How to get row cursor with primary key android-CodePudding

I have a table with the following

@Override
public void onCreate(SQLiteDatabase database) {
    database.execSQL( "CREATE TABLE "   TABLE_NAME   " ("   "ID"   " INTEGER PRIMARY KEY,"  
        COLUMN_TOPIC   " TEXT,"   COLUMN_LOCATION   " TEXT)");
}

I am trying to get all the data at a given rowid

public void getRowCursor(int position){
    SQLiteDatabase database = getWritableDatabase();
    
    Cursor cursor = database.rawQuery("SELECT * FROM "   TABLE_NAME   " WHERE "  
                "ID"   "="   String.valueOf(position), null);
    cursor.moveToFirst();
    cursor.close
    //or
    
    Cursor cursor = database.query(TABLE_NAME, null, "ID", new String[]{
        String.valueOf(position)},  null, null, null, null );
    cursor.moveToFirst();
    cursor.close
    database.close
}

I get an error

java.lang.IllegalArgumentException: Cannot bind argument at index 1 because the index is out of range.  The statement has 0 parameters.

I did populate the table. How do I return a cursor based on the position of entry.

CodePudding user response：

How do I return a cursor based on the position of entry

First, your method getRowCursor() should return a Cursor.
Also, you should not close the returned cursor because I assume that you want to use its results somehow.

Your code with the method rawQuery() should work like this:

public Cursor getRowCursor(int position) {
    SQLiteDatabase database = getWritableDatabase();
    String sql = "SELECT * FROM "   TABLE_NAME   " WHERE ID = "   String.valueOf(position);
    Cursor cursor = database.rawQuery(sql, null);
    // cursor.moveToFirst();
    return cursor;
}

But, the safe and recommended way to pass parameters to a query is with ? placeholders instead of concatenating them inside the sql statement and passing them as array items in the 2nd argument of rawQuery():

public Cursor getRowCursor(int position) {
    SQLiteDatabase database = getWritableDatabase();
    String sql = "SELECT * FROM "   TABLE_NAME   " WHERE ID = ?";
    Cursor cursor = database.rawQuery(sql, new String[] {String.valueOf(position)});
    // cursor.moveToFirst();
    return cursor;
}

Note that moveToFirst() moves the cursor's index at the 1st row of the cursor (if it exists).
I commented out this call, because you should use it after you call getRowCursor() like this:

Cursor cursor = getRowCursor(10); // or any other ID
if (cursor.moveToFirst()) {  // the cursor contains at least 1 row
    ....
} else {  // the cursor is empty
    ....
}

and when you are done with the cursor:

cursor.close();