Sql – How to list the tables in a SQLite database file that was opened with ATTACH

databasemetadatasqlsqlite

What SQL can be used to list the tables, and the rows within those tables in an SQLite database file – once I have attached it with the ATTACH command on the SQLite 3 command line tool?

Best Solution

There are a few steps to see the tables in an SQLite database:

List the tables in your database:
```
.tables
```
List how the table looks:
```
.schema tablename
```
Print the entire table:
```
SELECT * FROM tablename;
```
List all of the available SQLite prompt commands:
```
.help
```

Related Solutions

Sqlite – How to check in SQLite whether a table exists

I missed that FAQ entry.

Anyway, for future reference, the complete query is:

SELECT name FROM sqlite_master WHERE type='table' AND name='{table_name}';

Where {table_name} is the name of the table to check.

Documentation section for reference: Database File Format. 2.6. Storage Of The SQL Database Schema

This will return a list of tables with the name specified; that is, the cursor will have a count of 0 (does not exist) or a count of 1 (does exist)

Sql – Is it possible to insert multiple rows at a time in an SQLite database

update

As BrianCampbell points out here, SQLite 3.7.11 and above now supports the simpler syntax of the original post. However, the approach shown is still appropriate if you want maximum compatibility across legacy databases.

original answer

If I had privileges, I would bump river's reply: You can insert multiple rows in SQLite, you just need different syntax. To make it perfectly clear, the OPs MySQL example:

INSERT INTO 'tablename' ('column1', 'column2') VALUES
  ('data1', 'data2'),
  ('data1', 'data2'),
  ('data1', 'data2'),
  ('data1', 'data2');

This can be recast into SQLite as:

     INSERT INTO 'tablename'
          SELECT 'data1' AS 'column1', 'data2' AS 'column2'
UNION ALL SELECT 'data1', 'data2'
UNION ALL SELECT 'data1', 'data2'
UNION ALL SELECT 'data1', 'data2'

a note on performance

I originally used this technique to efficiently load large datasets from Ruby on Rails. However, as Jaime Cook points out, it's not clear this is any faster wrapping individual INSERTs within a single transaction:

BEGIN TRANSACTION;
INSERT INTO 'tablename' table VALUES ('data1', 'data2');
INSERT INTO 'tablename' table VALUES ('data3', 'data4');
...
COMMIT;

If efficiency is your goal, you should try this first.

a note on UNION vs UNION ALL

As several people commented, if you use UNION ALL (as shown above), all rows will be inserted, so in this case, you'd get four rows of data1, data2. If you omit the ALL, then duplicate rows will be eliminated (and the operation will presumably be a bit slower). We're using UNION ALL since it more closely matches the semantics of the original post.

in closing

P.S.: Please +1 river's reply, as it presented the solution first.