loadnoob.blogg.se - Simple sqlite database example in android

#SIMPLE SQLITE DATABASE EXAMPLE IN ANDROID UPDATE#
#SIMPLE SQLITE DATABASE EXAMPLE IN ANDROID UPGRADE#
#SIMPLE SQLITE DATABASE EXAMPLE IN ANDROID ANDROID#

It passes us a SQLiteDatabase object, pointing to a newly-created database, that we can populate with tables and initial data. onCreate(SQLiteDatabase db) : It’s called when there is no database and the app needs one.Super(context, DB_NAME, null, DB_VERSION) Constructor : This takes the Context (e.g., an Activity), the name of the database, an optional cursor factory (we’ll discuss this later), and an integer representing the version of the database schema you are using (typically starting from 1 and increment later).For that we’ll need to create a custom subclass of SQLiteOpenHelper implementing at least the following three methods.

#SIMPLE SQLITE DATABASE EXAMPLE IN ANDROID UPGRADE#

SQLiteOpenHelper wraps up these logic to create and upgrade a database as per our specifications. We will have option to alter the database schema to match the needs of the rest of the app.

When the application is upgraded to a newer schema – Our database will still be on the old schema from the older edition of the app.

So we will have to create the tables, indexes, starter data, and so on.

When the application runs the first time – At this point, we do not yet have a database.

if distinct is passed as true Cursor data set will not have any duplicate row.SQLiteOpenHelper is designed to get rid of two very common problems. Most of the parameters in query overloaded functions are optional except from table and distinct any of other parameters can be passed as null.

public Cursor query (boolean distinct, String table, String columns, String selection, String selectionArgs, String groupBy, String having, String orderBy, String limit).

public Cursor query (String table, String columns, String selection, String selectionArgs, String groupBy, String having, String orderBy).public Cursor query (String table, String columns, String selection, String selectionArgs, String groupBy, String having, String orderBy, String limit).It returns Cursor object so Cursor is a result-set with queried data, it provides different functions really helpful while reading data.įollowing are some overloaded query functions: query() method is overloaded with different set of parameters. SQLiteDatabase class provides query() method to read data from table. Read(select):Reading from a database table is bit different from other functions like insert,update and delete. Important Note: If you want to remove all rows and require count of deleted ones also then pass 1 as whereClause. delete function will return number of affected row if whereClause passed otherwise will return 0.

Here whereClause is optional, passing null will delete all rows in table. Public class SqliteManager extends SQLiteOpenHelper ĭb.delete( "Items", whereClause, whereArgs) Whenever we need to create a database we have to extend SQLiteOpenHelper class as follows: /**A helper class to perform database related queries*/ SQLiteOpenHelper is an abstract class with two abstract methods onCreate(SQLiteDatabase db) and onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) and many more database helpful functions.

#SIMPLE SQLITE DATABASE EXAMPLE IN ANDROID ANDROID#

One writing raw queries and another is using parameterized functions or we can say parametrized queries.Ĭreate: Creating a database is very simple in android by using SQLiteOpenHelper class.

#SIMPLE SQLITE DATABASE EXAMPLE IN ANDROID UPDATE#

While using SQLite there could be two different ways to perform different operations like create, read, update and delete. Android os has its own implementation to perform CRUD (Create, Read, Update, Delete)operations, so Android provides set of classes available in android.database and packages. SQLite is a structure query base database, hence we can say it’s a relation database. Android provides different ways to store data locally so using SQLite is one the way to store data.