如何在C ++ Builder 10.2中将查询转换为参数查询

Question

I have "normal" string query

String sqlquery = Format("select * from events where location = %d",ARRAYOFCONST(parameter_value));

how to convert this query into a parametric one in C++ Builder 10.2 (i use postgres database)

Answer 1

Per the TPSQLQuery.SQL property documentation:

The SQL statement in the SQL property may contain replaceable parameters, following standard SQL-92 syntax conventions. Parameters are created and stored in the Params property.

For example:

PSQLQuery1->ParamCheck = true; // true by default
PSQLQuery1->SQL->Text = "select * from events where location = :Location";
PSQLQuery1->Params->Items[0]->AsInteger =  parameter_value;
// alternatively:
// PSQLQuery1->ParamByName("Location")->AsInteger = parameter_value;
PSQLQuery1->Open();
...

Have a look at the TPSQLQuery.Params documentation for more details.