How to get beginning of the first day of this week from timestamp in Android sqlite?

Before getting into an example, we should know what SQLite database in android is. SQLite is an open source SQL database that stores data to a text file on a device. Android comes in with built in SQLite database implementation. SQLite supports all the relational database features. In order to access this database, you don't need to establish any kind of connections for it like JDBC, ODBC etc.
This example demonstrates How to get the beginning of the first day of this week from the timestamp in Android SQLite.
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/activity_main.xml.
<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   xmlns:tools = "http://schemas.android.com/tools"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   tools:context = ".MainActivity"
   android:orientation = "vertical">
   <EditText
      android:id = "@+id/name"
      android:layout_width = "match_parent"
      android:hint = "Enter Name"
      android:layout_height = "wrap_content" />
   <EditText
      android:id = "@+id/salary"
      android:layout_width = "match_parent"
      android:inputType = "numberDecimal"
      android:hint = "Enter Salary"
      android:layout_height = "wrap_content" />
   <LinearLayout
      android:layout_width = "wrap_content"
      android:layout_height = "wrap_content">
      <Button
         android:id = "@+id/save"
         android:text = "Save"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content" />
      <Button
         android:id = "@+id/refresh"
         android:text = "Refresh"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content" />
      <Button
         android:id = "@+id/udate"
         android:text = "Update"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content" />
      <Button
         android:id = "@+id/Delete"
         android:text = "DeleteALL"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content" />
   </LinearLayout>
   <ListView
      android:id = "@+id/listView"
      android:layout_width = "match_parent"
      android:layout_height = "wrap_content">
   </ListView>
</LinearLayout>
In the above code, we have taken name and salary as Edit text, when user click on save button it will store the data into sqlite data base. Click on refresh button after insert values to update listview from cursor WITH THIS WEEK DATA. If User click on update button it will update the data.
Step 3 − Add the following code to src/MainActivity.java
package com.example.andy.myapplication;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
   Button save, refresh;
   EditText name, salary;
   private ListView listView;
   @Override
   protected void onCreate(Bundle readdInstanceState) {
      super.onCreate(readdInstanceState);
      setContentView(R.layout.activity_main);
      final DatabaseHelper helper = new DatabaseHelper(this);
      final ArrayList array_list = helper.getAllCotacts();
      name = findViewById(R.id.name);
      salary = findViewById(R.id.salary);
      listView = findViewById(R.id.listView);
      final ArrayAdapter arrayAdapter = new ArrayAdapter(MainActivity.this,
      android.R.layout.simple_list_item_1, array_list);
      listView.setAdapter(arrayAdapter);
      findViewById(R.id.Delete).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (helper.delete()) {
               Toast.makeText(MainActivity.this, "Deleted", Toast.LENGTH_LONG).show();
            } else {
               Toast.makeText(MainActivity.this, "NOT Deleted", Toast.LENGTH_LONG).show();
            }
         }
      });
      findViewById(R.id.udate).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (!name.getText().toString().isEmpty() && !salary.getText().toString().isEmpty()) {
               if (helper.update(name.getText().toString(), salary.getText().toString())) {
                  Toast.makeText(MainActivity.this, "Updated", Toast.LENGTH_LONG).show();
               } else {
                  Toast.makeText(MainActivity.this, "NOT Updated", Toast.LENGTH_LONG).show();
               }
            } else {
               name.setError("Enter NAME");
               salary.setError("Enter Salary");
            }
         }
      });
      findViewById(R.id.refresh).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            array_list.clear();
            array_list.addAll(helper.getAllCotacts());
            arrayAdapter.notifyDataSetChanged();
            listView.invalidateViews();
            listView.refreshDrawableState();
         }
      });
      findViewById(R.id.save).setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (!name.getText().toString().isEmpty() && !salary.getText().toString().isEmpty()) {
               if (helper.insert(name.getText().toString(), salary.getText().toString())) {
                  Toast.makeText(MainActivity.this, "Inserted", Toast.LENGTH_LONG).show();
               } else {
                  Toast.makeText(MainActivity.this, "NOT Inserted", Toast.LENGTH_LONG).show();
               }
            } else {
               name.setError("Enter NAME");
               salary.setError("Enter Salary");
            }
         }
      });
   }
}
Step 4 − Add the following code to src/ DatabaseHelper.java
package com.example.andy.myapplication;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import java.io.IOException;
import java.util.ArrayList;
class DatabaseHelper extends SQLiteOpenHelper {
   public static final String DATABASE_NAME = "salaryDatabase5";
   public static final String CONTACTS_TABLE_NAME = "SalaryDetails";
   public DatabaseHelper(Context context) {
      super(context,DATABASE_NAME,null,1);
   }
   @Override
   public void onCreate(SQLiteDatabase db) {
      try {
         db.execSQL(
            "create table "+ CONTACTS_TABLE_NAME +"(id INTEGER PRIMARY KEY, name text,salary                     text,datetime default current_timestamp )"
         );
      } catch (SQLiteException e) {
         try {
            throw new IOException(e);
         } catch (IOException e1) {
            e1.printStackTrace();
         }
      }
   }
   @Override
   public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
      db.execSQL("DROP TABLE IF EXISTS "+CONTACTS_TABLE_NAME);
      onCreate(db);
   }
   public boolean insert(String s, String s1) {
      SQLiteDatabase db = this.getWritableDatabase();
      ContentValues contentValues = new ContentValues();
      contentValues.put("name", s);
      contentValues.put("salary", s1);
      db.replace(CONTACTS_TABLE_NAME, null, contentValues);
      return true;
   }
   public ArrayList getAllCotacts() {
      SQLiteDatabase db = this.getReadableDatabase();
      ArrayList<String> array_list = new ArrayList<String>();
      Cursor res = db.rawQuery( "select (id ||' : '||name || ' : ' || salary || ' : '|| datetime)          AS fullname from "+CONTACTS_TABLE_NAME+" WHERE datetime > = DATE('now', 'weekday 0', '-7 days') ", null );
      res.moveToFirst();
      while(res.isAfterLast() = = false) {
         array_list.add(res.getString(res.getColumnIndex("fullname")));
         res.moveToNext();
      }
      return array_list;
   }
   public boolean update(String s, String s1) {
      SQLiteDatabase db = this.getWritableDatabase();
      db.execSQL("UPDATE "+CONTACTS_TABLE_NAME+" SET name = "+"'"+s+"', "+ "salary = "+"'"+s1+"'");
      return true;
   }
   public boolean delete() {
      SQLiteDatabase db = this.getWritableDatabase();
      db.execSQL("DELETE from "+CONTACTS_TABLE_NAME);
      return true;
   }
}
Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from the android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –
In the above result, we are showing one-week data of this week and as per our database records we have only two days records so it is showing only two dates data.
Click here to download the project code