SQL SELECT & UPDATE Syntax

Question

I'm trying to do a SELECT and a UPDATE in SQL, using a single Statement. After some Google FU i can't seem to find any documentation on it. Or maybe i'm looking for the wrong thing.

inquirer
        .prompt([{
            name: "updateID",
            type: "input",
            message: "What's the ID of the product you'd like to update?"
        },
        {
            name: "updateQuantity",
            type: "input",
            message: "How many units would you like to add to inventory?"
        }]).then(function(answer) {
            connection.query("SELECT id, stock_quantity FROM products WHERE ?", 
            {
                id: parseInt(answer.updateID)
            }, function(err, res) {

            })

        })

I'd hope there's a way to do a SELECT and UPDATE in a single statement.

Answer 1

Unless you specifically want to read the data for that product, you don't need to do a SELECT before you UPDATE the value. Based on your code, this query should do what you want:

UPDATE products
SET stock_quantity = stock_quantity + ?
WHERE id = ?

If you do want to read the data as well, you have to perform separate SELECT and UPDATE queries.

Answer 2

I want to SELECT a row in the table by the ID, then UPDATE one the values in a column of that row...

In order to update only certain rows, you can use a single UPDATE query with a WHERE clause.

UPDATE <table> SET <column>=<value>
WHERE <id_column>=<id>;