Android使用SQLite数据库实现基本的增删改查

import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
 
class DatabaseHelper(context: Context) : SQLiteOpenHelper(context, "mydatabase.db", null, 1) {
 
    override fun onCreate(db: SQLiteDatabase) {
        val createTableStatement = "CREATE TABLE IF NOT EXISTS user_table " +
                "(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER)"
        db.execSQL(createTableStatement)
    }
 
    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        // 这里处理数据库升级的逻辑
    }
 
    fun insertData(name: String, age: Int) {
        val db = this.writableDatabase
        val contentValues = ContentValues()
        contentValues.put("name", name)
        contentValues.put("age", age)
        val success = db.insert("user_table", null, contentValues)
        db.close()
    }
 
    fun deleteData(id: Int) {
        val db = this.writableDatabase
        db.delete("user_table", "id = ?", arrayOf(id.toString()))
        db.close()
    }
 
    fun updateData(id: Int, name: String, age: Int) {
        val db = this.writableDatabase
        val contentValues = ContentValues()
        contentValues.put("name", name)
        contentValues.put("age", age)
        db.update("user_table", contentValues, "id = ?", arrayOf(id.toString()))
        db.close()
    }
 
    fun retrieveData(): Cursor {
        val db = this.readableDatabase
        return db.query("user_table", null, null, null, null, null, null)
    }
}

这段代码展示了如何在Android中使用SQLiteOpenHelper创建和管理一个简单的数据库，并实现了基本的增删改查操作。使用时，你需要创建DatabaseHelper的实例，并调用相应的方法来执行数据库操作。