Issue
I need to get only NULL
values in checktime or pin columns
My SQL query
SELECT emp.`emp_id`,cio.`pin`,cio.`checktime` FROM payroll.employees AS emp
LEFT JOIN (SELECT * FROM zkteco_biotime.checkinout WHERE checktime > "2022-09-20 23:59:59") AS cio ON emp.emp_id = cio.pin
WHERE emp.status=0 GROUP BY emp_id ORDER BY checktime DESC
when i use AND cio.checktime=NULL
after emp.status=0
it showing me result blank
Solution
You should use
AND cio.checktime IS NULL
Null compared with anything will result in FALSE. Only "IS NULL" and "IS NOT NULL" may return TRUE.
Answered By - arheops Answer Checked By - Robin (PHPFixing Admin)
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