 |  6000.00 |    501 |    100 |
|  3 | alice | 2019-07-11 |  7000.00 |    501 |    100 |
|  4 | tian  | 2019-07-11 | 14000.00 |    502 |    101 |
|  5 | harry | 2019-01-11 |  3000.00 |    502 |    101 |
|  6 | zhu   | 2019-07-11 |  2200.00 |    503 |    102 |
+----+-------+------------+----------+--------+--------+

單表查詢

	簡單查詢
	
		select * from enploy;
	
	去重：
	
		mysql> select distinct office from enploy;
		+--------+
		| office |
		+--------+
		|    501 |
		|    502 |
		|    503 |
		+--------+

單條件查詢

單條件查詢
	mysql> select name,salary from enploy where salary>5000;
	+-------+----------+
	| name  | salary   |
	+-------+----------+
	| ma    |  6000.00 |
	| alice |  7000.00 |
	| tian  | 14000.00 |
	+-------+----------+

多條件查詢
mysql> select name ,salary,office from enploy where salary>5000 AND office=501;
+-------+---------+--------+
| name  | salary  | office |
+-------+---------+--------+
| ma    | 6000.00 |    501 |
| alice | 7000.00 |    501 |
+-------+---------+--------+

集合查詢in
mysql> select name ,salary from enploy where salary in (5000,6000,7000);
+-------+---------+
| name  | salary  |
+-------+---------+
| jack  | 5000.00 |
| ma    | 6000.00 |
| alice | 7000.00 |
+-------+---------+

關鍵字模糊查詢like
'% '表示任意多個字符
'_ '表示任意一個字符
mysql> select name,salary from enploy where name like 'al%';
+-------+---------+
| name  | salary  |
+-------+---------+
| alice | 7000.00 |
+-------+---------+

排序

單列排序 ORDER BY
DESC  降序
AESC  升序

按時間降序
mysql> select * from enploy ORDER BY hire_date DESC;
+----+-------+------------+----------+--------+--------+
| id | name  | hire_date  | salary   | office | dep_id |
+----+-------+------------+----------+--------+--------+
|  1 | jack  | 2019-07-11 |  5000.00 |    501 |    100 |
|  2 | ma    | 2019-07-11 |  6000.00 |    501 |    100 |
|  3 | alice | 2019-07-11 |  7000.00 |    501 |    100 |
|  4 | tian  | 2019-07-11 | 14000.00 |    502 |    101 |
|  6 | zhu   | 2019-07-11 |  2200.00 |    503 |    102 |
|  5 | harry | 2019-01-11 |  3000.00 |    502 |    101 |
+----+-------+------------+----------+--------+--------+
取排序後的前幾位limit
mysql> select * from enploy ORDER BY hire_date DESC limit 5;

分組查詢：把dep_id相同的name組成一個組
mysql> select dep_id,group_concat(name) from enploy group by dep_id;
+--------+--------------------+
| dep_id | group_concat(name) |
+--------+--------------------+
|    100 | jack,ma,alice      |
|    101 | tian,harry         |
|    102 | zhu                |
+--------+--------------------+

字符串匹配的方式：
where name = ‘alice’
where name like ‘ali%’
where name regexp ‘^ali’

多表查詢
兩個表數據

mysql> select * from employe;
+--------+----------+------+--------+
| emp_id | emp_name | age  | dep_id |
+--------+----------+------+--------+
|      1 | tianyun  |   19 |    200 |
|      2 | tom      |   26 |    201 |
|      3 | jack     |   30 |    201 |
|      4 | alice    |   24 |    202 |
|      5 | robin    |   40 |    200 |
|      6 | natasha  |   28 |    204 |
+--------+----------+------+--------+

mysql> select * from department;
+--------+----------+
| dep_id | dep_name |
+--------+----------+
|    200 | hr       |
|    201 | it       |
|    202 | sale     |
|    203 | fd       |
+--------+----------+

內連接：只找出匹配的行(沒有natasha)

mysql> select employe.emp_name,employe.age,employe.dep_id,department.dep_name from employe,department where employe.dep_id = department.dep_id;
+----------+------+--------+----------+
| emp_name | age  | dep_id | dep_name |
+----------+------+--------+----------+
| tianyun  |   19 |    200 | hr       |
| tom      |   26 |    201 | it       |
| jack     |   30 |    201 | it       |
| alice    |   24 |    202 | sale     |
| robin    |   40 |    200 | hr       |
+----------+------+--------+----------+

左，右連接查詢
語法：select 字段列表 from 表1 left | right join 表2 on 表1.字段 = 表2.字段；

找出所有員工及所屬部門，包括沒有部門的員工
mysql> select emp_id,emp_name,dep_name from employe left join department on employe.dep_id = department.dep_id;
+--------+----------+----------+
| emp_id | emp_name | dep_name |
+--------+----------+----------+
|      1 | tianyun  | hr       |
|      5 | robin    | hr       |
|      2 | tom      | it       |
|      3 | jack     | it       |
|      4 | alice    | sale     |
|      6 | natasha  | NULL     |
+--------+----------+----------+

找出所有部門包含的員工，包括空部門
mysql> select emp_id,emp_name,dep_name from employe right join department on employe.dep_id = department.dep_id;
+--------+----------+----------+
| emp_id | emp_name | dep_name |
+--------+----------+----------+
|      1 | tianyun  | hr       |
|      2 | tom      | it       |
|      3 | jack     | it       |
|      4 | alice    | sale     |
|      5 | robin    | hr       |
|   NULL | NULL     | fd       |
+--------+----------+----------+

複合查詢

找出所有部門年齡大於25的員工
mysql> select emp_id,emp_name,age,dep_name from employe,department where employe.dep_id = department.dep_id and age>25;
+--------+----------+------+----------+
| emp_id | emp_name | age  | dep_name |
+--------+----------+------+----------+
|      2 | tom      |   26 | it       |
|      3 | jack     |   30 | it       |
|      5 | robin    |   40 | hr       |
+--------+----------+------+----------+

帶比較運算符的子查詢
查詢年齡大於等於25歲員工所在部門
mysql> select dep_id,dep_name from department where dep_id IN (select distinct dep_id from employe where age >= 25);
+--------+----------+
| dep_id | dep_name |
+--------+----------+
|    201 | it       |
|    200 | hr       |
+--------+----------+

帶exists關鍵字子查詢
exists存在時，內層查詢返回true和false，爲true，外層查詢語句進行查詢，false不查詢。
mysql> select * from employe 
    -> where exists (select * from department where dep_id = 203);
+--------+----------+------+--------+
| emp_id | emp_name | age  | dep_id |
+--------+----------+------+--------+
|      1 | tianyun  |   19 |    200 |
|      2 | tom      |   26 |    201 |
|      3 | jack     |   30 |    201 |
|      4 | alice    |   24 |    202 |
|      5 | robin    |   40 |    200 |
|      6 | natasha  |   28 |    204 |
+--------+----------+------+--------+
6 rows in set (0.00 sec)

mysql> select * from employe  where exists (select * from department where dep_id = 300);
Empty set (0.00 sec)

mysql 索引

創建索引
創建表的時候創建索引（插入數據慢）
create 在已創建表上加索引
查看並測試索引
刪除索引

1. 創建表

   mysql> create table t3(id int ,name varchar(10));
   

2. 創建存儲過程

   mysql> delimiter $$    //改變結束符爲$$  delimiter == \d
   mysql> create procedure autoinsert1() //創建存儲過程
       -> BEGIN //開始
       -> declare i int default 1; //設定一個變量默認值爲1
       -> while (i<50000)do 
       ->     insert into company.t3 values (i,'aaa');
       ->     set i=i+1;
       -> end while;
       -> END$$ //結束
   

3. 查看存儲過程

    mysql> show create procedure autoinsert1\G
   *************************** 1. row ***************************
              Procedure: autoinsert1
               sql_mode: STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION
       Create Procedure: CREATE DEFINER=`root`@`localhost` PROCEDURE `autoinsert1`()
   BEGIN
   declare i int default 1;
   while (i<50000)do
       insert into company.t3 values (i,'aaa');
       set i=i+1;
   end while;
   END
   character_set_client: utf8
   collation_connection: utf8_general_ci
     Database Collation: latin1_swedish_ci
   1 row in set (0.00 sec)
   

4. 調用函數

   mysql> call autoinsert1();
   

創建索引

1. 創建表時創建索引
   語法：
   create table表名（
   字段1 數據類型，
   字段2 數據類型，
   [UNIQUE | FULLTEXT | SPATIAL ] INDEX | KEY [索引名] (字段名[(長度)] [ASC|DESC])
   ）

   創建普通索引
   create table t1(
   	dep_id int,
   	dep_name varchar(30),
   	comment varchar(30),
   	INDEX ~~別名1~~ (dep_name)
   );
   
   創建唯一索引
   create table t2(
   	dep_id int,
   	dep_name varchar(30),
   	comment varchar(30),
   	UNIQUE INDEX ~~別名1~~ (dep_name)
   ); 
   
   創建全文索引
   create table department1(
   	dep_id int,
   	dep_name varchar(30),
   	comment varchar(30),
   	log text,
   	FULLTEXT INDEX ~~別名1~~ (log)
   );
   
   創建多列索引
   create table department1(
   		dep_id int,
   		dep_name varchar(30),
   		comment varchar(30),
   		log text,
   		INDEX ~~別名1~~ (dep_name,comment)
   	);
   

2. 在存在的表上創建索引
   語法：
   create [UNIQUE | FULLTEXT | SPATIAL ] INDEX 索引名 ON 表名 （字段名[(長度）] [asc|desc]）;

    創建普通索引
    create index comment_index on t1(comment);
   
   創建唯一索引
   create UNIQUE INDEX 	comment_index on t1(comment);
   
   創建全文索引
   create FULLTEXT INDEX log_index on department1(log);
   
   創建多例索引
   create INDEX dep_name_comment ON department1(dep_name,comment);
   

注：創建標的時候創建索引，可以不加索引名，這時索引名爲字段名，添加索引時候，一定要加索引名
查看索引
語法：
show create table 表名\G

mysql> show create table t3;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                       |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------+
| t3    | CREATE TABLE `t3` (
  `id` int(11) DEFAULT NULL,
  `name` varchar(10) DEFAULT NULL,
  KEY `id_index` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

3. 刪除索引
   語法：
   drop index 索引名 ON 表名；

    mysql> drop index id_index on t3;
    Query OK, 0 rows affected (0.02 sec)
    Records: 0  Duplicates: 0  Warnings: 0
   

查詢對比
沒有索引

看怎麼查
mysql> explain select * from t3 where id=49000\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t3
         type: ALL
possible_keys: NULL
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 50344
        Extra: Using where
1 row in set (0.00 sec)

看查詢時間
mysql> select * from t3 where id=49000;
+-------+------+
| id    | name |
+-------+------+
| 49000 | aaa  |
+-------+------+
1 row in set (0.01 sec)

有索引

怎麼查
mysql> explain select * from t3 where id = 49000\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t3
         type: ref
possible_keys: id_index
          key: id_index
      key_len: 5
          ref: const
         rows: 1
        Extra: NULL
1 row in set (0.00 sec)
時間
mysql> select * from t3 where id = 49000;
+-------+------+
| id    | name |
+-------+------+
| 49000 | aaa  |
+-------+------+
1 row in set (0.00 sec)

注：索引查詢會讓查詢速度更快，查詢的時候要帶上索引名條件

mysql 視圖

視圖其實是一個自定義虛擬表，不在數據庫中以存儲的數據形式存在，而是對已存在的數據拼湊出來的新表，便於查詢。

• 創建視圖
  語法：create view 視圖名
  as select語句；

   兩張表
   
   mysql> select * from product;
   +----+--------+-------+
   | id | name   | price |
   +----+--------+-------+
   |  1 | apple  |    10 |
   |  2 | orange |     5 |
   |  3 | pear   |    12 |
   +----+--------+-------+
   3 rows in set (0.00 sec)
   
   mysql> select * from purchase;
   +----+--------+----------+---------------------+
   | id | name   | quantity | gen_time            |
   +----+--------+----------+---------------------+
   |  1 | apple  |        8 | 2019-07-26 15:28:44 |
   |  2 | orange |        5 | 2019-07-26 15:28:44 |
   |  3 | pear   |        6 | 2019-07-26 15:28:44 |
   +----+--------+----------+---------------------+
   3 rows in set (0.00 sec)
  
   創建視圖
   mysql> create view u AS select product.name,product.price,purchase.quantity,purchase.quantity * product.price as total from product,purchase where product.name=purchase.name;
   
   mysql> show tables;
   +----------------+
   | Tables_in_shop |
   +----------------+
   | product        |
   | purchase       |
   | u              |
   +----------------+
   3 rows in set (0.00 sec)
   
   mysql> select * from u;
   +--------+-------+----------+-------+
   | name   | price | quantity | total |
   +--------+-------+----------+-------+
   | apple  |    10 |        8 |    80 |
   | orange |     5 |        5 |    25 |
   | pear   |    12 |        6 |    72 |
   +--------+-------+----------+-------+
  
  
   修改視圖：
   先刪除視圖，drop view 視圖名
   再重新創建
  

mysql觸發器

1. 觸發器案例
   
   
   觸發器的刪除必須通過主鍵刪除，主鍵是唯一的。
   
   數據的更改，觸發器需要將所有的字段重新獲取一遍，通過主鍵獲取所有字段。