diff --git a/sql/create.sql b/sql/create.sql
index a94feb3..17cdeab 100644
--- a/sql/create.sql
+++ b/sql/create.sql
@@ -1,11 +1,13 @@
 
+PRAGMA foreign_keys = ON;
+
 CREATE TABLE country (
-    alpha2 TEXT    NOT NULL CHECK(LENGTH(alpha2) = 2),
-    alpha3 TEXT    NOT NULL CHECK(LENGTH(alpha3) = 3),
-    num    INTEGER NOT NULL CHECK(num >= 0),
+    alpha2 TEXT    NOT NULL CHECK (alpha2 REGEXP '[A-Z]{2}'),
+    alpha3 TEXT    NOT NULL CHECK (alpha3 REGEXP '[A-Z]{3}'),
+    num    INTEGER NOT NULL CHECK (num >= 0),
     name   TEXT    NOT NULL,
 
-    is_visible INTEGER NOT NULL CHECK(is_visible = TRUE OR is_visible = FALSE) DEFAULT TRUE,
+    is_visible INTEGER NOT NULL CHECK (is_visible = TRUE OR is_visible = FALSE) DEFAULT TRUE,
 
     CONSTRAINT pk_country PRIMARY KEY (alpha2),
     CONSTRAINT sk_country_alpha3 UNIQUE (alpha3),
@@ -14,7 +16,7 @@ CREATE TABLE country (
 ) STRICT;
 
 CREATE TABLE currency (
-    code     TEXT NOT NULL CHECK(LENGTH(code) = 3),
+    code     TEXT NOT NULL CHECK (code REGEXP '[A-Z]{3}'),
     name     TEXT NOT NULL,
     symbol   TEXT,
 
@@ -24,8 +26,8 @@ CREATE TABLE currency (
 ) STRICT;
 
 CREATE TABLE wine_variety (
-    code    TEXT NOT NULL CHECK(LENGTH(code) = 2),
-    type    TEXT NOT NULL CHECK(type IN ('R', 'W')),
+    code    TEXT NOT NULL CHECK (code REGEXP '[A-Z]{2}'),
+    type    TEXT NOT NULL CHECK (type IN ('R', 'W')),
     name    TEXT NOT NULL,
     comment TEXT,
 
@@ -33,7 +35,7 @@ CREATE TABLE wine_variety (
 ) STRICT;
 
 CREATE TABLE AT_bundesland (
-    id     INTEGER NOT NULL CHECK(id >= 0),
+    id     INTEGER NOT NULL CHECK (id >= 0),
     short1 TEXT    NOT NULL,
     short2 TEXT,
     name   TEXT    NOT NULL,
@@ -44,32 +46,43 @@ CREATE TABLE AT_bundesland (
     CONSTRAINT sk_AT_bundesland_name UNIQUE (name)
 ) STRICT;
 
-CREATE TABLE AT_gemeinde (
-    gkz     INTEGER NOT NULL CHECK(gkz >= 10000 AND gkz <= 99999),
-    land_id INTEGER NOT NULL CHECK(land_id = gkz / 10000),
+CREATE TABLE AT_gem (
+    gkz     INTEGER NOT NULL CHECK (gkz >= 10000 AND gkz <= 99999),
+    land_id INTEGER NOT NULL GENERATED ALWAYS AS (gkz / 10000) VIRTUAL,
     name    TEXT    NOT NULL,
 
-    CONSTRAINT pk_AT_gemeinde PRIMARY KEY (gkz),
-    CONSTRAINT fk_AT_gemeinde_AT_bundesland FOREIGN KEY (land_id) REFERENCES AT_bundesland (id)
+    CONSTRAINT pk_AT_gem PRIMARY KEY (gkz),
+    CONSTRAINT fk_AT_gem_AT_bundesland FOREIGN KEY (land_id) REFERENCES AT_bundesland (id)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT
+) STRICT;
+
+CREATE TABLE AT_kg (
+    kgnr INTEGER NOT NULL CHECK (kgnr > 0 AND kgnr < 100000),
+    gkz  INTEGER NOT NULL,
+    name TEXT    NOT NULL,
+
+    CONSTRAINT pk_AT_kg PRIMARY KEY (kgnr),
+    CONSTRAINT fk_AT_kg_AT_gem FOREIGN KEY (gkz) REFERENCES AT_gem (gkz)
         ON UPDATE CASCADE
         ON DELETE RESTRICT
 ) STRICT;
 
 CREATE TABLE AT_ort (
-    okz  INTEGER NOT NULL CHECK(okz > 0),
-    gkz  INTEGER NOT NULL,
+    okz  INTEGER NOT NULL CHECK (okz > 0 AND okz < 100000),
+    kgnr INTEGER NOT NULL,
     name TEXT    NOT NULL,
 
     CONSTRAINT pk_AT_ort PRIMARY KEY (okz),
-    CONSTRAINT fk_AT_ort_AT_gemeinde FOREIGN KEY (gkz) REFERENCES AT_gemeinde (gkz)
+    CONSTRAINT fk_AT_ort_AT_kg FOREIGN KEY (kgnr) REFERENCES AT_kg (kgnr)
         ON UPDATE CASCADE
         ON DELETE RESTRICT
 ) STRICT;
 
 CREATE TABLE AT_plz (
-    plz  INTEGER NOT NULL CHECK(plz >= 1000 AND plz <= 9999),
+    plz  INTEGER NOT NULL CHECK (plz >= 1000 AND plz <= 9999),
     okz  INTEGER NOT NULL,
-    id   INTEGER NOT NULL CHECK(id = plz * 100000 + okz),
+    id   INTEGER NOT NULL GENERATED ALWAYS AS (plz * 100000 + okz) STORED,
     name TEXT    NOT NULL,
 
     CONSTRAINT pk_AT_plz PRIMARY KEY (plz, okz),
@@ -80,7 +93,7 @@ CREATE TABLE AT_plz (
 ) STRICT;
 
 CREATE TABLE origin (
-    code        TEXT NOT NULL CHECK(LENGTH(code) = 4),
+    code        TEXT NOT NULL CHECK (code REGEXP '[A-Z]{4}'),
     parent_code TEXT,
     name        TEXT NOT NULL,