Using Prepared Statements in SQLite on Android

1. Create a SQLiteOpenHelper subclass:

   • This class is responsible for managing the database connection and creating/upgrading the database schema.
   • Override the onCreate() and onUpgrade() methods to define how the database should be created and updated.

2. Get a reference to the database:

3. Create a prepared statement:

   • Use the compileStatement() method on the database object to create a prepared statement. This method takes a SQL query as input.
   • Placeholders (e.g., ?) can be used in the SQL query to represent values that will be bound later.

4. Bind parameters:

5. Execute the statement:

Here's a code example:

``

import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase;
import android.database.Cursor;   

public class MyDatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "mydb.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) {
        // Create a table
        db.execSQL("CREATE TABLE mytable (id INTEGER PRIMARY KEY, name TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)    {
        // Upgrade the database schema if needed
        db.execSQL("DROP TABLE IF EXISTS mytable");
        onCreate(db);
    }

    public void insertData(String name) {
        SQLiteDatabase db = getWritableDatabase();
        SQLiteStatement stmt = db.compileStatement("INSERT INTO mytable (name) VALUES (?)");
        stmt.bindString(1, name);
        stmt.execute();
        stmt.close();
        db.close();
    }

    public Cursor queryData() {
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM mytable", null);
        return cursor;
    }
}

Key Concepts:

• Cursor: Used to iterate over query results.
• SQLiteStatement: Represents a precompiled SQL statement.
• SQLiteDatabase: Represents a database connection.
• SQLiteOpenHelper: A base class for managing SQLite databases in Android applications.
• Prepared Statements: These are precompiled SQL statements that can be executed multiple times with different parameter values, preventing SQL injection vulnerabilities and improving performance.

Code Breakdown:

Alternative Methods for Using Prepared Statements in SQLite on Android

While prepared statements are generally the preferred method for executing SQL queries in Android due to their security and performance benefits, there are alternative approaches that you might consider in certain scenarios.

Raw Queries:

• Disadvantages:
  • Increased vulnerability to SQL injection attacks if not handled carefully.
  • Potential performance overhead for frequently executed queries.
• Syntax: db.execSQL(sql);
• Direct execution: Raw queries allow you to directly execute SQL statements without using placeholders.

SQLiteQueryBuilder:

• Disadvantages:
• Advantages:
  • Can be used for more complex query scenarios.
  • Offers some level of protection against SQL injection if used correctly.
• Syntax:
  • SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
  • queryBuilder.setTables("mytable");
  • queryBuilder.appendWhere("name = ?");
  • Cursor cursor = queryBuilder.query(db, projection, null, selectionArgs, null, null, null);
• Flexible query building: SQLiteQueryBuilder provides a more flexible way to construct SQL queries, especially when you need to dynamically build queries based on various conditions.

Content Providers:

• Disadvantages:
• Advantages:
  • Encapsulates data access logic.
  • Provides a central point of control for data management.
• Syntax:
  • Uri uri = ContentUris.withAppendedId(MyContentProvider.CONTENT_URI, id);
  • Cursor cursor = getContentResolver().query(uri, projection, selection, selectionArgs, sortOrder);
• Data abstraction: Content providers provide a standardized way to access and manage data from different applications.

When to Choose Which Method:

• Content providers: Use content providers when you need to share data between applications or when you want to abstract data access logic.
• SQLiteQueryBuilder: Use this for more complex query scenarios where you need to dynamically build queries based on various conditions.
• Raw queries: Consider using raw queries for very simple and static queries where SQL injection is not a concern.
• Prepared statements: Generally the best choice for most scenarios due to their security and performance benefits.