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A new SQL function in ORACLE 12.2 is validate_conversion which enables us to check whether a conversion is possible or not receiving a “boolean” (0/1) value as result.

 

Example checking conversion of a string value into a date

In case of a string to date conversion error we would like to return the 1st of January of 2016.

WITH data (str) AS (SELECT '10.15.2015' FROM dual union all
                    SELECT '15.10.2015' FROM dual union all
                    SELECT '30.02.2015' FROM dual
                   )
SELECT str
     , VALIDATE_CONVERSION(str as date,'DD.MM.YYYY') conversion_possible
 FROM data
/

STR        CONVERSION_POSSIBLE
---------- -------------------
10.15.2015                   0
15.10.2015                   1
30.02.2015                   0

When checking conversion of a string into a date it is also possible to specifcy the language of the date string.

WITH data (str) AS (SELECT '15. March 2015' FROM dual union all
                    SELECT '15. März 2015' FROM dual union all
                    SELECT '15. Mars 2015' FROM dual
                   )
SELECT str
     , VALIDATE_CONVERSION(str as date,'DD. Month YYYY','NLS_DATE_LANGUAGE=GERMAN') conversion_possible
  FROM data
/

STR            CONVERSION_POSSIBLE
-------------- -------------------
15. March 2015                   0
15. März 2015                    1
15. Mars 2015                    0

Conclusion

Another great little helper especially when  loading data from 3rd parties. How often have we struggled just because a single value in a single record just did not fit the specifications. Using validate_conversion we can easily find those values, exclude them, log them and so on.