Add postgresql support

src/database/count_query.hpp

@@ -2,6 +2,7 @@
 
 #include <database/query.hpp>
 #include <database/table.hpp>
+#include <database/statement.hpp>
 
 #include <string>
 
@@ -15,20 +16,17 @@ struct CountQuery: public Query
       this->body += std::move(name);
     }
 
-    int64_t execute(sqlite3* db)
+    int64_t execute(DatabaseEngine& db)
     {
-      auto statement = this->prepare(db);
+      auto statement = db.prepare(this->body);
       int64_t res = 0;
-      if (sqlite3_step(statement.get()) == SQLITE_ROW)
-        res = sqlite3_column_int64(statement.get(), 0);
+      if (statement->step() != StepResult::Error)
+        res = statement->get_column_int64(0);
       else
         {
           log_error("Count request didn’t return a result");
           return 0;
         }
-      if (sqlite3_step(statement.get()) != SQLITE_DONE)
-        log_warning("Count request returned more than one result.");
-
       return res;
     }
 };