Let's get started! Create a project named Database, name the package com.oreillyschool.android1.database, and assign it to the Android1_Lessons working set.

I found a dbhelper class which copies my previously. Inserting and Deleting values in with my. I can read data by running a query on cursor c. In this article we will study how to access a simple database driven Web Service from a Desktop application. Here I have a DbHelper class which has openconnection. Method Description Defined By; addTablePrefix() Prepares a table name for Yii to add its table prefix: DbHelper: escapeParam() Escapes commas and asterisks in a.

The primary class for interacting with a SQLite database in Android is the SQLiteOpenHelper class. The SQLiteOpenHelper class is an abstract class to be used for creation and version management of the SQLite database. Let's set up a basic SQLiteOpenHelper implementation first. In the Database project, create a new class file named DBHelper that extends the SQLiteOpenHelper class. SQLiteOpenHelper has two abstract methods that we must implement: onCreate() and onUpgrade(). Each method is intended to be used to modify the structure of a database after the respective event.

During onCreate, we'll set up the basic tables for all the data, and in onUpgrade, we'll enter any migration logic needed to convert a database from an older version to match the new database. Make sure that both methods result in the database having the same schema, regardless of whether they just installed the application or are updating from a previous application version. You might have noticed that the class generated from the 'New Class Wizard' throws a compiler error initially. This is because we haven't implemented a constructor for the class to complete our implementation. Let's tackle that now. Make these changes to your code. Here we have two buttons at the top: one to add rows to the database and one to remove rows.

We'll also use a ListView to display the data in the database. Next, let's create a view for a dialog that can be present when we click the New Person button. Create a new Android Layout XML file named add_person_dialog and make these changes. This basic view with an EditText and two Buttons should work. Next, modify MainActivity.java to hook the dialog up to the 'Add Person' button and implement an insert on our database. We made a few changes to the list here to allow us to select an individual row. The default layout simple_list_item_single_choice looks just like the previous layout, but with a RadioButton added to the side of the row as well.

By calling setChoiceMode() on the list earlier and giving it the parameter ListView.CHOICE_MODE_SINGLE, we instruct the list to manage the checked row, and to allow only one row to be checked at a time. In the onDeleteClicked() method, we implemented the delete action. We use the ListView method getCheckedItemPosition() to find out which item is checked. This could potentially be -1 if no item is checked, so we code defensively around that. Then we have to use the ListAdapter to retireve the actual row id of the item. This corresponds to the '_id' column of the data in the database.

Finally, we get a writable version of the database from our helper again, only this time we call delete, giving it the table name, and an SQL 'WHERE' clause to delete just the row that matches the '_id' of the list item that is checked. Passing null to the second argument would delete all rows in the table.

The final argument is used to help sanitize the query again by replacing any question marks in the 'WHERE' clause with a sanitized value from the third argument. We aren't concerned with that here, so we just pass in null. If any rows were affected by our delete query, then we update the adapter (after closing the database, of course). Properly managing a database in Android can seem like quite a daunting task. Thankfully Android has provided many convenient helper classes to make that easier. Hopefully by now you're feeling comfortable with performing the CRUD actions (create, read, update, delete) on a database in Android. Install Asterisknow From Usb Stick. There's a lot of advanced SQLite content that we didn't cover in this lesson, but this is an excellent foundation and usually enough for most applications.