SQLite Database in Android:

SQLite is a lightweight, embedded relational database management system that is widely used in Android applications to store and manage structured data. It's a part of the Android framework and provides a local storage solution for apps to store data locally on the device.

Key Concepts:

Database: A structured collection of data organized into tables, rows, and columns. Table: Represents a single type of data entity. It consists of rows (records) and columns (fields) Row: A single record within a table, containing values for each column. Column: Represents a specific attribute or property of the data stored in the table.

#Using SQLite Database in Android: To use an SQLite database in your Android application, follow these steps:

Create a Database Helper: Extend the SQLiteOpenHelper class to manage database creation and version management. Override the onCreate and onUpgrade methods.

Define Database Schema: Define the tables and their columns in a contract class that extends BaseColumns.

Perform Database Operations:

Insert: Use SQLiteDatabase.insert() or SQLiteDatabase.insertOrThrow() to add data to a table. Query: Use SQLiteDatabase.query() to retrieve data from a table. Update: Use SQLiteDatabase.update() to modify existing records. Delete: Use SQLiteDatabase.delete() to remove records from a table. Close the Database: Always close the database connection when you're done with it using SQLiteDatabase.close().

#Example: Here's a simplified example of creating an SQLite database to store and retrieve user data:

#Database Helper:

public class MyDatabaseHelper extends SQLiteOpenHelper { private static final String DATABASE_NAME = "my_app.db"; private static final int DATABASE_VERSION = 1;

public MyDatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(UserContract.UserEntry.SQL_CREATE_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL(UserContract.UserEntry.SQL_DELETE_TABLE);
    onCreate(db);
}

}

#Database Schema:

public class UserContract { private UserContract() {}

public static class UserEntry implements BaseColumns {
    public static final String TABLE_NAME = "users";
    public static final String COLUMN_NAME_USERNAME = "username";
    public static final String COLUMN_NAME_EMAIL = "email";

    public static final String SQL_CREATE_TABLE =
        "CREATE TABLE " + TABLE_NAME + " (" +
        _ID + " INTEGER PRIMARY KEY," +
        COLUMN_NAME_USERNAME + " TEXT," +
        COLUMN_NAME_EMAIL + " TEXT)";

    public static final String SQL_DELETE_TABLE =
        "DROP TABLE IF EXISTS " + TABLE_NAME;
}

}

#Perform Database Operations:

// Insert SQLiteDatabase db = myDatabaseHelper.getWritableDatabase(); ContentValues values = new ContentValues(); values.put(UserContract.UserEntry.COLUMN_NAME_USERNAME, "user123"); values.put(UserContract.UserEntry.COLUMN_NAME_EMAIL, "user@example.com"); long newRowId = db.insert(UserContract.UserEntry.TABLE_NAME, null, values);

// Query String[] projection = { UserContract.UserEntry._ID, UserContract.UserEntry.COLUMN_NAME_USERNAME, UserContract.UserEntry.COLUMN_NAME_EMAIL }; Cursor cursor = db.query( UserContract.UserEntry.TABLE_NAME, projection, null, null, null, null, null );

// Don't forget to close the cursor and database when done cursor.close(); db.close();