Using variables to insert data into SQL Server 2008

QT problems with data insertion through ODBC connection to database SQL Server 2008:

How do I use variables to insert data into variables? How do I write the INSERT statement?

Qsqlquery query (DB);

Query.exec ("INSERT into device values", "+datetime+" ', ' "+splantnum+" ', ' "+sdevicenum+" ', ' "+stemper+" ', ' "+spress+", ' "+sflow+");

Note the correct use of quotation marks: internal double quotation marks, external single quotation marks. and the variable between + + is of type qstring.