feat: add id null json values til

postgres/identify-null-json-values.md

@@ -0,0 +1,9 @@
+# Idenfity `NULL` JSON Values
+
+```sql
+SELECT id, metadata FROM $TABLE_NAME
+WHERE jsonb_typeof(metadata) != 'object'
+OR jsonb_path_exists(metadata, '$.keyvalue() ? (@.value == null)')
+```
+
+Given a table, `$TABLE_NAME`, that possesses a JSONB column, `metadata`, the above query will return all rows in `$TABLE_NAME` where `metadata` is not `NULL`, but some value _within_ `metadata` is `NULL`.