Python中操做mysql知識（二）

時間  2019-11-13
標籤 python mysql 知識 欄目 Python 简体版
原文   原文鏈接

1.建立表Teacher：

create table Teacher(
	teaId int not null,
	teaname varchar(100),
	age int,
	sex enum('M', 'F'),
	phone int);

注意：python

    char 和varchar區別：ide

    ‘123’    ------>varchar(10)       #  3位測試

    '123       '  -------> char(10)    # 10位    不足10位空格補全spa

查看新建的Teacher表：code

MariaDB [(none)]> use test;
Database changed
MariaDB [test]> show tables;
+----------------+
| Tables_in_test |
+----------------+
| Teacher        |
+----------------+
1 row in set (0.00 sec)

2.創建超級用戶：

grant all privileges on *.* to 'fxq'@'%' identified by '123456' with grant option;

3.插入數據：

insert into Teacher(teaid,teaname,age) values(1,'feng',20);

插入多行數據：

insert into Teater(teaid,teaname,age) values(101,'fengxiaoqing',20),(102,'zhangsan',30),(103,'wangwu',40);

查看插入的數據：

MariaDB [test]> select * from Teacher;
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     1 | feng         |   20 | NULL |       NULL |
|     2 | wang         |   20 | M    | 2147483647 |
|     2 | wang         |   20 | M    | 2147483647 |
|     3 | zhang        |   30 | M    | 2147483647 |
|     4 | li           |   40 | M    | 2147483647 |
|     5 | zhao         |   50 | F    | 2147483647 |
|     5 | zhao         |   50 | F    | 1821113120 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
|   102 | zhangsan     |   30 | NULL |       NULL |
|   103 | wangwu       |   40 | NULL |       NULL |
+-------+--------------+------+------+------------+
10 rows in set (0.00 sec)

MariaDB [test]>

4.數據查詢：

select *  from Teacher where teaId > 4;

select * from Teacher where teaId in(1,4,101);

select * from Teacher where teaId like ('%1%');

測試結果：

MariaDB [test]> select * from Teacher where teaId > 3;
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     4 | li           |   40 | M    | 2147483647 |
|     5 | zhao         |   50 | F    | 2147483647 |
|     5 | zhao         |   50 | F    | 1821113120 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
|   102 | zhangsan     |   30 | NULL |       NULL |
+-------+--------------+------+------+------------+
5 rows in set (0.00 sec)

MariaDB [test]> select * from Teacher where teaId in(1,4,101);
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     1 | feng         |   20 | NULL |  188188188 |
|     4 | li           |   40 | M    | 2147483647 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
+-------+--------------+------+------+------------+
3 rows in set (0.01 sec)



MariaDB [test]> select * from Teacher where teaId like ('%1%');  
+-------+--------------+------+------+-----------+
| teaId | teaname      | age  | sex  | phone     |
+-------+--------------+------+------+-----------+
|     1 | feng         |   20 | NULL | 188188188 |
|   101 | fengxiaoqing |   20 | NULL |      NULL |
|   102 | zhangsan     |   30 | NULL |      NULL |
+-------+--------------+------+------+-----------+
3 rows in set (0.00 sec)

MariaDB [test]> 

MariaDB [test]>

 

查詢重複數據：

select *  from Teacher  group by teaname having count(*) >1;

測試結果：

MariaDB [test]> select * from Teacher;
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     1 | feng         |   20 | NULL |  188188188 |
|     2 | wang         |   20 | M    | 2147483647 |
|     2 | wang         |   20 | M    | 2147483647 |
|     3 | zhang        |   30 | M    | 2147483647 |
|     4 | li           |   40 | M    | 2147483647 |
|     5 | zhao         |   50 | F    | 2147483647 |
|     5 | zhao         |   50 | F    | 1821113120 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
|   102 | zhangsan     |   30 | NULL |       NULL |
+-------+--------------+------+------+------------+
9 rows in set (0.01 sec)

MariaDB [test]> select *  from Teacher  group by teaname having count(*) >1;
+-------+---------+------+------+------------+
| teaId | teaname | age  | sex  | phone      |
+-------+---------+------+------+------------+
|     2 | wang    |   20 | M    | 2147483647 |
|     5 | zhao    |   50 | F    | 2147483647 |
+-------+---------+------+------+------------+
2 rows in set (0.00 sec)

MariaDB [test]>

聯合查詢：

select * from a,c where a.id = c.組id

查看錶結構：

show create Teacher\G;
desc Teacher;

測試結果 ：

MariaDB [test]> show create table Teacher \G;
*************************** 1. row ***************************
       Table: Teacher
Create Table: CREATE TABLE `Teacher` (
  `teaId` int(11) NOT NULL,
  `teaname` varchar(100) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `sex` enum('M','F') DEFAULT NULL,
  `phone` int(11) DEFAULT NULL,
  KEY `test_Teacher_teaId_teaname` (`teaId`,`teaname`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

ERROR: No query specified

MariaDB [test]>

MariaDB [test]> desc Teacher;
+---------+---------------+------+-----+---------+-------+
| Field   | Type          | Null | Key | Default | Extra |
+---------+---------------+------+-----+---------+-------+
| teaId   | int(11)       | NO   | MUL | NULL    |       |
| teaname | varchar(100)  | YES  |     | NULL    |       |
| age     | int(11)       | YES  |     | NULL    |       |
| sex     | enum('M','F') | YES  |     | NULL    |       |
| phone   | int(11)       | YES  |     | NULL    |       |
+---------+---------------+------+-----+---------+-------+
5 rows in set (0.01 sec)

MariaDB [test]>

5.刪除數據：

delete from Teacher where teaid='103'  #刪除指定id數據
truncate Teacher1;   #清空數據
drop table Teacher1;   #刪除表

測試結果：

delete:刪除表中指定數據條目

MariaDB [test]> delete from Teacher where teaid='103';
Query OK, 1 row affected (0.02 sec)

MariaDB [test]> select * from Teacher;
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     1 | feng         |   20 | NULL |       NULL |
|     2 | wang         |   20 | M    | 2147483647 |
|     2 | wang         |   20 | M    | 2147483647 |
|     3 | zhang        |   30 | M    | 2147483647 |
|     4 | li           |   40 | M    | 2147483647 |
|     5 | zhao         |   50 | F    | 2147483647 |
|     5 | zhao         |   50 | F    | 1821113120 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
|   102 | zhangsan     |   30 | NULL |       NULL |
+-------+--------------+------+------+------------+
9 rows in set (0.00 sec)

MariaDB [test]>

truncate: 清空表數據，表結構保留

MariaDB [test]> select * from Teacher1;
+-------+---------------+------+------+-------+
| teaId | teaname       | age  | sex  | phone |
+-------+---------------+------+------+-------+
|   101 | fengxiaoqing  |   20 | NULL |  NULL |
|   102 | zhangsan      |   30 | NULL |  NULL |
|   103 | wangwu        |   40 | NULL |  NULL |
|   104 | fengxiaoqing1 |   20 | NULL |  NULL |
|   105 | zhangsan2     |   30 | NULL |  NULL |
|   106 | wangwu3       |   40 | NULL |  NULL |
|   107 | fengxiaoqing4 |   20 | NULL |  NULL |
|   108 | zhangsan5     |   30 | NULL |  NULL |
|   109 | wangwu6       |   40 | NULL |  NULL |
|   110 | fengxiaoqing7 |   20 | NULL |  NULL |
|   111 | zhangsan8     |   30 | NULL |  NULL |
|   112 | wangwu9       |   40 | NULL |  NULL |
+-------+---------------+------+------+-------+
12 rows in set (0.00 sec)

MariaDB [test]> truncate Teacher1;
Query OK, 0 rows affected (0.02 sec)

MariaDB [test]> select * from Teacher1;
Empty set (0.00 sec)

MariaDB [test]>

drop: 刪除整個表

MariaDB [test]> drop table Teacher1;
Query OK, 0 rows affected (0.01 sec)

MariaDB [test]> show tables;
+----------------+
| Tables_in_test |
+----------------+
| Teacher        |
+----------------+
1 row in set (0.00 sec)

MariaDB [test]>

6.更新數據 

update Teacher set  phone=188188188  where teaId=1;

測試結果：

MariaDB [test]> select * from Teacher;
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     1 | feng         |   20 | NULL |       NULL |
|     2 | wang         |   20 | M    | 2147483647 |
|     2 | wang         |   20 | M    | 2147483647 |
|     3 | zhang        |   30 | M    | 2147483647 |
|     4 | li           |   40 | M    | 2147483647 |
|     5 | zhao         |   50 | F    | 2147483647 |
|     5 | zhao         |   50 | F    | 1821113120 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
|   102 | zhangsan     |   30 | NULL |       NULL |
+-------+--------------+------+------+------------+
9 rows in set (0.01 sec)


MariaDB [test]> update Teacher set  phone=188188188 where teaId=1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

MariaDB [test]> select * from Teacher;
+-------+--------------+------+------+------------+
| teaId | teaname      | age  | sex  | phone      |
+-------+--------------+------+------+------------+
|     1 | feng         |   20 | NULL |  188188188 |
|     2 | wang         |   20 | M    | 2147483647 |
|     2 | wang         |   20 | M    | 2147483647 |
|     3 | zhang        |   30 | M    | 2147483647 |
|     4 | li           |   40 | M    | 2147483647 |
|     5 | zhao         |   50 | F    | 2147483647 |
|     5 | zhao         |   50 | F    | 1821113120 |
|   101 | fengxiaoqing |   20 | NULL |       NULL |
|   102 | zhangsan     |   30 | NULL |       NULL |
+-------+--------------+------+------+------------+
9 rows in set (0.00 sec)

MariaDB [test]>

7.建立索引：

create index 庫名_表名_列名1_列名2  （列名1，列名2）;
create index test_Teacher_teaId_teaname (teaId,teaname);

查看錶有無索引：

MariaDB [test]> show index from Teacher;
Empty set (0.01 sec)

建立索引：

MariaDB [test]> show index from Teacher;   #查看
Empty set (0.01 sec)

MariaDB [test]> alter table Teacher add index test_Teacher_teaId_teaname (teaId,teaname);   #建立索引
Query OK, 0 rows affected (0.34 sec)
Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> show index from Teacher;   #再查看，索引就會建立成功
+---------+------------+----------------------------+--------------+-------------+-----------+-------------+-----
-----+--------+------+------------+---------+---------------+| Table   | Non_unique | Key_name                   | Seq_in_index | Column_name | Collation | Cardinality | Sub_
part | Packed | Null | Index_type | Comment | Index_comment |+---------+------------+----------------------------+--------------+-------------+-----------+-------------+-----
-----+--------+------+------------+---------+---------------+| Teacher |          1 | test_Teacher_teaId_teaname |            1 | teaId       | A         |           9 |     
NULL | NULL   |      | BTREE      |         |               || Teacher |          1 | test_Teacher_teaId_teaname |            2 | teaname     | A         |           9 |     
NULL | NULL   | YES  | BTREE      |         |               |+---------+------------+----------------------------+--------------+-------------+-----------+-------------+-----
-----+--------+------+------------+---------+---------------+2 rows in set (0.00 sec)

MariaDB [test]>

查看是否走索引：

explain select * from Teacher where teaname = 'feng';
MariaDB [test]> explain select * from Teacher where teaname = 'feng';
+------+-------------+---------+------+---------------+------+---------+------+------+-------------+
| id   | select_type | table   | type | possible_keys | key  | key_len | ref  | rows | Extra       |
+------+-------------+---------+------+---------------+------+---------+------+------+-------------+
|    1 | SIMPLE      | Teacher | ALL  | NULL          | NULL | NULL    | NULL |    9 | Using where |
+------+-------------+---------+------+---------------+------+---------+------+------+-------------+
1 row in set (0.00 sec)

MariaDB [test]> explain select * from Teacher where teaname = 'feng' and teaId = 1;
+------+-------------+---------+------+----------------------------+----------------------------+---------+------
-------+------+-----------------------+| id   | select_type | table   | type | possible_keys              | key                        | key_len | ref  
       | rows | Extra                 |+------+-------------+---------+------+----------------------------+----------------------------+---------+------
-------+------+-----------------------+|    1 | SIMPLE      | Teacher | ref  | test_Teacher_teaId_teaname | test_Teacher_teaId_teaname | 107     | const
,const |    1 | Using index condition |+------+-------------+---------+------+----------------------------+----------------------------+---------+------
-------+------+-----------------------+1 row in set (0.01 sec)

MariaDB [test]> 
MariaDB [test]> select * from Teacher where teaname = 'feng' and teaId = 1;
+-------+---------+------+------+-----------+
| teaId | teaname | age  | sex  | phone     |
+-------+---------+------+------+-----------+
|     1 | feng    |   20 | NULL | 188188188 |
+-------+---------+------+------+-----------+
1 row in set (0.01 sec)

MariaDB [test]>
相關文章
相關標籤/搜索
每日一句
    每一个你不满意的现在，都有一个你没有努力的曾经。
本站公眾號
   歡迎關注本站公眾號,獲取更多信息
聯繫我們 最近搜索 最新文章 沪ICP备13005482号-10 MyBatis教程 SQL 教程 MySQL教程 Java 教程 Thymeleaf 教程 Hibernate教程 Spring教程 Redis教程