Add a database to the current connection
ATTACH [DATABASE] database-filename AS database-name
The ATTACH DATABASE statement adds another database file to the current database connection. If the filename contains punctuation characters, it must be placed inside quotation marks. The names main and temp refer to the main database and the database used for temporary tables. These cannot be detached. Attached databases are removed using the DETACH DATABASE statement.
You can read from and write to an attached database, and you can modify the schema of the attached database.
You cannot create a new table with the same name as a table in an attached database, but you can attach a database which contains tables whose names are duplicates of tables in the main database. It is also permissible to attach the same database file multiple times.
Tables in an attached database can be referred to using the syntax database-name.table-name. If an attached table doesn't have a duplicate table name in the main database, it doesn't require a database name prefix. When a database is attached, all of its tables which don't have duplicate names become the default table of that name. Any tables of that name attached afterwards require the table prefix. If the default table of a given name is detached, then the last table of that name attached becomes the new default.
Transactions involving multiple attached databases are atomic. There is a compile-time limit of 10 attached database files.