Delete specific records on MSSQL

Question

I'm trying to delete specific records from a table using where clause but unable to do so. The command executes successfully but says zeros rows are modified.enter image description here

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I'm still in the starting stage of learning SQL. Thanks for helping out

Be careful, it will delete not a specific record but all records matching the `IS NULL` condition. — eckes, Aug 12 '17 at 16:51
OMG! that simple can you tell me whats the difference between 'is' and '=' in that statement. — kaushik reddy, Aug 12 '17 at 16:51
A good explanation of IS NULL, IS NOT NULL versus comparison operators is discussed here: https://stackoverflow.com/questions/9581745/sql-is-null-and-null — drew kroft, Aug 12 '17 at 16:55

score 1 · Accepted Answer · answered Aug 12 '17 at 16:50

1

= NULL never returns true -- almost all comparisons with NULL return NULL, which is treated as false. The correct logic is IS NULL:

delete from Patient
    where PatientCountry is null

answered Aug 12 '17 at 16:50

Gordon Linoff

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score 1 · Answer 2 · answered Aug 12 '17 at 16:51

1

If you want find or delete null values then dont use "=" but "is". It should be:

delete from patient where patientcountry is null;

answered Aug 12 '17 at 16:51

Grzegorz Grabek

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Delete specific records on MSSQL

2 Answers2