MySQL: Updating a MySQL Table Structure
The structure of table can be changed with the alter
keyword. Examples in various situations follow.
Adding Columns/Fields
The syntax for adding a column follows.
alter table tablename add columnname datatype
Tablename, columnname, and datatype are supplied by you. For example:
alter table lists add title varchar(30);
The above command adds the title field/column to the table lists, and sets the datatype to varchar(30). Modifiers can also be used. The following example requires the column contains data.
alter table lists add title varchar(30);
Deleting Columns/Fields
The syntax for dropping a column or field from a table is pretty straightforward.
alter table tablename drop columnname;
You supply tablename and columnname. For example, to delete the column just added above, the syntax would be:
alter table lists drop title;
This drops the title field from the table lists.