Updated migration script.

Author: mikecao

scripts/data-migrations/convert-utm-clid-columns.sql

@@ -45,4 +45,4 @@ SET fbclid = LEFT(SUBSTRING_INDEX(SUBSTRING_INDEX(REGEXP_SUBSTR(url_query, '(?:[
     utm_medium = LEFT(SUBSTRING_INDEX(SUBSTRING_INDEX(REGEXP_SUBSTR(url_query, '(?:[&?]|^)utm_medium=[^&]+'), '=', -1), '&', 1), 255),
     utm_source = LEFT(SUBSTRING_INDEX(SUBSTRING_INDEX(REGEXP_SUBSTR(url_query, '(?:[&?]|^)utm_source=[^&]+'), '=', -1), '&', 1), 255),
     utm_term = LEFT(SUBSTRING_INDEX(SUBSTRING_INDEX(REGEXP_SUBSTR(url_query, '(?:[&?]|^)utm_term=[^&]+'), '=', -1), '&', 1), 255)
-WHERE 1 = 1;
+WHERE url_query IS NOT NULL;