If there is no index named index-name but there is a WITHOUT ROWID table with that name, then (as of SQLite version 3.30.0 on 2019-10-04) this pragma returns the PRIMARY KEY columns of the WITHOUT ROWID table as they are used in the records of the underlying b-tree, which is to say with duplicate columns removed. SQLite autoincrement FAQ: How do I get the autoincrement value from my last SQLite INSERT command? You can get the integer value of the primary key field from the last insert into an autoincrement field using a SQLite function named lastinsertrowid, as shown in the example below. Summary: in this tutorial, you will learn how to use SQLite PRIMARY KEY constraint to define a primary key for a table. Introduction to SQLite primary key. A primary key is a column or group of columns used to identify the uniqueness of rows in a table. The AUTOINCREMENT keyword imposes extra CPU, memory, disk space, and disk I/O overhead and should be avoided if not strictly needed. It is usually not needed. In SQLite, a column with type INTEGER PRIMARY KEY is an alias for the ROWID (except in WITHOUT ROWID tables) which is always a 64-bit signed integer.
Nov 13, 2014 Generator for SQLite Use in Android. This is a reference link to file that will help to generate special scripts while coding in Android.
SQLite is a opensource 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 e.t.c
Database - Package
The main package is android.database.sqlite that contains the classes to manage your own databases
Database - Creation
In order to create a database you just need to call this method openOrCreateDatabase with your database name and mode as a parameter. It returns an instance of SQLite database which you have to receive in your own object.Its syntax is given below
Apart from this , there are other functions available in the database package , that does this job. They are listed below
Database - Insertion
we can create table or insert data into table using execSQL method defined in SQLiteDatabase class. Its syntax is given below
This will insert some values into our table in our database. Another method that also does the same job but take some additional parameter is given below
Database - Fetching
We can retrieve anything from database using an object of the Cursor class. We will call a method of this class called rawQuery and it will return a resultset with the cursor pointing to the table. We can move the cursor forward and retrieve the data.
There are other functions available in the Cursor class that allows us to effectively retrieve the data. That includes
Database - Helper class
For managing all the operations related to the database , an helper class has been given and is called SQLiteOpenHelper. It automatically manages the creation and update of the database. Its syntax is given below
ExampleAndroid Sqlite Library
Here is an example demonstrating the use of SQLite Database. It creates a basic contacts applications that allows insertion, deletion and modification of contacts.
To experiment with this example, you need to run this on an actual device on which camera is supported.
Following is the content of the modified MainActivity.java.
Following is the modified content of display contact activity DisplayContact.java
Following is the content of Database class DBHelper.java
Following is the content of the res/layout/activity_main.xml
Following is the content of the res/layout/activity_display_contact.xml
Following is the content of the res/value/string.xml
Following is the content of the res/menu/main_menu.xml
Following is the content of the res/menu/display_contact.xml
This is the defualt AndroidManifest.xml of this project
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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 Android studio , open one of your project's activity files and click Run icon from the tool bar. Before starting your application,Android studio will display following window to select an option where you want to run your Android application.
Select your mobile device as an option and then check your mobile device which will display following screen −
Now open your optional menu, it will show as below image: Optional menu appears different places on different versions
Click on the add button of the menu screen to add a new contact. It will display the following screen −
It will display the following fields. Please enter the required information and click on save contact. It will bring you back to main screen.
Now our contact sai has been added.In order to see that where is your database is created. Open your android studio, connect your mobile. Go tools/android/android device monitor. Now browse the file explorer tab. Now browse this folder /data/data/<your.package.name>/databases<database-name>.
The SQLite.NET library that Xamarin recommends is a very basic ORM thatlets you easily store and retrieve objects in the local SQLite databaseon an Android device. ORM stands for Object Relational Mapping – anAPI that lets you save and retrieve 'objects' from a databasewithout writing SQL statements.
To include the SQLite.NET library in a Xamarin app, add the following NuGet package to your project:
Tip
There are a number of different SQLite packages available – be sure to choose the correct one (it might not be the top result in search).
Once you have the SQLite.NET library available, follow these three steps to use it to access a database:
Basic Data Access Sample
The DataAccess_Basic sample code for this document looks like thiswhen running on Android. The code illustrates how to perform simpleSQLite.NET operations and shows the results in as text in theapplication's main window.
Android
The following code sample shows an entire database interaction usingthe SQLite.NET library to encapsulate the underlying database access.It shows:
Auto Generate Key Sqlite Android Download
You'll need to include these namespaces:
The last one requires that you have added SQLite to your project. Notethat the SQLite database table is defined by adding attributes to aclass (the
Stock class) rather than a CREATE TABLE command.
Using the
[Table] attribute without specifying a table name parameterwill cause the underlying database table to have the same name as theclass (in this case, 'Stock'). The actual table name is importantif you write SQL queries directly against the database rather than usethe ORM data access methods. Similarly the [Column('_id')] attributeis optional, and if absent a column will be added to the table with thesame name as the property in the class.
SQLite Attributes
Common attributes that you can apply to your classes to control howthey are stored in the underlying database include:
Most of these attributes are optional. You should always specify an integerprimary key so that selection and deletion queries can be performedefficiently on your data.
More Complex QueriesAuto Generate Key Sqlite Android Software
The following methods on
SQLiteConnection can be used to perform other data operations:
Getting an object by the primary key
SQLite.Net provides the Get method to retrieve a single object based on its primary key.
Selecting an object using Linq
Methods that return collections support
IEnumerable<T> so you can useLinq to query or sort the contents of a table. The following code showsan example using Linq to filter out all entries that begin with theletter 'A':
Selecting an object using SQL
Even though SQLite.Net can provide object-based access to your data,sometimes you might need to do a more complex query than Linq allows(or you may need faster performance). You can use SQL commands with theQuery method, as shown here:
Note
When writing SQL statements directly you create adependency on the names of tables and columns in your database, whichhave been generated from your classes and their attributes. If youchange those names in your code you must remember to update anymanually written SQL statements.
Deleting an object
The primary key is used to delete the row, as shown here:
You can check the
rowcount to confirm how many rows were affected(deleted in this case).
Using SQLite.NET with Multiple Threads
SQLite supports three different threading modes: Single-thread,Multi-thread, and Serialized. If you want to access the databasefrom multiple threads without any restrictions, you can configureSQLite to use the Serialized threading mode. It's important to setthis mode early in your application (for example, at the beginning ofthe
OnCreate method).
To change the threading mode, call
SqliteConnection.SetConfig . Forexample, this line of code configures SQLite for Serialized mode:
The Android version of SQLite has a limitation that requires a few moresteps. If the call to
SqliteConnection.SetConfig produces a SQLiteexception such as library used incorrectly , then you must use thefollowing workaround:
This workaround also works for the
Mono.Data.Sqlite library. For moreinformation about SQLite and multi-threading, seeSQLite and Multiple Threads.
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