Question

I need to dynamically change tables and variables from time to time, so I wrote a python method like this:

    selectQ ="""SELECT * FROM  %s WHERE %s = %s;""" 
    self.db.execute(selectQ,(self.table,self.columnSpecName,idKey,))
    return self.db.store_result()

However this results in a syntax error exception. I tried debugging it so I printed the variables in the method and filled them in manually, and that worked. So I am not sure what I am doing wrong ?

Is it because I try to use a substitute for a table ?

Also how do I debug mysqldb so it prints the substituted query as a string ?

Answer 1

Parameter substitution in the DB API is only for values – not tables or fields. You’ll need to use normal string substitution for those:

selectQ ="""SELECT * FROM  %s WHERE %s = %%s;""" % (self.table,self.columnSpecName)
self.db.execute(selectQ,(idKey,))
return self.db.store_result()

Note that the value placeholder has a double % – this is so that it’s left alone by the initial string substitution.