What are the applications and best practices of SQLite in mobile development?

SQLite has widespread applications and specific best practices in mobile development:

1. Advantages of SQLite in Mobile Development

   • Lightweight: Consumes few resources, suitable for mobile devices
   • Zero Configuration: No need to install and configure database server
   • Local Storage: Data stored locally on device, available offline
   • Cross-Platform: Supported by iOS, Android, React Native, etc.

2. Mobile Platform Integration

   swift
   // iOS (Swift) - Using SQLite
   import SQLite3
   
   let dbPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] + "/database.db"
   var db: OpaquePointer?
   
   if sqlite3_open(dbPath, &db) == SQLITE_OK {
       // Database opened successfully
   }

   kotlin
   // Android (Kotlin) - Using SQLite
   class DatabaseHelper(context: Context) : SQLiteOpenHelper(context, "database.db", null, 1) {
       override fun onCreate(db: SQLiteDatabase) {
           db.execSQL("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)")
       }
       
       override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
           db.execSQL("DROP TABLE IF EXISTS users")
           onCreate(db)
       }
   }

3. Mobile App Database Design Best Practices

   • Simplify Table Structure: Avoid over-normalization, reduce JOIN operations
   • Use Indexes: Create indexes for frequently queried fields
   • Batch Operations: Use transactions to batch insert data
   • Paginated Loading: Use LIMIT and OFFSET for paginated queries

4. Performance Optimization Tips

   swift
   // Swift - Use transactions for batch insert
   sqlite3_exec(db, "BEGIN TRANSACTION", nil, nil, nil)
   for user in users {
       let sql = "INSERT INTO users (name) VALUES ('\(user.name)')"
       sqlite3_exec(db, sql, nil, nil, nil)
   }
   sqlite3_exec(db, "COMMIT", nil, nil, nil)

   kotlin
   // Kotlin - Use prepared statements
   val stmt = db.compileStatement("INSERT INTO users (name) VALUES (?)")
   users.forEach { user ->
       stmt.clearBindings()
       stmt.bindString(1, user.name)
       stmt.executeInsert()
   }

5. Data Synchronization Strategies

   • Incremental Sync: Only sync changed data
   • Timestamp Marking: Use updated_at field to track changes
   • Conflict Resolution: Implement conflict detection and resolution mechanisms
   • Background Sync: Execute sync operations in background threads

6. Offline Support

   • Local Cache: Cache server data to local SQLite
   • Offline Queue: Store offline operations in queue, sync when online
   • Data Merging: Implement logic to merge local and server data

7. Data Security

   swift
   // iOS - Use SQLCipher encryption
   let key = "encryption_key".data(using: .utf8)
   sqlite3_key(db, key, Int32(key!.count))

   kotlin
   // Android - Use SQLCipher
   SQLiteDatabase.loadLibs(context)
   val db = SQLiteDatabase.openOrCreateDatabase(dbPath, "encryption_key", null)

8. Database Version Management

   kotlin
   // Android - Database upgrade
   override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
       if (oldVersion < 2) {
           db.execSQL("ALTER TABLE users ADD COLUMN email TEXT")
       }
       if (oldVersion < 3) {
           db.execSQL("CREATE INDEX idx_email ON users(email)")
       }
   }

9. Common Problem Solutions

   • Database Lock: Use WAL mode to improve concurrency
   • Performance Issues: Use EXPLAIN QUERY PLAN to analyze queries
   • Memory Leaks: Close database connections and cursors promptly
   • Data Loss: Regularly backup database

10. ORM Framework Selection

    • iOS: Core Data, Realm, GRDB
    • Android: Room, Realm, GreenDAO
    • React Native: react-native-sqlite-storage, WatermelonDB

SQLite is the preferred solution for local data storage in mobile applications, and mastering its best practices is crucial for mobile developers.