Question

I have a table with 100 or more columns that could have a value “yes” or “no”.

I want to do a select according with the user’s request (checkbox values form) to extract all the rows that have the value at “yes”. So an example could be:

-User selects checkbox1 checkbox4 and checkbox7 and all the other are not selected.

The query could be:

select name from table where (col1 = yes or col4 = yes or col7 = yes) AND (col2= no and col3 = no and all the others columns are set to no)

How to implement this in an android query? And by the way this implementation that i found is not very elegant, could someone suggest me an other implementation for achieve that goal, please?

Answer 1

Here’s the fixed code. It contains some test code.

        int numColumns = 10;
        boolean[] answers = new boolean[numColumns];
        String[] colNames = new String[numColumns];
        for(int i = 0; i < colNames.length; i++) {
            answers[i] = Math.random() > 0.5;
            colNames[i] = String.format("Col%d", i);
        }
        //-----------LOGIC STARTS HERE----------------
        // use a loop
        StringBuilder yesColumns = new StringBuilder();
        StringBuilder noColumns = new StringBuilder();
        for(int i = 0; i < answers.length; i++) {
            if(answers[i]) {
                if(yesColumns.length() > 0)
                    yesColumns.append(" OR ");

                yesColumns.append(colNames[i]).append("='yes'");
            }
            else {
                if(noColumns.length() > 0)
                    noColumns.append(" AND ");
                noColumns.append(colNames[i]).append("='no'");
            }
        }

        String yesCondition = yesColumns.toString();
        String noCondition = noColumns.toString();
        String query = String.format("select name from table where (%s) AND (%s)",
                                     yesCondition,
                                     noCondition);
        System.out.println(query);
        // SQLiteDatabase db;
        // Cursor cursor = db.rawQuery(query, null);