Sqlite – Accessing SQLite database in android emulator

Assuming three columns in the table: ID, NAME, ROLE

BAD: This will insert or replace all columns with new values for ID=1:

INSERT OR REPLACE INTO Employee (id, name, role) 
  VALUES (1, 'John Foo', 'CEO');

BAD: This will insert or replace 2 of the columns... the NAME column will be set to NULL or the default value:

INSERT OR REPLACE INTO Employee (id, role) 
  VALUES (1, 'code monkey');

GOOD: Use SQLite On conflict clause UPSERT support in SQLite! UPSERT syntax was added to SQLite with version 3.24.0!

UPSERT is a special syntax addition to INSERT that causes the INSERT to behave as an UPDATE or a no-op if the INSERT would violate a uniqueness constraint. UPSERT is not standard SQL. UPSERT in SQLite follows the syntax established by PostgreSQL.

GOOD but tedious: This will update 2 of the columns. When ID=1 exists, the NAME will be unaffected. When ID=1 does not exist, the name will be the default (NULL).

INSERT OR REPLACE INTO Employee (id, role, name) 
  VALUES (  1, 
            'code monkey',
            (SELECT name FROM Employee WHERE id = 1)
          );

This will update 2 of the columns. When ID=1 exists, the ROLE will be unaffected. When ID=1 does not exist, the role will be set to 'Benchwarmer' instead of the default value.

INSERT OR REPLACE INTO Employee (id, name, role) 
  VALUES (  1, 
            'Susan Bar',
            COALESCE((SELECT role FROM Employee WHERE id = 1), 'Benchwarmer')
          );

Several tips:

1. Put inserts/updates in a transaction.
2. For older versions of SQLite - Consider a less paranoid journal mode (pragma journal_mode). There is NORMAL, and then there is OFF, which can significantly increase insert speed if you're not too worried about the database possibly getting corrupted if the OS crashes. If your application crashes the data should be fine. Note that in newer versions, the OFF/MEMORY settings are not safe for application level crashes.
3. Playing with page sizes makes a difference as well (PRAGMA page_size). Having larger page sizes can make reads and writes go a bit faster as larger pages are held in memory. Note that more memory will be used for your database.
4. If you have indices, consider calling CREATE INDEX after doing all your inserts. This is significantly faster than creating the index and then doing your inserts.
5. You have to be quite careful if you have concurrent access to SQLite, as the whole database is locked when writes are done, and although multiple readers are possible, writes will be locked out. This has been improved somewhat with the addition of a WAL in newer SQLite versions.
6. Take advantage of saving space...smaller databases go faster. For instance, if you have key value pairs, try making the key an INTEGER PRIMARY KEY if possible, which will replace the implied unique row number column in the table.
7. If you are using multiple threads, you can try using the shared page cache, which will allow loaded pages to be shared between threads, which can avoid expensive I/O calls.
8. Don't use !feof(file)!

I've also asked similar questions here and here.