Re: [sqlite] Error:"Expression cannot be evaluated" withsqlite3_exec()

[Alberto Tellaeche]

Hello Igor;

I have modified the code to avoid string writting problems now, it is:

int ActualizarBBDDAlumnos(char *dni, float nota)
{
char *errorMsg;

char *orden_SQL = sqlite3_mprintf("update ALUMNO set nota=%0.1f where 
dni=%Q;",nota,dni);
sqlite3_exec(db,orden_SQL,0,0,);
sqlite3_free(errorMsg);
sqlite3_free(orden_SQL);
return(0);
}

after sqlite3_mprintf() function, I obtain the string like this: " update 
ALUMNO set nota=0.2 where dni='12345678J' "
After sqlite3_exec() errorMsg=NULL (0x Bad ptr), and the command is not 
exectuted in table ALUMNO, the value is not changed.
If I type exactly the same order from the sqlite3 command line, it works 
perfectly.

The database and tables where created folloeing the examples in 
http://www.sqlite.org/sqlite.html ,with CREATE TABLE commands and INSERT INTO 
TABLE commands.

I still don´t understand what is happening, so, as always, thank you very much.

Regards,

Alberto



- Mensaje original 
De: Igor Tandetnik <[EMAIL PROTECTED]>
Para: sqlite-users@sqlite.org
Enviado: miércoles, 15 de octubre, 2008 22:18:48
Asunto: Re: [sqlite] Error:"Expression cannot be evaluated" withsqlite3_exec()

Alberto Tellaeche <[EMAIL PROTECTED]>
wrote:
> Tank you very much for the response.
> the array is as expected, sprintf is woking fine. Also I get the same
> error if I write the SQL command directly in the sqlite3_exec()
> function, so this is not the error...

Show the CREATE TABLE statement for ALUMNO table. Show the exact text of 
the statement you run, after sprintf.

Igor Tandetnik 



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Re: [sqlite] Error:"Expression cannot be evaluated" with sqlite3_exec()

[Alberto Tellaeche]

Tank you very much for the response.
the array is as expected, sprintf is woking fine. Also I get the same error if 
I write the SQL command directly in the sqlite3_exec() function, so this is not 
the error...

Thank you again for the interest,

Regards

alberto



- Mensaje original 
De: Igor Tandetnik <[EMAIL PROTECTED]>
Para: sqlite-users@sqlite.org
Enviado: miércoles, 15 de octubre, 2008 17:31:59
Asunto: Re: [sqlite] Error:"Expression cannot be evaluated" with sqlite3_exec()

Alberto Tellaeche <[EMAIL PROTECTED]>
wrote:
> work perfectly well, but I am having a very annoying problem with
> sqlite3_exec() function. The code just after the example above is:
>
>memset(orden_SQL,0,200*sizeof(char));
>sprintf(orden_SQL,"update ALUMNO set nota=%0.1f where
>dni='%s';",nota,dni);
>res=sqlite3_exec(db,orden_SQL,0,0,);
>sqlite3_free(errorMsg);

Examine orden_SQL after sprintf, check that it's as expected. For 
example, sprintf is locale sensitive: if your locale, say, uses comma 
for decimal separator rather than a period, the query would end up with 
something like "set nota=1,1". But SQLite expects to see a period for 
decimal separator.

Igor Tandetnik



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[sqlite] Error:"Expression cannot be evaluated" with sqlite3_exec()

[Alberto Tellaeche]

Hello colleagues;

I am new to sqlite, and I have recently started to use it from the command line 
(sqlite3.exe) and in C programs.

In my C example program I open de database at the beginning and close it 
beforte the end of the program.
 Examples like:

memset(orden_SQL, 0, 200*sizeof(char));
sprintf(orden_SQL,"select nBlancos from CORRECCION_EXAMEN where 
modelo='%c';",modelo);
sqlite3_get_table(db,orden_SQL);
for(i=1;i<=Rows;i++)
{
examen.blancos[i-1]=atoi(Resultado[i]);
}

work perfectly well, but I am having a very annoying problem with 
sqlite3_exec() function. The code just after the example above is:

memset(orden_SQL,0,200*sizeof(char));
sprintf(orden_SQL,"update ALUMNO set nota=%0.1f where dni='%s';",nota,dni);
res=sqlite3_exec(db,orden_SQL,0,0,);
sqlite3_free(errorMsg);


and it does not work. "res" value is 0 and "errorMsg" is Error:"Expression 
cannot be evaluated".

I have also tried to substitute sqlite3_exec with sqlite3_prepare() + 
sqlite3_step() with the same result.
The command "update ALUMNO set nota=9 where dni='12345678P';" works perfect in 
the comand line.

What problem I am having here? It is very important for me for the project I am 
developping, so I would appreciate a lot any kind of advise.

Best regards,

Alberto



  
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