I have an app and I didn't use database up the present.Now I will update my app and this app contains a database.I am curious about this.Which method will call on updated phones in database onCreate or onUpgrade ?
first time if db don't exist, onCreate() method will run.
if db exist and your current db version is higher than installed version, onUpgrade() will run and you should check version in onUpgrade method and do what you want.
here is an example of dbHandler.java class.
package com.app.util;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Milad
*/
public class DBHandler extends SQLiteOpenHelper {
private static final String DB_NAME = "YourDbName";
private static final int DB_VERSION = 1;
public DBHandler(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
//Create firstTable
db.execSQL("CREATE TABLE TEST ( _id INTEGER PRIMARY KEY AUTOINCREMENT, Name TEXT);");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
if (oldVersion >2) {
db.execSQL("DROP TABLE IF EXISTS TEST");
onCreate(db);
}
}
}
When you first create the database onCreate() method will be called. If you upgrade the database version then that time onUpgrade() method will be called.
Related
A lot of questions already have been asked about this but none of them seems to be working for me.
I open the file explorer>data>data>package name>database>mydatabase.db in order to get my database and i save it on my pc n try to see it using db browser for sqlite. But there's no table.
here's the helper class that extends sqliteOpenHelper:
package famiddle.smart.apps.businessmanager;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class BusinessDbHelper extends SQLiteOpenHelper {
// If you change the database schema, you must increment the database version.
public static final String DATABASE_NAME = "BusinessManager.db";
public static final int DATABASE_VERSION = 1;
// SQL query for creating the table for items name
private static final String SQL_CREATE_ITEMS_NAME_TABLE =
"CREATE TABLE itmes_name(id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, items_name TEXT NOT NULL);" ;
public BusinessDbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL(SQL_CREATE_ITEMS_NAME_TABLE);
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
}
In my one of app's activity, I instantiate above class and run a method getReadableDatabase() so that the database can be created with the table.
package famiddle.smart.apps.businessmanager;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import androidx.appcompat.app.AppCompatActivity;
public class PurchaseActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_purchase);
// Instantiate the subclass of SQLiteOpenHelper.
BusinessDbHelper dbHelper = new BusinessDbHelper(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();
}
what do i do?
Everything is fine with this code. I wasn't extracting two other files with the database file and wasn't putting it into one folder. When I did put all three files into one folder and opened the file with .db extension using the db browser for SQLite, I could see the tables.
i have a very simple code i am trying to create SQL lite database but it's not creating while i check my DEVICE FILE EXPLORER folder there is not any database folder there under my apps folder.
here is the code:
DatabaseHelper.java
package com.example.ali.schoolapp;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "Student.db";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
#Override
public void onCreate(SQLiteDatabase db) {
db = this.getWritableDatabase();
db.execSQL("CREATE TABLE Items " + " (id INTEGER PRIMARY KEY AUTOINCREMENT,name TEXT, description TEXT)");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
onCreate(db);
}
}
MainActivity.java
package com.example.ali.schoolapp;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
DatabaseHelper myDb;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myDb = new DatabaseHelper(this);
}
}
The database will not get created until you attempt to do something with it. Only then (when getWritableDatabase or getReadableDatabase is called) will the database be created.
So you could try :-
myDb = new DatabaseHelper(this); //<<<<<<<<<<< EXISTING LINE
Cursor csr = myDB.getWritableDatabase().query("Items",null,null,null,null,null,null);
csr.close();
And then the Database would have been created.
Note the above isn't how you would typically access the database, it's a quick fix. Normally you'd have you access methods in a Class (perhaps in the DatabaseHelper Class).
P.S. your onUpgrade method would very likely fail if you changed the version number (4th parameter (which is 1) when you call super). That is onUpgrade calls onCreate as the table exists you will get an error. You would typically DROP the table before calling onCreate).
I have the following Java Class
package com.sjhdevelopment.shaunharrison.myejuiceapp;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MyDBHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "EJuiceData.db";
public static final int DATABASE_VERSION = 1;
public MyDBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void onCreate(SQLiteDatabase database) {
database.execSQL("create table if not exists Inventory");
}
#Override
public void onUpgrade(SQLiteDatabase database, int oldVersion, int newVersion) {
if (newVersion > oldVersion)
database.execSQL("ALTER TABLE Recipe ADD COLUMN NOTES TEXT");
onCreate(database);
}
}
Then in my main activity I have the following;
public class Calculation extends AppCompatActivity {
private MyDBHelper dbHelper;
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calculation);
try {
dbHelper = new MyDBHelper(this);
dbHelper.getWritableDatabase();
}
catch(Exception e)
{
showError("Error", e.getMessage());
}
}
However, when I debug the code to see if the database + tables are being created with a break point on the try and on the database.execSQL("create....
There debugger doesn't actually go into the MyDBHelper class to do anything, therefore I'm assuming that the database + tables aren't being created
I've looked online and it says that when a getWritableDatabase/readable is called the onCreate method should get called
Any idea's as to what I'm doing wrong?
onCreate(...) is only called when the database is created for the first time. If you want to change your database you have to increase DATABASE_VERSION then it will jump into onUpgrade(...)
It looks like your SQL is not correct onCreate. Instead of database.execSQL("create table if not exists Inventory"); it should be
database.execSQL("CREATE TABLE table_name
(id_column INTEGER PRIMARY KEY
, column_name TEXT);";
You need to manually created every table with all the corrected columns. They will be created once you call the database for the first time.
I am new to Android Programming.. I am trying to create sqLite Database in android Here is my code
sqLitee.java
package com.example.sqlite;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class sqLitee extends SQLiteOpenHelper
{
public static final String DB_NAME="student.db";
public static final String TABLE_NAME="student";
public static final String COL_1="ID";
public static final String COL_2="FIRST_NAME";
public static final String COL_3="LAST_NAME";
public static final String COL_4="MARKS";
public sqLitee(Context context)
{
super(context, DB_NAME,null, 1);
// TODO Auto-generated constructor stub
SQLiteDatabase db=this.getWritableDatabase();
}
#Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE " + TABLE_NAME + "(ID INTEGER PRIMARY KEY AUTO INCREMENT, FIRST_NAME TEXT, LAST_NAME TEXT, MARKS INTEGER)");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXIST " + TABLE_NAME);
onCreate(db);
}
}
MainActivity.java
package com.example.sqlite;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends Activity {
sqLitee myDB;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
myDB = new sqLitee(this);
setContentView(R.layout.activity_main);
}
}
When I am trying to run it on Android virtual Device , It says unfortunately , sqLite has stopped..
Thanks
remove this line in your sqllite constructor:
SQLiteDatabase db=this.getWritableDatabase();
you try to get the db, which is currently initializing.
There's a syntax error in your CREATE TABLE SQL. AUTO INCREMENT should be AUTOINCREMENT.
As always, first see the logcat for exception stacktrace and to learn what is failing and where.
I'm newbie to android. I have gone through the android docs and I googled it, but I'm confused why my code is returning a no such table error.
I want to create a DB named as demo and I want to create a table student with three columns.
Here's my code:
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
static final String dbName="demo";
public DatabaseHelper(Context context) {
super(context, dbName, null, 1);
// TODO Auto-generated constructor stub
}
#Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("Create table IF NOT EXISTS student(title text,address text,gender text)");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
public void insert_datas(String title,String artist,String patharray,String table_name){
SQLiteDatabase db=this.getWritableDatabase();
ContentValues initialValues = new ContentValues();
initialValues.put("title",title);
initialValues.put("address",address);
initialValues.put("gender",gender);
long n = db.insert(table_name,title,initialValues);
System.out.println("n"+n);
db.close();
}
public Cursor get_datas(){
SQLiteDatabase db=this.getReadableDatabase();
Cursor cur=db.rawQuery("SELECT * FROM student",null);
return cur;
}
}
and this how i m call the DatabaseHelper class:
public class MYActivity extends Activity{
DatabaseHelper dbAdapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.customlist);
dbAdapter = new DatabaseHelper(this);
dbAdapter.insert_datas("test","test","test","student");
}
}
My error
**11-26 02:10:00.210: INFO/SqliteDatabaseCpp(27151): sqlite returned: error code = 1, msg = no such table: student, db=/data/data/com.player.activites/databases/demo
11-26 02:10:00.210: ERROR/SQLiteDatabase(27151): android.database.sqlite.SQLiteException: no such table: student: , while compiling: INSERT INTO studenty(title,address,gender) VALUES (?,?,?)**
Thanks
Try upgrading the database version number (right now you have it as 1). Is it possible you ran your app and tried to access the DB before your helper's onCreate actually did anything? If you did that, you would have an empty DB at version 1. If you don't want to increment your version numbers, you could alternatively uninstall your app or clear its data to delete the DB file entirely.