NodeJS MySQL query gives 'undefined' rows

Question

I'm using mysql with nodeJS and creating a query. The rows I get for the query are 'undefined'. This has never happened to me before, and I'm stumped.

 // check if URL already exists in database connection.query("SELECT * FROM shorturl WHERE urlsource='?'", [url], function(error, rows, fields){ if (error) { console.log(error); } if (rows.length == 0) { console.log(rows); //prints 'undefined' insertURL(); } else { console.log("creating new entry"); printURL(); } });

Are you sure that it is really the console.log(rows); that prints undefined? This does not make sense, because then the rows.length would throw a cannot read property length of undefined error. — t.niese
– t.niese, Commented Sep 30, 2016 at 18:47
Oh, I modified the code later. Yes, I get the "cannot read property length of undefined" error first — Human Cyborg Relations
– Human Cyborg Relations, Commented Sep 30, 2016 at 19:58
And are you sure that console.log(error); does not log an error. You should wrap all of the code below if (error) { console.log(error); } in the else block of the if (error). — t.niese
– t.niese, Commented Sep 30, 2016 at 20:01
My guess is that you're getting an error because of the quotes around the placeholder in the query (... WHERE urlsource = '?'). — robertklep
– robertklep, Commented Sep 30, 2016 at 20:05

angvee · Accepted Answer · 2016-10-03 07:59:48Z

you can try this, a result from query connection NodeJS is array. Try to add rows[0] hope this will help.

if (rows[0].length == 0) { console.log(rows[0]); insertURL(); } else { console.log("creating new entry"); printURL(); }

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