sqlite - creating and upgrading data base in android -

i playing sqlite , android. far app has 2 activities..

a main activity:

import android.app.activity; import android.content.sharedpreferences; import android.database.sqlite.sqlitedatabase; import android.os.bundle; import android.util.log;  public class homefavesactivity extends activity {      private static final string tag = "homefavescatovoty";     sqlitedatabase lcdb;     /** called when activity first created. */     @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.main);          log.v(tag, "created");          databasemanager db = new databasemanager(this);         db.getwritabledatabase();       } } 

and databasemanager class:

import android.content.contentvalues; import android.content.context; import android.database.cursor; import android.database.sqlite.sqlitedatabase;  import android.database.sqlite.sqliteopenhelper; import android.util.log; import android.widget.toast;  public class databasemanager extends sqliteopenhelper{      private static final string tag = "databasemanager";     static final string dbname ="lcinstore";      static final string allicons = "icons";     static final string homeicons = "homescreenicons";      static final string coliconid = "iconid";     static final string colid = "id";     static final string colimage = "iconimage";     static final string collabel = "iconlabel";     static final string colname = "iconname";      public databasemanager(context context) {         super(context, dbname, null, 4); // starting value 1 must change on upgrades         log.v(tag, "initaited");         // todo auto-generated constructor stub     }      @override     public void oncreate(sqlitedatabase db) {         // todo auto-generated method stub         log.v(tag, "on create called");         // create icon table if not exist          db.execsql("create table "+ allicons +"" +                 "("+coliconid + " integer primary key autoincrement, "+                     colname + " text," +                     colimage + " text," +                     collabel + "text)");          // create homescreen icons table if not exist          db.execsql("create table if not exist " + homeicons+"" +                 "("+colid+" integer not null, foreign key ("+colid+") references " +                         ""+allicons+" ("+coliconid+"));");           inserticons(db);     }      @override     public void onupgrade(sqlitedatabase db, int oldversion, int newversion) {         // todo auto-generated method stub         log.v(tag, "on upgrade called");         db.execsql("drop table if exists "+allicons);         inserticons(db);      }      private void inserticons(sqlitedatabase db) {         contentvalues cv=new contentvalues();            cv.put(coliconid, 1);            cv.put(colname, "icon1");            cv.put(colimage, "icon_one");            cv.put(collabel, "one");            db.insert(allicons, coliconid, cv);             cv.put(coliconid, 2);            cv.put(colname, "icon2");            cv.put(colimage, "icon_two");            cv.put(collabel, "two");            db.insert(allicons, coliconid, cv);             cv.put(coliconid, 3);            cv.put(colname, "icon3");            cv.put(colimage, "icon_three");            cv.put(collabel, "three");            db.insert(allicons, coliconid, cv);             db.close();     }      public void addhomescreenicon(int id){         sqlitedatabase db=this.getwritabledatabase();         cursor c = db.rawquery("select * "+ homeicons +" colid = " +id, null);        int numfound = c.getcount();         if(numfound<1){            contentvalues cv=new contentvalues();            cv.put(colid, id);            db.insert(homeicons, colid, cv);        }         // else nothing       }      public void deletehomescreenicon (int id){         sqlitedatabase db=this.getwritabledatabase();         db.delete(homeicons, "id = " +id, null);         //         //need  find row of homeicons table matches id , delete         db.close();     }   } 

you noticed have 4 logs being created.. 1 in main activity' on create, 1 in databasemanager's constructor, oncreate, , onupgrade using these logs try , see when database created , or upgraded ect.. far logs fire homefavesactivity , 1 in constructor of databasemanager. other 2 not firing. how create database, , how upgrade should want to?

exception error:

03-07 12:06:33.459: d/androidruntime(1257): shutting down vm 03-07 12:06:33.459: w/dalvikvm(1257): threadid=1: thread exiting uncaught exception (group=0x401df760) 03-07 12:06:33.459: e/androidruntime(1257): fatal exception: main 03-07 12:06:33.459: e/androidruntime(1257): java.lang.runtimeexception: unable start activity componentinfo{com.sapient/com.sapient.homefavesactivity}: android.database.sqlite.sqliteexception: near "exist": syntax error 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.activitythread.performlaunchactivity(activitythread.java:1751) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.activitythread.handlelaunchactivity(activitythread.java:1767) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.activitythread.access$1500(activitythread.java:122) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.activitythread$h.handlemessage(activitythread.java:1005) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.os.handler.dispatchmessage(handler.java:99) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.os.looper.loop(looper.java:132) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.activitythread.main(activitythread.java:4028) 03-07 12:06:33.459: e/androidruntime(1257):     @ java.lang.reflect.method.invokenative(native method) 03-07 12:06:33.459: e/androidruntime(1257):     @ java.lang.reflect.method.invoke(method.java:491) 03-07 12:06:33.459: e/androidruntime(1257):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:844) 03-07 12:06:33.459: e/androidruntime(1257):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:602) 03-07 12:06:33.459: e/androidruntime(1257):     @ dalvik.system.nativestart.main(native method) 03-07 12:06:33.459: e/androidruntime(1257): caused by: android.database.sqlite.sqliteexception: near "exist": syntax error 03-07 12:06:33.459: e/androidruntime(1257):     @ android.database.sqlite.sqlitestatement.native_executesql(native method) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.database.sqlite.sqlitestatement.executeupdatedelete(sqlitestatement.java:89) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.database.sqlite.sqlitedatabase.executesql(sqlitedatabase.java:1933) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.database.sqlite.sqlitedatabase.execsql(sqlitedatabase.java:1864) 03-07 12:06:33.459: e/androidruntime(1257):     @ com.sapient.databasemanager.oncreate(databasemanager.java:45) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.database.sqlite.sqliteopenhelper.getwritabledatabase(sqliteopenhelper.java:157) 03-07 12:06:33.459: e/androidruntime(1257):     @ com.sapient.homefavesactivity.oncreate(homefavesactivity.java:22) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1048) 03-07 12:06:33.459: e/androidruntime(1257):     @ android.app.activitythread.performlaunchactivity(activitythread.java:1715) 03-07 12:06:33.459: e/androidruntime(1257):     ... 11 more 

you enter in methods when call either getwritabledatabase() or getreadabledatabse() on databasemanager instance db.

db.getwritabledatabase(); 

or

db.getreadabledatabase();