USE db_name

The USE statement tells MySQL to use the named database as the default (current) database for subsequent statements. This statement requires some privilege for the database or some object within it.

The named database remains the default until the end of the session or another USE statement is issued:

USE db1;
SELECT COUNT(*) FROM mytable;   # selects from db1.mytable
USE db2;
SELECT COUNT(*) FROM mytable;   # selects from db2.mytable

The database name must be specified on a single line. Newlines in database names are not supported.

Making a particular database the default by means of the USE statement does not preclude accessing tables in other databases. The following example accesses the author table from the db1 database and the editor table from the db2 database:

USE db1;
SELECT author_name,editor_name FROM author,db2.editor
  WHERE author.editor_id = db2.editor.editor_id;