Hi,

Just started using mysql++ today for the first time. I went through
the examples and they worked fine.

I tried to make a generic function=20

Result Select_From_Database ( const char* field_select, const char*
table_name, const char* field_name, const char* field_value)

My setup looks soemthing like this:

Result Select_From_Database ( const char* field_select, const char*
table_name, const char* field_name, const char* field_value)
{
Connection con(use_exceptions);
=09try {
=09=09con.real_connect(MY_DATABASE, MY_HOST, MY_USER, MY_PASSWORD, 3306,
=09=09=09=09=09=09 0, 60, NULL);
=09=09// Create a query object that is bound to con.
=09=09Query query =3D con.query();
=09=09// reset the query object when re-using it.
=09=09query.reset();
=09=09=09=09=09=09
=09=09query << "SELECT " << field_select << " FROM " << table_name << "
WHERE " << field_name << " =3D '" << field_value <<"'";
=09=09=09=09
=09=09Result res =3D query.store();
=09=09=09 =09=09=09=09
=09=09return res;
=09=09=09
=09}
// catch exceptions
}

and I have another function :

char* validate(const char* userlevel, const char* password)=20
{=20
=09Result res =3D Select_From_Database ( "password", "access",
"userlevel", userlevel);
=09
=09=09
=09if ( strcmp(password, res[0][0]) =3D=3D 0 ) {
=09 =09=09=09=09=09=09
=09=09char* access =3D createUserObject(userlevel);=09=09
=09=09=09=09
=09=09return access; // Grants access
=09}
=09else {
=09=09cout << "Login was not Succesfull " << endl;
=09=09return "-1"; // Access NOT GRANTED
=09}=09
}

Something really weird happens, in the Select_From_Database, the res
object size , res.size() is 1 (1 Record found)

but when I pass it on to validate the size becomes 134722808. The
result I'm looking for is still stored in the new res variable
res[0][0] and I can access it fine but after I finish executing the
validate function I get a Segmentation Error and the program shuts
down????

Would really appreciate some help with this !

Thanks in advance,

Roland

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On Mon, May 30, 2005 at 11:46:05AM +0000, Roland Sgorcea wrote:
Your connection should live for the entire data-using session. In this
code, connection disappears when the function exits. The result still
depends on it.

You might wish to reorganize your code so that your connection is in main(),
and Select_From_Database takes a reference to it as an argument.

Or organize your database functions in a class, the class containing the
connection.

- Chris


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Roland Sgorcea wrote:

In addition to what Chris said, you should consider passing a reference
to the result object to the function, or some other way to prevent this
copy. Result is not a light-weight object...returning it by value is
very wasteful.

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