안드로이드 데이터베이스 예시

package com.jwlee.quiz_budongsan;

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

import androidx.annotation.Nullable;

public class DatabaseHelper extends SQLiteOpenHelper {

public static final String DATABASE_NAME = "STUDENT.db"; // 데이터베이스 명
public static final String TABLE_NAME = "student_table"; // 테이블 명


// 테이블 항목
public static final String COL_1 = "ID";
public static final String COL_2 = "Name";
public static final String COL_3 = "Correct_Rate";



public DatabaseHelper(@Nullable Context context) {
super(context, DATABASE_NAME, null, 3);
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_NAME + "(ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, CORRECT_RATE TEXT)");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+ TABLE_NAME);
onCreate(db);

}

// 데이터베이스 추가하기 insert

public boolean insertData(String name, String correct_Rate){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_2,name);
contentValues.put(COL_3,correct_Rate);

long result = db.insert(TABLE_NAME, null,contentValues);
if(result == -1)
return false;
else
return true;

}

//데이터베이스 항목 모두 읽어오기 Read
public Cursor getAllData(){
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
return res;
}

//데이터베이스 선택한항목만 읽어오기 Read
public Cursor getSelectData(String select_name){
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from "+TABLE_NAME + " where name = " + "\""+ select_name+ "\"",null);//select * from student_table where name = "민법"
return res;
}

// 데이터베이스 삭제하기
public Integer deleteData(String id){
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME, "ID = ? ",new String[]{id});
}

//데이터베이스 수정하기
public boolean updateData(String id, String name, String correct_Rate){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_1,id);
contentValues.put(COL_2,name);
contentValues.put(COL_3,correct_Rate);

db.update(TABLE_NAME,contentValues,"ID = ?", new String[] { id });
return true;
}
}