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1. Overview


ATTACH DATABASE expr AS schema-name


R-35371-58843:[The ATTACH DATABASE statement adds another database file to the current database connection. ] Database files that were previously attached can be removed using the DETACH DATABASE command.

2. Details

R-02612-37947:[The filename for the database to be attached is the value of the expression that occurs before the AS keyword. ] R-57724-31954:[The filename of the database follows the same semantics as the filename argument to sqlite3_open() and sqlite3_open_v2(); the special name ":memory:" results in an in-memory database and an empty string results in a new temporary database. ] R-00402-11496:[The filename argument can be a URI filename if URI filename processing is enable on the database connection. ] The default behavior is for URI filenames to be disabled, however that might change in a future release of SQLite, so application developers are advised to plan accordingly.

The name that occurs after the AS keyword is the name of the database used internally by SQLite. R-40602-24566:[The schema-names 'main' and 'temp' refer to the main database and the database used for temporary tables. ] R-43455-30330:[The main and temp databases cannot be attached or detached. ]

R-04549-59621:[Tables in an attached database can be referred to using the syntax schema-name.table-name. ] R-38412-06710:[If the name of the table is unique across all attached databases and the main and temp databases, then the schema-name prefix is not required. ] R-55636-16561:[If two or more tables in different databases have the same name and the schema-name prefix is not used on a table reference, then the table chosen is the one in the database that was least recently attached. ]

R-10872-35808:[Transactions involving multiple attached databases are atomic, assuming that the main database is not ":memory:" and the journal_mode is not WAL. ] R-34979-54336:[If the main database is ":memory:" or if the journal_mode is WAL, then transactions continue to be atomic within each individual database file. But if the host computer crashes in the middle of a COMMIT where two or more database files are updated, some of those files might get the changes where others might not. ]

R-06367-56981:[There is a limit, set using sqlite3_limit() and SQLITE_LIMIT_ATTACHED, to the number of databases that can be simultaneously attached to a single database connection. ]

This page last modified on 2022-01-08 05:02:57 UTC