diff --git a/src/db/ndns-db-tables.sql b/src/db/ndns-db-tables.sql
new file mode 100644
index 0000000..8ecc3b0
--- /dev/null
+++ b/src/db/ndns-db-tables.sql
@@ -0,0 +1,39 @@
+/*
+some difference with Alex's sql file:
+1. class field in table rrsets could be NULL
+2. type field in table rrsets is changed to text from integer(10)
+*/
+DROP TRIGGER IF EXISTS rrs_update;
+DROP TABLE IF EXISTS zones;
+DROP TABLE IF EXISTS rrsets;
+DROP TABLE IF EXISTS rrs;
+CREATE TABLE zones (
+  id    INTEGER NOT NULL PRIMARY KEY, 
+  name blob NOT NULL UNIQUE);
+CREATE TABLE rrsets (
+  id       INTEGER NOT NULL PRIMARY KEY, 
+  zone_id integer(10) NOT NULL, 
+  label   text NOT NULL, 
+  class   integer(10), 
+  type    text NOT NULL, 
+  ndndata blob, 
+  FOREIGN KEY(zone_id) REFERENCES zones(id) ON UPDATE Cascade ON DELETE Cascade);
+CREATE TABLE rrs (
+  id        INTEGER NOT NULL PRIMARY KEY, 
+  rrset_id integer(10) NOT NULL, 
+  ttl      integer(10) NOT NULL, 
+  rrdata   blob NOT NULL, 
+  FOREIGN KEY(rrset_id) REFERENCES rrsets(id) ON UPDATE Cascade ON DELETE Cascade);
+CREATE UNIQUE INDEX rrsets_zone_id_label_class_type 
+  ON rrsets (zone_id, label, class, type);
+CREATE INDEX rrs_rrset_id 
+  ON rrs (rrset_id);
+CREATE INDEX rrs_rrset_id_rrdata 
+  ON rrs (rrset_id, rrdata);
+CREATE TRIGGER rrs_update
+BEFORE INSERT ON rrs
+FOR EACH ROW
+BEGIN
+    DELETE FROM rrs WHERE rrset_id = NEW.rrset_id AND rrdata = NEW.rrdata;
+END;
+