Drop all tables command

Question

What is the command to drop all tables in SQLite?

Similarly I\'d like to drop all indexes.

Answer 1

Once you've dropped all the tables (and the indexes will disappear when the table goes) then there's nothing left in a SQLite database as far as I know, although the file doesn't seem to shrink (from a quick test I just did).

So deleting the file would seem to be fastest - it should just be recreated when your app tries to access the db file.

Answer 2

I had this issue in Android and I wrote a method similar to it-west.

Because I used AUTOINCREMENT primary keys in my tables, there was a table called sqlite_sequence. SQLite would crash when the routine tried to drop that table. I couldn't catch the exception either. Looking at https://www.sqlite.org/fileformat.html#internal_schema_objects, I learned that there could be several of these internal schema tables that I didn't want to drop. The documentation says that any of these tables have names beginning with sqlite_ so I wrote this method

private void dropAllUserTables(SQLiteDatabase db) {
    Cursor cursor = db.rawQuery("SELECT name FROM sqlite_master WHERE type='table'", null);
    //noinspection TryFinallyCanBeTryWithResources not available with API < 19
    try {
        List<String> tables = new ArrayList<>(cursor.getCount());

        while (cursor.moveToNext()) {
            tables.add(cursor.getString(0));
        }

        for (String table : tables) {
            if (table.startsWith("sqlite_")) {
                continue;
            }
            db.execSQL("DROP TABLE IF EXISTS " + table);
            Log.v(LOG_TAG, "Dropped table " + table);
        }
    } finally {
        cursor.close();
    }
}

Answer 3

I can't say this is the most bulletproof or portable solution, but it works for my testing scripts:

.output /tmp/temp_drop_tables.sql
select 'drop table ' || name || ';' from sqlite_master where type = 'table';
.output stdout
.read /tmp/temp_drop_tables.sql
.system rm /tmp/temp_drop_tables.sql

This bit of code redirects output to a temporary file, constructs the 'drop table' commands that I want to run (sending the commands to the temp file), sets output back to standard out, then executes the commands from the file, and finally removes the file.

Answer 4

While it is true that there is no DROP ALL TABLES command you can use the following set of commands.

Note: These commands have the potential to corrupt your database, so make sure you have a backup

PRAGMA writable_schema = 1;
delete from sqlite_master where type in ('table', 'index', 'trigger');
PRAGMA writable_schema = 0;

you then want to recover the deleted space with

VACUUM;

and a good test to make sure everything is ok

PRAGMA INTEGRITY_CHECK;

Answer 5

I'd like to add to other answers involving dropping tables and not deleting the file, that you can also execute delete from sqlite_sequence to reset auto-increment sequences.

Answer 6

Using pysqlite:

tables = list(cur.execute("select name from sqlite_master where type is 'table'"))

cur.executescript(';'.join(["drop table if exists %s" %i for i in tables]))