Add, modify, delete functions in the MySQL tutorial
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 Column
ALTER TABLE T2 drop column C;
renaming columns
ALTER TABLE T1 change a b integer;
Change the type of a column
ALTER TABLE T1 change b b bigint not null;
ALTER TABLE infos change list tinyint not null default ' 0 ';
Renaming tables
ALTER TABLE t1 rename T2;
Add index
Mysql> ALTER TABLE tablename change depno depno int (5) is not null;
Mysql> ALTER TABLE tablename ADD index index name (field name 1[, field Name 2 ...]);
Mysql> ALTER TABLE tablename Add index Emp_name (name);
Index of the Primary keyword
Mysql> ALTER TABLE TableName ADD PRIMARY key (ID);
Index with unique restriction criteria
Mysql> ALTER TABLE tablename add unique emp_name2 (cardnumber);
Delete an index
Mysql>alter table tablename DROP index emp_name;
To modify a table:
Add fields:
Mysql> ALTER TABLE table_name add Field_name field_type;
To modify the original field name and type:
Mysql> ALTER TABLE table_name change old_field_name new_field_name field_type;
To delete a field:
Mysql> ALTER TABLE table_name drop FIELD_NAME;