SQLite Learning Note 3: Attaching a database and detaching a database

In front of you. If you create a database, then we need to operate the database;

But the Sqlite3 command can only operate one database at a time, what if there are multiple databases under the current path? This will require the use of additional databases.

An associated database

Attaching a database is actually telling Sqlite3 that the SQL statement you wrote is the database you are working on. How does it work?

The basic syntax is as follows:

ATTACH DATABASE ' DatabaseName ' as ' alias-name ';

the statements in *sqlite3 need to be finished in a good minute.

Using the name above, if the database exists, it will be associated to ' alias-name '; if it does not exist, the ' DataBaseName ' will be created first and then associated.

So, we can use the following command to correlate to the database we created earlier:

sqlite> ATTACH DATABASE ' mydatabase.db ' as ' TEST ';

Use the command at this time:

. Database

You can see that I see one more ' test ' database, which is associated with the same file as our mydatabase.

#此时你还可以看到一个main数据库, the main or temp database cannot be used to correlate, otherwise an error will be made: Database main/temp is already on use.

Two separate databases

Separating and attaching is a reverse process, with the following basic syntax:

DETACH DATABASE ' Databasename-name ';

#无法分离main或者temp数据库

Separating the current data has no effect on other databases attached to the file.