QSqlQuery - Prepare fails with 'Parameter count mismatch'

Question

The following code creates a table and stuffs the database with data. When running the below code, I receive an error 'Parameter count mismatch' on query.exec(). However, if I use the commented line instead, everything works fine. How am I misusing the prepare feature?

QSqlQuery query;
if (query.exec("CREATE TABLE Users ( u_ID INT IDENTITY(1,1) PRIMARY KEY, cName varchar(25) UNIQUE )"))
{
    for (int i=1;i<=100;++i)
    {
        QString uName;
        uName = "user" + QString::number(i);
        query.prepare("INSERT INTO Users (cName) VALUES(':UNAME')");
        query.bindValue(":UNAME",uName);
        query.exec();
        //query.exec("INSERT INTO Users (cName) VALUES('"  + uName +  "')");
        if (query.lastError().isValid()){
            QMessageBox::information(0,"ERR!",query.lastError().text());
        }
    }
}

Mat · Accepted Answer · 2012-01-08 18:53:23Z

6

Just use:

query.prepare("INSERT INTO Users (cName) VALUES(:UNAME)");

i.e. don't quote bind variables.

answered Jan 8, 2012 at 18:53

Mat

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3 Comments

MatBailie Over a year ago

+1 : The ' around strings, strings escaping, and all other type considerations are all dealt with for you in parameterised queries.

Serodis Over a year ago

So, using prepare is safe for 'raw' user-data?

Mat Over a year ago

Yes, if you use bind variables as you do here.

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