【Android入门到项目实战--4.5】—— SQLite数据库存储实现增删改查

import android.content.ContentValues
import android.content.Context
import android.database.Cursor
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
 
class DatabaseHelper(context: Context) : SQLiteOpenHelper(context, "NoteDatabase.db", null, 1) {
 
    override fun onCreate(db: SQLiteDatabase) {
        val createTableSQL = "CREATE TABLE NotesTable (" +
                "id INTEGER PRIMARY KEY AUTOINCREMENT, " +
                "title TEXT, " +
                "description TEXT)"
        db.execSQL(createTableSQL)
    }
 
    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        val dropTableSQL = "DROP TABLE IF EXISTS NotesTable"
        db.execSQL(dropTableSQL)
        onCreate(db)
    }
 
    fun insertData(title: String, description: String): Long {
        val db = this.writableDatabase
        val contentValues = ContentValues()
        contentValues.put("title", title)
        contentValues.put("description", description)
        val rowID = db.insert("NotesTable", null, contentValues)
        db.close()
        return rowID
    }
 
    fun deleteData(id: Long) {
        val db = this.writableDatabase
        db.delete("NotesTable", "id = ?", arrayOf(id.toString()))
        db.close()
    }
 
    fun updateData(id: Long, title: String, description: String) {
        val db = this.writableDatabase
        val contentValues = ContentValues()
        contentValues.put("title", title)
        contentValues.put("description", description)
        db.update("NotesTable", contentValues, "id = ?", arrayOf(id.toString()))
        db.close()
    }
 
    fun getAllData(): Cursor {
        val db = this.writableDatabase
        return db.query("NotesTable", null, null, null, null, null, null)
    }
}

这段代码实现了一个简单的SQLite数据库操作类，包括创建数据库、表、数据的插入、删除、更新以及查询操作。这个类可以作为Android开发中管理数据的一个基础示例。