QT SQL query loop?

Reply to QT SQL query loop? on Sun, 12 Aug 2018 15:42:04 GMT

JonB — Sun, 12 Aug 2018 15:42:04 GMT

@davethedave
Firstly, I don't work in C++ so I don't test the code for the right way to pass the output string to printf(). So your corrections are good. [BTW you'd be better off not using printf() and using Qt/C++ functions, then you wouldn't have all that toUtf8().constData() stuff, but that's another matter.]

As you can see you have 3 rows matching the query, you tell us you have 5, or you had 5 and now you have 3. That's worrying when you're asking for help. Your Username value appears to be 1 from the output. That is a strange username. I don't know what your problem is. The original code should correctly print out whatever is in the Username column of each row encountered (note that since you didn't put a \n in it will all come on one line, which isn't great, I do trust that is not what this is all about.)

Reply to QT SQL query loop? on Sun, 12 Aug 2018 15:25:18 GMT

davethedave — Sun, 12 Aug 2018 15:25:18 GMT

@JonB said in QT SQL query loop?:

query.exec("SELECT * FROM users");

from the first:
http://prntscr.com/khp72u

if i append
.toUtf8().constData() then the below
http://prntscr.com/khp79y

from the second:
http://prntscr.com/khp72u

if i append
.toUtf8().constData() then the below
http://prntscr.com/khp7tw

Also there is only 3 rows now

Reply to QT SQL query loop? on Sun, 12 Aug 2018 15:13:35 GMT

JonB — Sun, 12 Aug 2018 15:13:35 GMT

@davethedave
Please show output of each of the 2 following:

query.exec("SELECT COUNT(*) FROM users");
while (query.next())
{
    printf("Number: %s\n", query.value(0).toString());
}

query.exec("SELECT * FROM users");
while (query.next())
{
    printf("Username: %s\n", query.value(0).toString());
}

Reply to QT SQL query loop? on Sun, 12 Aug 2018 11:56:29 GMT

davethedave — Sun, 12 Aug 2018 11:56:29 GMT

@JonB
Prints first entry in the table still.

Reply to QT SQL query loop? on Sun, 12 Aug 2018 10:35:27 GMT

JonB — Sun, 12 Aug 2018 10:35:27 GMT

@davethedave

query.exec("SELECT * FROM users");
while (query.next())
{
    printf("Usernames: %s", query.value("Username").toString());
}

Reply to QT SQL query loop? on Sun, 12 Aug 2018 10:32:53 GMT

davethedave — Sun, 12 Aug 2018 10:32:53 GMT

Hello, I have 5 entries
query.exec("SELECT * FROM users");
if (query.size() > 0)

and its the only check i could think of

Reply to QT SQL query loop? on Sat, 11 Aug 2018 18:50:44 GMT

SGaist — Sat, 11 Aug 2018 18:50:44 GMT

Hi,

How many entries do you have in that table ?
What query did you use ?
Why are you doing this complex check in the while condition ?