🐛 Fix issue with SELECT count(*) for column-based database

When you do a SELECT count(*), SQLite does not request any column, resulting in an empty SELECT for the remote database, which isn't supported by most SQL query engines.
To work around this, we arbitrarily add the first column to the SELECT

Author: julien040

module/db_helper.go

@@ -144,6 +144,14 @@ func efficientConstructSQLQuery(
 		cols = append(cols, col.Realname)
 	}
 
+	// If no columns are used, we add the first one
+	//
+	// When SQLite does a SELECT count(*), it doesn't use any column, so we need to add at least one column
+	// because most SQL engines require at least one column in the SELECT clause.
+	if len(cols) == 0 {
+		cols = append(cols, columns[0].Realname)
+	}
+
 	query.Select(cols...).From(table)
 
 	// Add the constraints (where, limit, offset)