Create Table create table table name mysql> create database company; Query OK, 1 row affected (0.00 sec) mysql> use company; Database changed mysql> create table if not exists t_dept( -> deptno int, -> dname varchar(20), -> loc varchar(40)); Query OK, 0 rows affected (0.20 sec) mysql> show tables; +-------------------+ | Tables_in_company | +-------------------+ | t_dept | +-------------------+ 1 row in set (0.00 sec) mysql> Display all tables in the current database mysql> show tables; +-------------------+ | Tables_in_company | +-------------------+ | t_dept | +-------------------+ 1 row in set (0.00 sec) View the structure of the table Abbreviation desc table name mysql> describe t_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 3 rows in set (0.00 sec) mysql> desc t_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 3 rows in set (0.00 sec) View table details mysql> show create table t_dept; +--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table | +--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | t_dept | CREATE TABLE `t_dept` ( `deptno` int(11) DEFAULT NULL, `dname` varchar(20) DEFAULT NULL, `loc` varchar(40) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8 | +--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) show create table t_dept \G mysql> show create table t_dept \G *************************** 1. row *************************** Table: t_dept Create Table: CREATE TABLE `t_dept` ( `deptno` int(11) DEFAULT NULL, `dname` varchar(20) DEFAULT NULL, `loc` varchar(40) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8 1 row in set (0.00 sec) Delete a table drop table table name mysql> drop table if exists t_dept; Query OK, 0 rows affected (0.12 sec) mysql> show tables; Empty set (0.00 sec) Modify table name ALTER TABLE old_table_name RENAME [TO] new_table_name mysql> alter table t_dept rename tab_dept; Query OK, 0 rows affected (0.09 sec) mysql> show tables; +-------------------+ | Tables_in_company | +-------------------+ | tab_dept | +-------------------+ 1 row in set (0.00 sec) mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 3 rows in set (0.00 sec) Add a field to the table by default at the end Add a field descri varchar(20) for tab_dept mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 3 rows in set (0.00 sec) mysql> alter table tab_dept add description varchar(20); Query OK, 0 rows affected (0.33 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | varchar(20) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec) Add a field to the first position of the table mysql> alter table tab_dept add id int first; Query OK, 0 rows affected (0.38 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | varchar(20) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) Add a field after the specified field in the table ALTER TABLE table_name ADD attribute name attribute type AFTER attribute name mysql> alter table tab_dept add comm varchar(20) after dname; Query OK, 0 rows affected (0.31 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | comm | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | varchar(20) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 6 rows in set (0.00 sec) Delete a field ALTER TABLE table_name DROP attribute_name mysql> alter table tab_dept drop comm; Query OK, 0 rows affected (0.32 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | varchar(20) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) Field modification - modify field data type mysql> alter table tab_dept modify description int; Query OK, 0 rows affected (0.45 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) Field modification - modify field name ALTER TABLE table_name CHANGE old attribute name new attribute name old data type mysql> alter table tab_dept change id deptid int; Query OK, 0 rows affected (0.07 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptid | int(11) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) Field modification - modify field name and data type at the same time ALTER TABLE table_name CHANGE old attribute name new attribute name new data type mysql> alter table tab_dept change deptid id varchar(32); Query OK, 0 rows affected (0.49 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | varchar(32) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) Modify the order 2 attributes must exist. Move deptno to the first position. mysql> alter table tab_dept modify deptno int first; Query OK, 0 rows affected (0.33 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | id | varchar(32) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) Put the ID at the end mysql> alter table tab_dept modify deptno int after descri; Query OK, 0 rows affected (0.29 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | varchar(32) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | int(11) | YES | | NULL | | | deptno | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) mysql> alter table tab_dept modify deptno int first; Query OK, 0 rows affected (0.34 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> alter table tab_dept modify id int after description; Query OK, 0 rows affected (0.47 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc tab_dept; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | deptno | int(11) | YES | | NULL | | | dname | varchar(20) | YES | | NULL | | | loc | varchar(40) | YES | | NULL | | | descri | int(11) | YES | | NULL | | | id | int(11) | YES | | NULL | | +--------+-------------+------+-----+---------+-------+ 5 rows in set (0.00 sec) You may also be interested in:
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