MySQL commonly used command learning

Others 2021-03-30 22:47:39 views: null

Some things, even though they have been read thousands of times, but as long as they are not recorded in my own notebook, I feel a little flustered in my heart for some reason!

Common database operations

Create database

mysql> create database test_db;
Query OK, 1 row affected (0.00 sec)

Delete database

mysql> drop database test_db;
Query OK, 0 rows affected (0.03 sec)

Select database

mysql> use test_db;
Database changed

Data sheet common operations

Create data table

mysql> CREATE TABLE IF NOT EXISTS `runoob_tbl`(
    ->    `runoob_id` INT UNSIGNED AUTO_INCREMENT,
    ->    `runoob_title` VARCHAR(100) NOT NULL,
    ->    `runoob_author` VARCHAR(40) NOT NULL,
    ->    `submission_date` DATE,
    ->    PRIMARY KEY ( `runoob_id` )
    -> );
Query OK, 0 rows affected (0.01 sec)

# 如果数据库有中文的话最好还是设置字符集编码。
mysql> CREATE TABLE IF NOT EXISTS `runoob_tbl`(
    ->    `runoob_id` INT UNSIGNED AUTO_INCREMENT,
    ->    `runoob_title` VARCHAR(100) NOT NULL,
    ->    `runoob_author` VARCHAR(40) NOT NULL,
    ->    `submission_date` DATE,
    ->    PRIMARY KEY ( `runoob_id` )
    -> )ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.01 sec)

Delete data table

mysql> drop table runoob_tbl;
Query OK, 0 rows affected (0.02 sec)

Insert data

mysql> INSERT INTO runoob_tbl
    -> (runoob_title, runoob_author, submission_date)
    -> VALUES
    -> ("学习 PHP", "菜鸟教程", NOW());

(runoob_title, runoob_author, submission_date)
VALUES
("JAVA 教程", "RUNOOB.COM", '2016-05-06');Query OK, 1 row affected, 1 warning (0.00 sec)

mysql> INSERT INTO runoob_tbl
    -> (runoob_title, runoob_author, submission_date)
    -> VALUES
    -> ("学习 MySQL", "菜鸟教程", NOW());
Query OK, 1 row affected, 1 warning (0.00 sec)

mysql> INSERT INTO runoob_tbl
    -> (runoob_title, runoob_author, submission_date)
    -> VALUES
    -> ("JAVA 教程", "RUNOOB.COM", '2016-05-06');
Query OK, 1 row affected (0.00 sec)

mysql> select * from runoob_tbl;
+-----------+--------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+--------------+---------------+-----------------+
|         1 | 学习 PHP     | 菜鸟教程      | 2020-12-09      |
|         2 | 学习 MySQL   | 菜鸟教程      | 2020-12-09      |
|         3 | JAVA 教程    | RUNOOB.COM   | 2016-05-06      |
+-----------+--------------+---------------+-----------------+
3 rows in set (0.00 sec)

Query data

SELECT column_name,column_name FROM table_name [WHERE Clause] [LIMIT N][ OFFSET M]
mysql> SELECT runoob_id, runoob_title, runoob_author, submission_date FROM runoob_tbl;
+-----------+--------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+--------------+---------------+-----------------+
|         1 | 学习 PHP     | 菜鸟教程      | 2020-12-09      |
|         2 | 学习 MySQL   | 菜鸟教程      | 2020-12-09      |
|         3 | JAVA 教程    | RUNOOB.COM    | 2016-05-06      |
+-----------+--------------+---------------+-----------------+
3 rows in set (0.00 sec)

WHERE statement

SELECT field1, field2,...fieldN FROM table_name1, table_name2... [WHERE condition1 [AND [OR]] condition2.....
mysql> SELECT * from runoob_tbl WHERE runoob_author='RUNOOB.COM';
+-----------+--------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+--------------+---------------+-----------------+
|         3 | JAVA 教程    | RUNOOB.COM    | 2016-05-06      |
+-----------+--------------+---------------+-----------------+
1 row in set (0.00 sec)

UPDATE statement

UPDATE table_name SET field1=new-value1, field2=new-value2 [WHERE Clause]
mysql> UPDATE runoob_tbl SET runoob_title='学习 C++' WHERE runoob_id=3;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

DELETE statement

DELETE FROM table_name [WHERE Clause]
mysql> DELETE FROM runoob_tbl WHERE runoob_id=3;
Query OK, 1 row affected (0.01 sec)

LIKE statement

SELECT field1, field2,...fieldN FROM table_name WHERE field1 LIKE condition1 [AND [OR]] filed2 = 'somevalue'
  1. %: Represents any 0 or more characters. It can match characters of any type and length. In some cases, if it is Chinese, please use two percent signs (%%) to indicate it.
  2. _: Represents any single character. Match a single arbitrary character, it is often used to limit the character length of the expression.
  3. []: Represents one of the characters listed in the brackets (similar to regular expressions). Specify a character, string, or range, and require the matched object to be any of them.
  4. [^]: Indicates a single character not included in the brackets. Its value is the same as [], but it requires that the matched object is any character other than the specified character.
mysql> SELECT * from runoob_tbl  WHERE runoob_title LIKE '%SQL';
+-----------+--------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+--------------+---------------+-----------------+
|         2 | 学习 MySQL   | 菜鸟教程      | 2020-12-09      |
+-----------+--------------+---------------+-----------------+
1 row in set (0.00 sec)

Common operations of data table fields

Modify the table name of the data table

alter table old_table rename to new_table
mysql> show tables;
+-------------------+
| Tables_in_looking |
+-------------------+
| comm_config       |
| runoob_tbl        |
| tb_person         |
| tb_person_copy    |
| test1             |
+-------------------+
5 rows in set (0.00 sec)

mysql> alter table runoob_tbl rename to runoob_tbl_new;
Query OK, 0 rows affected (0.02 sec)

mysql> show tables;
+-------------------+
| Tables_in_looking |
+-------------------+
| comm_config       |
| runoob_tbl_new    |
| tb_person         |
| tb_person_copy    |
| test1             |
+-------------------+
5 rows in set (0.00 sec)

Create a table with the same structure as the original table

create table new_table like old_table
mysql> show tables;
+-------------------+
| Tables_in_looking |
+-------------------+
| comm_config       |
| runoob_tbl_new    |
| tb_person         |
| tb_person_copy    |
| test1             |
+-------------------+
5 rows in set (0.00 sec)

mysql> create table runoob_tbl_new2 like runoob_tbl_new;
Query OK, 0 rows affected (0.01 sec)

mysql> show tables;
+-------------------+
| Tables_in_looking |
+-------------------+
| comm_config       |
| runoob_tbl_new    |
| runoob_tbl_new2   |
| tb_person         |
| tb_person_copy    |
| test1             |
+-------------------+
6 rows in set (0.00 sec)

Add a field to the specified position of the table

alter table test_tb add i int after runoob_id

If there is no keyword such as after, it will be added at the end by default.

mysql> desc test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
4 rows in set (0.01 sec)

mysql> alter table test_tb add i int after runoob_id;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| i               | int(11)          | YES  |     | NULL    |                |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
mysql> desc test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

mysql> alter table test_tb add i int;
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
| i               | int(11)          | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)

Delete table field

alter table test_tb drop i
mysql> show columns from test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| i               | int(11)          | YES  |     | NULL    |                |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)

mysql> alter table test_tb drop i;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

Modify field type and name

alter table test_tb change runoob_id id int
mysql> desc test_tb;
+-----------------+------------------+------+-----+---------+----------------+
| Field           | Type             | Null | Key | Default | Extra          |
+-----------------+------------------+------+-----+---------+----------------+
| runoob_id       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| runoob_title    | varchar(100)     | NO   |     | NULL    |                |
| runoob_author   | varchar(40)      | NO   |     | NULL    |                |
| submission_date | date             | YES  |     | NULL    |                |
+-----------------+------------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)

mysql> alter table test_tb change runoob_id id int;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc test_tb;
+-----------------+--------------+------+-----+---------+-------+
| Field           | Type         | Null | Key | Default | Extra |
+-----------------+--------------+------+-----+---------+-------+
| id              | int(11)      | NO   | PRI | NULL    |       |
| runoob_title    | varchar(100) | NO   |     | NULL    |       |
| runoob_author   | varchar(40)  | NO   |     | NULL    |       |
| submission_date | date         | YES  |     | NULL    |       |
+-----------------+--------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

Modify field default value

ALTER TABLE tableName MODIFY j BIGINT NOT NULL DEFAULT 100

ALTER TABLE tableName ALTER i SET DEFAULT 1000

Delete field foreign key constraints

alter table tableName drop foreign key keyName

Copy of data table

Get the complete structure of the data table

mysql> show create table test_tb \G;
*************************** 1. row ***************************
       Table: test_tb
Create Table: CREATE TABLE `test_tb` (
  `id` int(11) NOT NULL,
  `runoob_title` varchar(100) NOT NULL,
  `runoob_author` varchar(40) NOT NULL,
  `submission_date` date DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

ERROR: 
No query specified

CREATE TABLE targetTable LIKE sourceTable;
INSERT INTO targetTable SELECT * FROM sourceTable;

Copy table structure and data

create table targetTable select * from sourceTable
mysql> create table new_table select * from runoob_tbl_new;
Query OK, 2 rows affected (0.01 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql> select * from new_table;
+-----------+--------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+--------------+---------------+-----------------+
|         1 | 学习 PHP     | 菜鸟教程      | 2020-12-09      |
|         2 | 学习 MySQL   | 菜鸟教程      | 2020-12-09      |
+-----------+--------------+---------------+-----------------+
2 rows in set (0.00 sec)

Copy table structure

create table targetTable select * from sourceTable where 1=2
mysql> create table new_table2 select * from runoob_tbl_new where 1=2;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> create table new_table3 like runoob_tbl_new;
Query OK, 0 rows affected (0.01 sec)

mysql> select * from new_table2;
Empty set (0.00 sec)

mysql> select * from new_table3;
Empty set (0.00 sec)

 

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