-- Oracle 12c: SQL Functions

-- This function is useful in validation the datatype 

SELECT
  VALIDATE_CONVERSION(1000 AS BINARY_DOUBLE) is_binary_double,
  VALIDATE_CONVERSION(NULL AS BINARY_DOUBLE) is_binary_double
FROM DUAL;

-- This function APPROX_COUNT_DISTINCT is useful to compute approximate
-- counts in large tables

SELECT
 APPROX_COUNT_DISTINCT(customer_id) approx_customer_cnt,
 COUNT(DISTINCT customer_id) dist_customer_cnt
FROM edw_fact_sales
;