Check whether database is empty

Question

I am trying to check if a sqlite database is empty using

public boolean chkDB(){
        boolean chk = false;
        Cursor mCursor = db.rawQuery(\"SELECT          


        

Answer 1

In Kotlin you can do just that

package myapp.package.name
import android.content.Context

class SQLiteDatabaseCrud(context: Context) {
    private val dbHelper: DBHelper = DBHelper(context)
    private var chk = false
    fun isEmpty(): Boolean? {
        val db = dbHelper.readableDatabase
        val cursor = db.rawQuery("SELECT * FROM " + Business.TABLE, null)
        chk = if (cursor != null){
            cursor.moveToFirst()
            cursor.count != 0
        }else{
            true
        }
        cursor.close()
        return chk
    }
}

So in your activity you just call the function

 private var mSQLiteDatabaseCrud: SQLiteDatabaseCrud? = null

 mSQLiteDatabaseCrud = SQLiteDatabaseCrud(applicationContext)
    if(mSQLiteDatabaseCrud?.isEmpty()!!){
        Toast.makeText(applicationContext,"database is not empty", Toast.LENGTH_SHORT).show()       
    }else{
        performRequest()
        Toast.makeText(applicationContext,"empty database", Toast.LENGTH_SHORT).show()
    }

Answer 2

I know this is too late ,but i had the same error before and order to fix it change your code to:

public boolean chkDB(){
        boolean chk = false;
        Cursor mCursor = db.rawQuery("SELECT * FROM " + DATABASE_TABLE, null);
        if (mCursor != null){
           while(mCursor.moveToFirst()){
           if (mCursor.getInt(0) == 0){
                chk = false;
            }
        }else{
            chk = true;
        }

}
           
        return chk;
    }

You have to add while statement not if or else it will cause a IndexOutOfBound exception

Answer 3

if(mCursor!=null&&mCursor.getCount>0)

Answer 4

if(mCursor.getCount() == 0) 

should do the trick

Answer 5

Set up a query-method (either in your ContentProvider directly) or in another class using your ContentResolver with a projection for one column (ID should do the trick). Then see if the cursor contains anything or not.

I did this outside the ContentProvider in a task class:

//Is database empty?
public static boolean isDbEmpty(Context context) {
    ContentResolver contentResolver = context.getContentResolver();

    String[] projection = new String[] {#_ID#};

    Cursor csr = checkResolver.query(#CONTENT_URI#, projection, null,
            null, null);
    if (csr != null && csr.moveToFirst()) {
        csr.close();
        return  false;
    } else {
        return true;
    }
}

Answer 6

mCursor.moveToFirst() Returns a boolean of whether it successfully found an element or not. Use it to move to the first row in the cursor and at the same time check if a row actually exists.

Cursor mCursor = db.rawQuery("SELECT * FROM " + DATABASE_TABLE, null);
Boolean rowExists;

if (mCursor.moveToFirst())
{
   // DO SOMETHING WITH CURSOR
  rowExists = true;

} else
{
   // I AM EMPTY
   rowExists = false;
}

You are trying to access a row in the cursor regardless of whether one exists or not.