I am working in a company where we use Spring -Hibernate and mysql database at backend.
There is a table tc_wallet
In this table i have an column tips_type which has values
''
(empty) NULL
--> No value has been initialized Now when i fire a query:
SELECT *
FROM `tc_wallet`
WHERE
login_id = 'gaurav.wakharkar'
AND `delete_flag` = 'F'
AND `tips_type` != 'Collection'
I get results which has column value as '' (empty).
Login_id tips_type
gaurav.wakharkar
gaurav.wakharkar
gaurav.wakharkar
But even (NULL) is != 'Collection' should satisfy the above condition.
So according to me the result should have been .
Login_id tips_type
gaurav.wakharkar
gaurav.wakharkar
gaurav.wakharkar
gaurav.wakharkar (NULL)
gaurav.wakharkar (NULL)
Is there some issue while checking/comparing values with (NULL) ?
Does it behave differently ?
To check for nullness, you want to use IS NULL
. Comparing NULL
to something else with the equality operator (or the inequality operator) is always false.
Consider:
SELECT *
FROM `tc_wallet`
WHERE
login_id = 'gaurav.wakharkar'
AND `delete_flag` = 'F'
AND (`tips_type` IS NULL OR `tips_type` != 'Collection')
change your query to
SELECT
*
FROM
`tc_wallet`
WHERE login_id = 'gaurav.wakharkar'
AND `delete_flag` = 'F'
AND (`tips_type` != 'Collection' or `tips_type` is null)
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