Counting records in a QSqLite db

gabor53

Hi,
I have a QSqLite db and I need to find out the number of records in one of the tables. I currently have the following code, which says I have only one record (the correct number would be 7):

  while (query_fix.next () == true) {
    recCount++;
    query_fix.next ();
  }
  qDebug() << "Record count (fixdb): " << recCount;

What did I miss?
Thank you for your help.

Yashpal

@gabor53 said in Counting records in a QSqLite db:

query_fix.next ();

Why are you having query_fix.next (); inside while loop? Remove them, post that you should record count correctly.

Venkatesh V

@gabor53
Hi,
try this query,
SELECT Count(*) FROM TableName;

gabor53

@Venkatesh-V
I tried like this:

recCount =  query_fix("SELECT COUNT(*) FROM Items");

and I got the following error message:
C:\Programming\Projects\Folkfriends_bzr\checkout\fixdb.cpp:121: error: no match for call to '(QSqlQuery) (const char [27])'
recCount = query_fix("SELECT COUNT(*) FROM Items");
^
Any idea why?

SGaist

Hi,

Because that's not how you use a QSqlQuery object.

A select count should be handled the same as classic select call. You'll just have one result which will contain the number of rows.

gabor53

@SGaist
Hi,
Is this supposed to work on QSqLite?

Venkatesh V

@gabor53
Hi,

int recCount = query_fix.prepare("SELECT COUNT(*) FROM Items");
query_fix.exec();

SGaist

@gabor53 What is supposed to work ?

gabor53

@SGaist
select count with QSqLite.

gabor53

@Venkatesh-V
This returns 1, but there are 7 records in the db. Any idea why?

 int recNum;
  recNum = query_fix.prepare ("SELECT COUNT(*) FROM Items");
  query_fix.exec ();

  qDebug() << "Record count in fixdb: " << recNum;

mrjj

hi
If i show you how the function is defined, can you then guess why its 1 ?
bool QSqlQuery::prepare(const QString & query)

I will give you a hint and say that
query_fix.exec ();
must be used.
Also the value of true is often 1.

gabor53

@mrjj
Thank you.Now I understand why it is 1. How can I get around it?

Venkatesh V

@gabor53

Hi,
Try this,

int recNum =0;
query_fix.prepare ("SELECT * FROM Items");
if( query_fix.exec ()){
while( query.next() )
{
recNum ++;
}
}
qDebug() << "Record count in fixdb: " << recNum;

Venkatesh V

Or you can also use this,

QSqlQuery q;
q.prepare("SELECT COUNT (*) FROM TableName");
q.exec();
int rows= 0;
if (q.next()) {
rows= q.value(0).toInt();
}

gabor53

@Venkatesh-V
This worked.
Thank you.