[Android] 가수 그룹 관리 DB 만들기

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp"
    tools:context=".MainActivity">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="20dp"
            android:text="이름 :"/>
        <EditText
            android:id="@+id/edtName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"/>
    </LinearLayout>
    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="20dp"
            android:text="인원 :"/>
        <EditText
            android:id="@+id/edtNumber"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"/>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
>
        <Button
            android:id="@+id/btnInit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="5dp"
            android:backgroundTint="#50000000"
            android:textColor="@color/black"
            android:text="초기화"/>
        <Button
            android:id="@+id/btnInsert"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="5dp"
            android:backgroundTint="#50000000"
            android:textColor="@color/black"
            android:text="입력"/>
        <Button
            android:id="@+id/btnSeclect"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:backgroundTint="#50000000"
            android:textColor="@color/black"
            android:text="조회"/>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:gravity="center">
        <EditText
            android:id="@+id/edtNameResult"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="25dp"/>
        <EditText
            android:id="@+id/edtNumberResult"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
    </LinearLayout>

</LinearLayout>

MainActivity.java

package com.example.project12_2;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {
    myDBHelper myHelper;
    EditText edtName, edtNumber, edtNameResult, edtNumberResult;
    Button btnInit, btnInsert, btnSelect;
    SQLiteDatabase sqlDB;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setTitle("가수 그룹 관리 DB");

        edtName = (EditText) findViewById(R.id.edtName);
        edtNumber = (EditText) findViewById(R.id.edtNumber);
        edtNameResult = (EditText) findViewById(R.id.edtNameResult);
        edtNumberResult = (EditText) findViewById(R.id.edtNumberResult);
        btnInit = (Button) findViewById(R.id.btnInit);
        btnInsert = (Button) findViewById(R.id.btnInsert);
        btnSelect = (Button) findViewById(R.id.btnSeclect);

        myHelper = new myDBHelper(this);
        btnInit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                sqlDB = myHelper.getWritableDatabase();
                //onUpgrade 호출, groupTBL이 있다면 삭제한 후 새로 생성한다
                myHelper.onUpgrade(sqlDB,1,2);
                //Database를 닫는다
                sqlDB.close();
            }
        });

        btnInsert.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){
                //groupDB를 쓰기용으로 연다
                sqlDB=myHelper.getWritableDatabase();
                sqlDB.execSQL("INSERT INTO groupTBL VALUES ('"+edtName.getText().toString()+"',"+edtNumber.getText().toString()+");");
                sqlDB.close();
                Toast.makeText(getApplicationContext(),"입력됨",Toast.LENGTH_SHORT).show();
                edtName.setText("");
                edtNumber.setText("");
            }
        });

        btnSelect.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                sqlDB = myHelper.getReadableDatabase();
                Cursor cursor;
                cursor = sqlDB.rawQuery("SELECT * FROM groupTBL;",null);
                String strNames = "그룹 이름"+"\r\n"+"--------"+"\r\n";
                String strNumbers = "인원"+"\r\n"+"--------"+"\r\n";

                while(cursor.moveToNext()){
                    strNames+=cursor.getString(0)+"\r\n";
                    strNumbers+=cursor.getString(1)+"\r\n";
                }

                edtNameResult.setText(strNames);
                edtNumberResult.setText(strNumbers);

                cursor.close();
                sqlDB.close();

            }
        });
    }


    public class myDBHelper extends SQLiteOpenHelper{
        public myDBHelper(Context context){
            // 두번째 파라미터에는 새로 생성될 데이터베이스의 파일명을 지정하면 된다.
            super(context, "groupDB",null,1);
        }
        @Override
        // onUpgrade()에서 호출되거나 데이터를 입력할 때 혹은 테이블이 없을 때 처음 1회 호출한다.
        public void onCreate(SQLiteDatabase db){
            db.execSQL("CREATE TABLE groupTBL ( gName CHAR(20) PRIMARY KEY, gNumber INTEGER);");
        }
        @Override
        //테이블을 삭제하고 새로 생성한다. 초기화할 때 호출한다.
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
            db.execSQL("DROP TABLE IF EXISTS groupTBL");
            onCreate(db);
        }
    }
}

배운 점

자바 파일에서 SQLiteOpenHelper를 이용하여 직접 DB를 만들 수 있다.

 

실행 영상

 

DB에 데이터가 저장 된 모습