Android

今天学习了Android的数据库相关知识，本次所用的数据库应该是该编译环境自带的数据库，没有链接mysql数据库
那么，窜建一个软件包来放置数据库建立的代码以及sql语句，这东西叫社么helper是个数据库保住工具
package com.example.try1.util;

import android.os.Bundle;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

import com.example.try1.R;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class MyDatabaseHelper extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "my_database.db";
private static final int DATABASE_VERSION = 1;// 表名和列名
public static final String TABLE_NAME = "my_table";
public static final String COLUMN_ID = "id";
public static final String COLUMN_NAME = "name";
public static final String COLUMN_AGE = "age";
public static final String COLUMN_HEIGHT = "height";
public static final String COLUMN_WEIGHT = "weight";// 创建表的 SQL 语句
private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" +COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +COLUMN_NAME + " TEXT NOT NULL, " +COLUMN_AGE + " TEXT NOT NULL, " +COLUMN_HEIGHT + " TEXT NOT NULL, " +COLUMN_WEIGHT + " TEXT NOT NULL);";public MyDatabaseHelper(Context context) {super(context, DATABASE_NAME, null, DATABASE_VERSION);
}@Override
public void onCreate(SQLiteDatabase db) {// 创建表db.execSQL(CREATE_TABLE);
}@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// 升级数据库时删除旧表并创建新表db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);onCreate(db);
}

}

在这篇代码里要写明数据库的名称，数据表格的名称和所建表格的行列名