The following article describes how to add, delete, and modify fields and adjust the order of fields in MySQL, the following describes how to add, delete, and modify fields and adjust the order of fields in MySQL.
MySQL changes the table structure to add fields:
- Alter table 'user _ movement_log'
- Add column GatewayId int not null default 0 AFTER 'regionid' (AFTER which field is added)
MySQL changes the table structure to delete fields:
- alter table `user_movement_log` drop column Gatewayid
MySQL changes the table structure to adjust the field sequence:
- ALTER TABLE `user_movement_log` CHANGE `GatewayId` `GatewayId` int not null default 0 AFTER RegionID
Primary Key
Al
- ter table tabelname add new_field_id int(5) unsigned default 0 not null auto_increment ,add primary key (new_field_id);
Add a new column
- alter table t2 add d timestamp;
- alter table infos add ex tinyint not null default ‘0′;
Delete column
- alter table t2 drop column c;
Rename a column
- alter table t1 change a b integer;
Change column type
- alter table t1 change b b bigint not null;
- alter table infos change list list tinyint not null default ‘0′;
Rename a table
- alter table t1 rename t2;
Add Index
- > Alter table tablename change depno int (5) not null;
- > Alter table tablename add index name (field name 1 [, field name 2…]);
- > Alter table tablename add index emp_name (name );
MySQL changes the index of the primary keyword in the Table Structure
- > alter table tablename add primary key(id);
Add an index with unique conditions
- > alter table tablename add unique emp_name2(cardnumber);
Delete An index
- >alter table tablename drop index emp_name;
Modify Table:
Add field:
- > ALTER TABLE table_name ADD field_name field_type;
Modify the original field name and type:
- > ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;
Delete field:
- > ALTER TABLE table_name DROP field_name;
The above content introduces how to change the table structure, add, delete, modify fields, and adjust the order of fields in MySQL. I hope you will get some benefits.