{"id":163,"date":"2017-04-09T12:53:15","date_gmt":"2017-04-09T12:53:15","guid":{"rendered":"http:\/\/abhiandroid.com\/database\/?p=163"},"modified":"2018-06-06T05:26:46","modified_gmt":"2018-06-06T05:26:46","slug":"operation-sqlite","status":"publish","type":"post","link":"https:\/\/abhiandroid.com\/database\/operation-sqlite.html","title":{"rendered":"Insert, Read, Delete & Update Operation In SQLite"},"content":{"rendered":"

Android provides different ways to store data locally so using SQLite is one the way to store data. SQLite is a structure query base database, hence we can say it\u2019s a relation database. 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 android.database.sqlite packages.<\/p>\n

While using SQLite there could be two different ways to perform different operations like create, read, update and delete. One writing raw queries and another is using parameterized functions or we can say parametrized queries.
\n\"SQLite
\nCreate:<\/strong><\/span> Creating a database is very simple in android by using SQLiteOpenHelper class. 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. Whenever we need to create a database we have to extend SQLiteOpenHelper class as follows:<\/p>\n

\/**A helper class to perform database related queries*\/\r\n\r\npublic class SqliteManager extends SQLiteOpenHelper {\r\npublic static final String DATABASE_NAME = \"abhiandroid.db\";\r\npublic static final int version = 1;\r\n \r\npublic SqliteManager(Context context) {\r\n   super(context, DATABASE_NAME, null, version);\r\n  }\r\n\r\n@Override\r\npublic void onCreate(SQLiteDatabase sqLiteDatabase) {\r\n   String dbQuery = \"CREATE TABLE Items (id INTEGER PRIMARY KEY                          \r\n   AUTOINCREMENT,name TEXT, description TEXT)\";\r\n   sqLiteDatabase.execSQL(dbQuery);\r\n  }\r\n\r\n@Override\r\npublic void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {\r\n  }\r\n}<\/pre>\n
onCreate(SQLiteDatabase sqLiteDatabase)<\/span><\/strong> method is called only for once throughout the application lifecycle, it will be called whenever there is first call to getReadableDatabase() or getWritableDatabase() function available in super SQLiteOpenHelper class so SQLiteOpenHelper class call the onCreate() method after creating database and instantiate SQLiteDatabase object. Database name is passed in constructor call.<\/p>\n
onUpgrade(SQLiteDatabase db,int oldVersion, int newVersion)<\/span><\/strong> is only called whenever there is a updation in existing version so to update a version we have to increment the value of version variable passed in the superclass constructor. In onUpgrade method we can write queries to perform whatever action is required. In most example you will see that existing table(s) are being dropped and again onCreate() method is being called to create tables again. But it\u2019s not mandatory to do so it all depends upon your requirements. We have to change database version if we have added a new row in the database table in this case if we have requirement that we don\u2019t want to lost existing data in the table then we can write alter table query in the onUpgrade(SQLiteDatabase db,int oldVersion, int newVersion) method.<\/p>\n
Likewise if there is no requirement of existing data whenever we upgrade database version then we can write drop table query in onUpgrade(SQLiteDatabase db,int oldVersion, int newVersion) method and call onCreate(SQLiteDatabase sqLiteDatabase) method again to create table again. Remember never call onCreate(SQLiteDatabase sqLiteDatabase) method if you have written alter table query in onUpgrade(SQLiteDatabase db,int oldVersion, int newVersion) method.<\/p>\n
\n
Insert, Read, Delete & Update Operation In Sqlite:<\/b><\/h4>\n
To perform insert, read, delete, update operation there are two different ways:<\/p>\n