Changes

Each database table must contain one or more columns that can be used to identify each row in the table uniquely. This is known in database terminology as the Primary Key. For example, a table may use a bank account number column as the primary key. Alternatively, a customer table may use the customer's social security number as the primary key.

Primary keys allow the database management system to identify a specific row in a table uniquely. Without a primary key it would not be possible to retrieve or delete a specific row in a table because there can be no certainty that the correct row has been selected. For example, suppose a table existed where the customer's last name had been defined as the primary key. Imagine then the problem that might arise if more than one customer named "Smith" were recorded in the database. Without some guaranteed way to identify a specific row uniquely, it would be impossible to ensure the correct data was being accessed at any given time.

/data/data/<package name>/databases/<database filename>.db

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For example, if an application with the package name com.example.MyDBApp creates a database named mydatabase.db, the path to the file on the device would read as follows:

sqlite> .exit

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When running an Android application in the emulator environment, any database files will be created on the file system of the emulator using the previously discussed path convention. This has the advantage that you can connect with adb, navigate to the location of the database file, load it into the sqlite3 interactive tool and perform tasks on the data to identify possible problems occurring in the application code.

* '''execSQL()''' – Executes a single SQL statement that does not return result data.

* '''rawQuery()''' – Executes an SQL query statement and returns matching results in the form of a Cursor object.

=== SQLiteOpenHelper ===