Refactor and remove sqlite and replace with MySQL

internal/helpers/intptr.go

@@ -0,0 +1,13 @@
+package helpers
+
+import (
+	"database/sql"
+)
+
+func IntPtrIfValid(val sql.NullInt64) *int {
+	if val.Valid {
+		n := int(val.Int64)
+		return &n
+	}
+	return nil
+}