How to add, modify, and delete fields in mysql _ MySQL
Source: Internet
Author: User
How to add, modify, and delete fields in mysql alter 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 a column
Alter table t2 drop column c;
// Rename a column
Alter table t1 change a B integer;
// Change the column type
Alter table t1 change B bigint not null;
Alter table infos change list tinyint not null default '0 ';
// Rename the table
Alter table t1 rename t2;
Add index
Mysql> alter table tablename change depno int (5) not null;
Mysql> alter table tablename add index name (field name 1 [, field name 2…]);
Mysql> alter table tablename add index emp_name (name );
Index with primary keywords
Mysql> alter table tablename add primary key (id );
Add an index with unique conditions
Mysql> alter table tablename add unique emp_name2 (cardnumber );
Delete an index
Mysql> alter table tablename drop index emp_name;
Modify table:
Add a field to www.3ppt.com:
Mysql> alter table table_name add field_name field_type;
Modify the original field name and type:
Mysql> alter table table_name change old_field_name new_field_name field_type;
Delete field:
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