Question

Following is my sql query kindly let me know why is it returning null

Select STR_TO_DATE ('11-APR-74','%e%b%Y')
OR
Select DATE_FORMAT ('11-APR-74','%e%b%Y')

Answer 1

From MySQL STR_TO_DATE function:

The server scans str attempting to match format to it. … Scanning
starts at the beginning of str and fails if format is found not to
match.

This is why your first query fails: 11-APR-74 does not look like %e%b%Y, so date cannot be parsed. You should do instead

SELECT STR_TO_DATE ('11-APR-74','%e-%b-%Y')

From MySQL Date and Time types:

Although MySQL tries to interpret values in several formats, date
parts must always be given in year-month-day order (for example,
’98-09-04′), rather than in the month-day-year or day-month-year
orders commonly used elsewhere (for example, ’09-04-98′, ’04-09-98′).

This is why your second query fails: 74 is not a valid day of month, you should do instead

SELECT DATE_FORMAT ('74-APR-11','%e%b%Y')

Note, that DATE_FORMAT is usually used on DB values, not string literals as you do – to get an output different from the default one.