Question

I am having problems writing statements, especially when updating.

• I want to update a column with a parameter, but I don’t know the special characters to use like @ or %d.

I tried to do:

const char *sqlStatement = [[NSString stringWithFormat:
  @"update lugar set frecuencia ='d%'aumentador Where idLugar = '%d'",
  idLugarParametro] cStringUsingEncoding:NSUTF8StringEncoding];

But I get a problem with: frecuencia ='d%'aumentador

• How can I find a guide or tutorial for using this special characters for creation statements? (Using Objective C specifically.)

Answer 1

Here’s An Introduction To The SQLite C/C++ Interface.

Here’s the Apple documentation for NSString stringWithFormat, and string format specifiers.

I note that it seems you typed d%, but probably meant %d for the format specifier (you might need an extra space in there too), and that
you’ve only supplied one arg (idLugarParametro), but your format string has two specifiers:

------------------------------1v------------------------------2v
update lugar set frecuencia ='%d' aumentador Where idLugar = '%d'

so you need to supply two values – the new frecuencia value is not there.

Lastly, suggest that you look in to the use of prepared statements once you’ve got the hang of the basics – see the SQLite docs.