Question

Beginner’s question: I’m trying to manipulate tuples from two different attributes in a relation using Java to process the SQL (for a university non-assessed practical).
I have a relation with four attributes, including the name of a type of coffee, the sales it has that week and the total sales of the coffee.

The code I am trying to create will update the sales and the total fields with new figures. It is meant to take both totalSales and Sales arrays, add them, then update both attributes in the relation accordingly.

This is my code so far (I’ve cut out all obvious/unnecessary code):

String updateTotalString = "update COFFEES set TOTAL = ? set SALES = ? where COF_NAME = ?";

String [] coffees = {"Columbian", "Earl Grey", "Kenyan", "Nescafe"};
int [] totalSales = {400,650,340,1000};
int[] sales = {50,75,100,100};

updateTotal = con.prepareStatement(updateTotalString);
    for (int i = 0; i < len; i++)
    {
        updateTotal.setInt(1, (sales[i] + totalSales[i]));
        updateTotal.setInt(2, sales[i]);
        updateTotal.setString(3, coffees[i]);
        updateTotal.executeUpdate();
    }

Unfortunately, running this gives me an SQL syntax error, focusing on the first line (the String updateTotalString). I have a feeling it’s to do with the fact I’m trying to do two sets in one line and have got the syntax wrong.
Can anybody help me out?

Answer 1

use , instead of multiple SET

String updateTotalString = "update COFFEES set TOTAL = ?, SALES = ? where COF_NAME = ?";

the basic syntax of update is

UPDATE tableName
SET colA = '',
    colB = '', .....
WHERE ....