android - How to initiate the call onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)? -


i need upgrade android sqlite database version 1 version 2. not understand how call public void onupgrade(sqlitedatabase db, int oldversion, int newversion)is initiated? how , when method called? don't understand pass version number 2?

[edit] think need clarify question. here class:

public class mysqliteopenhelper  extends sqliteopenhelper {   public mysqliteopenhelper(context context){     super(context,             constants.db_name,             null,             1); }  public mysqliteopenhelper(context context, int version){     super(context, constants.db_name, null, version); }  public mysqliteopenhelper(context context, string name,                                cursorfactory factory, int version) {     super(context, constants.db_name, factory, version);     // todo auto-generated constructor stub }  public mysqliteopenhelper(context context, string name,                                cursorfactory factory, int version,                                databaseerrorhandler errorhandler) {     super(context, constants.db_name, factory, version, errorhandler);     // todo auto-generated constructor stub } public void oncreate(sqlitedatabase db) {     // creation stuff } public void onupgrade(sqlitedatabase db, int oldversion, int newversion) {     // upgrade stuff } }

so, how android trigger onupgrade?

the sqliteopenhelper constructor takes name , version number, , helper invoke oncreate or onupgrade callback necessary. need maintain database version numbers yourself, bumping version number when schema change necessary.

when need update database version 1 version 2 change

super(context, constants.db_name, null, 1);

to

super(context, constants.db_name, null, 2);

then in onupgrade method drop tables, add tables, or else needed upgrade 1 2. onupgrade invoked first time sqliteopenhelper instantiated after version number changes.


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