add date format and orDefault helpers

backend/internal/data/repo/query_helpers.go

@@ -0,0 +1,18 @@
+package repo
+
+import "time"
+
+func sqliteDateFormat(t time.Time) string {
+	return t.Format("2006-01-02 15:04:05")
+}
+
+// orDefault returns the value of the pointer if it is not nil, otherwise it returns the default value
+//
+// This is used for nullable or potentially nullable fields (or aggregates) in the database when running
+// queries. If the field is null, the pointer will be nil, so we return the default value instead.
+func orDefault[T any](v *T, def T) T {
+	if v == nil {
+		return def
+	}
+	return *v
+}