SELECT a.account_no, (CASE WHEN e.reading_month IS NULL then “” WHEN e.reading_month IS NOT NULL then STR_TO_DATE(CONCAT(e.reading_month,” “,e.reading_year), “%m %Y”) end) as reading_date, (CASE WHEN e.reading_month IS NULL then “” else e.reading end) as reading FROM swws_users as a, water_reading as e WHERE e.account_no = a.account_no OR e.account_no is NULL AND (CASE WHEN e.reading_month IS NULLRead more