[Android] SQLite 정의 및 회원가입 예제

SQLite 란?

1. 개발시 간략한 DB 필요할 경우가 있음. SQLite을 사용하여 간략한 DB 생성하여 사용 가능

2. 서버를 타지 않고 단말기 내에서만 처리되어야 하는 데이터의 경우 SQLite사용

SQLite 사용

1. DBHelper 클래스 생성 -> SQLiteOpenHelper 상속

2.DBHelper 클래스는 새로운 테이블 생성하고 데이터 삽입,삭제 하는 등 전반적으로 SQLite를 관리

3. onCreate, onUpgrade함수 필수적 추가

예) 데이터 추가하여 보여주기, 채팅같은것들

SQLite Example ) 

Step 1: Create a New Project and Name it SQLiteOperations.
Step 2: Open res -> layout -> activity_main.xml (or) main.xml and add following code:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.sqliteoperations.MainActivity"
    android:background="@android:color/holo_blue_dark">
 
    <TextView
        android:text="@string/username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginTop="12dp"
        android:id="@+id/textView"
        android:textSize="18sp"
        android:textStyle="bold|italic"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:gravity="center" />
 
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:id="@+id/editName"
        android:textStyle="bold|italic"
        android:layout_below="@+id/textView"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:hint="Enter Name"
        android:gravity="center_vertical|center" />
 
    <TextView
        android:text="@string/password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="13dp"
        android:id="@+id/textView2"
        android:textStyle="bold|italic"
        android:textSize="18sp"
        android:layout_below="@+id/editName"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:gravity="center"
        android:hint="Enter Password" />
 
    <Button
        android:text="@string/view_data"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button2"
        android:textSize="18sp"
        android:onClick="viewdata"
        android:textStyle="bold|italic"
        android:layout_alignBaseline="@+id/button"
        android:layout_alignBottom="@+id/button"
        android:layout_alignRight="@+id/button4"
        android:layout_alignEnd="@+id/button4" />
 
    <Button
        android:text="@string/add_user"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:textStyle="bold|italic"
        android:textSize="18sp"
        android:onClick="addUser"
        android:layout_marginLeft="28dp"
        android:layout_marginStart="28dp"
        android:layout_below="@+id/editPass"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="23dp" />
 
    <Button
        android:text="@string/update"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button3"
        android:onClick="update"
        android:textStyle="normal|bold"
        android:layout_below="@+id/editText3"
        android:layout_alignLeft="@+id/button4"
        android:layout_alignStart="@+id/button4"
        android:layout_marginTop="13dp" />
 
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:id="@+id/editText6"
        android:layout_alignTop="@+id/button4"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:freezesText="false"
        android:hint="Enter Name to Delete Data"
        android:layout_toLeftOf="@+id/button2"
        android:layout_toStartOf="@+id/button2" />
 
    <Button
        android:text="@string/delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginRight="21dp"
        android:layout_marginEnd="21dp"
        android:id="@+id/button4"
        android:onClick="delete"
        android:textStyle="normal|bold"
        tools:ignore="RelativeOverlap"
        android:layout_marginBottom="41dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />
 
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:layout_marginTop="47dp"
        android:id="@+id/editText3"
        android:textStyle="bold|italic"
        android:textSize="14sp"
        android:layout_below="@+id/button"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="7dp"
        android:layout_marginStart="7dp"
        android:hint="Current Name" />
 
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="textPassword"
        android:ems="10"
        android:layout_marginTop="11dp"
        android:id="@+id/editPass"
        android:hint="Enter Password"
        android:gravity="center_vertical|center"
        android:textSize="18sp"
        android:layout_below="@+id/textView2"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:textAllCaps="false"
        android:textStyle="normal|bold" />
 
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:id="@+id/editText5"
        android:textStyle="bold|italic"
        android:textSize="14sp"
        android:hint="New Name"
        android:layout_alignTop="@+id/button3"
        android:layout_alignLeft="@+id/editText3"
        android:layout_alignStart="@+id/editText3"
        android:layout_marginTop="32dp" />
</RelativeLayout>
 

Step 3 : Now open app -> java -> package -> MainActivity.java and add the below code.

package com.example.sqliteoperations;
 
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
 
public class MainActivity extends AppCompatActivity {
    EditText Name, Pass , updateold, updatenew, delete;
    myDbAdapter helper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Name= (EditText) findViewById(R.id.editName);
        Pass= (EditText) findViewById(R.id.editPass);
        updateold= (EditText) findViewById(R.id.editText3);
        updatenew= (EditText) findViewById(R.id.editText5);
        delete = (EditText) findViewById(R.id.editText6);
 
        helper = new myDbAdapter(this);
    }
    public void addUser(View view)
    {
        String t1 = Name.getText().toString();
        String t2 = Pass.getText().toString();
        if(t1.isEmpty() || t2.isEmpty())
        {
            Message.message(getApplicationContext(),"Enter Both Name and Password");
        }
        else
        {
            long id = helper.insertData(t1,t2);
            if(id<=0)
            {
                Message.message(getApplicationContext(),"Insertion Unsuccessful");
                Name.setText("");
                Pass.setText("");
            } else
            {
                Message.message(getApplicationContext(),"Insertion Successful");
                Name.setText("");
                Pass.setText("");
            }
        }
    }
 
    public void viewdata(View view)
    {
        String data = helper.getData();
        Message.message(this,data);
    }
 
    public void update( View view)
    {
        String u1 = updateold.getText().toString();
        String u2 = updatenew.getText().toString();
        if(u1.isEmpty() || u2.isEmpty())
        {
            Message.message(getApplicationContext(),"Enter Data");
        }
        else
        {
            int a= helper.updateName( u1, u2);
            if(a<=0)
            {
                Message.message(getApplicationContext(),"Unsuccessful");
                updateold.setText("");
                updatenew.setText("");
            } else {
                Message.message(getApplicationContext(),"Updated");
                updateold.setText("");
                updatenew.setText("");
            }
        }
 
    }
    public void delete( View view)
    {
        String uname = delete.getText().toString();
        if(uname.isEmpty())
        {
            Message.message(getApplicationContext(),"Enter Data");
        }
        else{
            int a= helper.delete(uname);
            if(a<=0)
            {
                Message.message(getApplicationContext(),"Unsuccessful");
                delete.setText("");
            }
            else
            {
                Message.message(this, "DELETED");
                delete.setText("");
            }
        }
    }
}

Step 4: In this step create a java class myDbAdapter. java.

package com.example.sqliteoperations;
 
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
 
 
public class myDbAdapter {
    myDbHelper myhelper;
    public myDbAdapter(Context context)
    {
        myhelper = new myDbHelper(context);
    }
 
    public long insertData(String name, String pass)
    {
        SQLiteDatabase dbb = myhelper.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(myDbHelper.NAME, name);
        contentValues.put(myDbHelper.MyPASSWORD, pass);
        long id = dbb.insert(myDbHelper.TABLE_NAME, null , contentValues);
        return id;
    }
 
    public String getData()
    {
        SQLiteDatabase db = myhelper.getWritableDatabase();
        String[] columns = {myDbHelper.UID,myDbHelper.NAME,myDbHelper.MyPASSWORD};
        Cursor cursor =db.query(myDbHelper.TABLE_NAME,columns,null,null,null,null,null);
        StringBuffer buffer= new StringBuffer();
        while (cursor.moveToNext())
        {
            int cid =cursor.getInt(cursor.getColumnIndex(myDbHelper.UID));
            String name =cursor.getString(cursor.getColumnIndex(myDbHelper.NAME));
            String  password =cursor.getString(cursor.getColumnIndex(myDbHelper.MyPASSWORD));
            buffer.append(cid+ "   " + name + "   " + password +" \n");
        }
        return buffer.toString();
    }
 
    public  int delete(String uname)
    {
        SQLiteDatabase db = myhelper.getWritableDatabase();
        String[] whereArgs ={uname};
 
        int count =db.delete(myDbHelper.TABLE_NAME ,myDbHelper.NAME+" = ?",whereArgs);
        return  count;
    }
 
    public int updateName(String oldName , String newName)
    {
        SQLiteDatabase db = myhelper.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(myDbHelper.NAME,newName);
        String[] whereArgs= {oldName};
        int count =db.update(myDbHelper.TABLE_NAME,contentValues, myDbHelper.NAME+" = ?",whereArgs );
        return count;
    }
 
    static class myDbHelper extends SQLiteOpenHelper
    {
        private static final String DATABASE_NAME = "myDatabase";    // Database Name
        private static final String TABLE_NAME = "myTable";   // Table Name
        private static final int DATABASE_Version = 1;.    // Database Version
        private static final String UID="_id";     // Column I (Primary Key)
        private static final String NAME = "Name";    //Column II
        private static final String MyPASSWORD= "Password";    // Column III
        private static final String CREATE_TABLE = "CREATE TABLE "+TABLE_NAME+
                " ("+UID+" INTEGER PRIMARY KEY AUTOINCREMENT, "+NAME+" VARCHAR(255) ,"+ MyPASSWORD+" VARCHAR(225));";
        private static final String DROP_TABLE ="DROP TABLE IF EXISTS "+TABLE_NAME;
        private Context context;
 
        public myDbHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_Version);
            this.context=context;
        }
 
        public void onCreate(SQLiteDatabase db) {
 
            try {
                db.execSQL(CREATE_TABLE);
            } catch (Exception e) {
                Message.message(context,""+e);
            }
        }
 
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            try {
                Message.message(context,"OnUpgrade");
                db.execSQL(DROP_TABLE);
                onCreate(db);
            }catch (Exception e) {
                Message.message(context,""+e);
            }
        }
    }
}

Step 5: In this step create another java class Message.class

package com.example.sqliteoperations;
 
import android.content.Context;
import android.widget.Toast;
 
public class Message {
    public static void message(Context context, String message) {
        Toast.makeText(context, message, Toast.LENGTH_LONG).show();
    }
}

최종 결과 

reference : https://abhiandroid.com/database/sqlite