Merge pull request #349 from coderxio/jrlegrand/gtin

Create GTINs mart

dbt/sagerx/models/marts/ndc/gtins.sql

@@ -0,0 +1,97 @@
+-- gtins.sql
+
+with
+
+ndcs as (
+
+    select
+        ndc11,
+        replace(ndcpackagecode, '-', '') as ndc10,
+        ndcpackagecode as ndc,
+        concat(
+            '003',
+            replace(ndcpackagecode,'-', '')
+        ) as gtin13,
+        concat(
+            '3',
+            replace(ndcpackagecode,'-', '')
+        ) as gtin11,
+        concat(
+            '03',
+            split_part(ndcpackagecode, '-', 1)
+        ) as gs1_company_prefix
+
+    from {{ ref('stg_fda_ndc__ndcs') }}
+
+),
+
+digits as (
+
+    -- split the 13-digit number into individual digits
+    select 
+        ndc,
+        position,
+        substring(gtin13 from position for 1)::int as digit
+    from ndcs,
+        generate_series(1, 13) as position
+
+),
+
+products as (
+
+    -- apply the alternating multiplication rule
+    select 
+        *,
+        case
+            when position % 2 = 1
+                then digit * 3
+            else digit * 1 
+        end as product
+    from digits
+
+),
+
+sums as (
+
+    -- sum of the products of each digit
+    select
+        ndc,
+        sum(product) as sum
+    from products
+    group by ndc
+
+),
+
+check_digits as (
+
+    -- round the sum to the nearest 10 and subtract the sum
+    select
+        ndc,
+        ceil(sum / 10.0) * 10 - sum as check_digit
+    from sums
+
+),
+
+gtin14s as (
+
+    -- concatenate the gtin13 and check_digit
+    select
+        ndc11,
+        ndc10,
+        ndcs.ndc,
+        concat(
+            gtin13,
+            check_digit
+        ) as gtin14,
+        concat(
+            gtin11,
+            check_digit
+        ) as gtin12,
+        gs1_company_prefix
+    from ndcs
+    left join check_digits
+        on check_digits.ndc = ndcs.ndc
+
+)
+
+select * from gtin14s