SQL WHERE condition is not equal to

Question

Is it possible to negate a where clause   e g   DELETE   FROM table WHERE id    2

User · Answer

Use  lt  gt  to negate the where clause

User · Answer

delete from table where id  lt  gt  2    edit  to correct syntax for MySQL

User · Answer

WHERE id  lt  gt  2 should work fine   Is that what you are after

User · Answer

Your question was already answered by the other posters  I d just like to point out that    delete from table where id  lt  gt  2    or variants thereof  not id   2 etc  will not delete rows where id is NULL   If you also want to delete rows with id   NULL   delete from table where id  lt  gt  2 or id is NULL

User · Answer

Look back to formal logic and algebra  An expression like  A  amp  B  amp   D   E    may be negated in a couple of ways    The obvious way      A  amp  B  amp    D   E      The above can also be restated  you just need to remember some properties of logical expressions       A  amp  B   is the equivalent of   A    B      A   B   is the equivalent of   A  amp   B       A   is the equivalent of  A     Distribute the NOT     across the entire expression to which it applies  inverting   operators and eliminating double negatives as you go along        A    B      D  amp   E      So  in general  any where clause may be negated according to the above rules  The negation of this  select   from foo where      test-1   and      test-2   and      test-3         OR test-4           is  select   from foo where NOT           test-1            and      test-2            and      test-3                  OR test-4                               or  select   from foo where        not test-1   OR         not test-2   OR         not test-3          and not test-4            Which is better  That s a very context-sensitive question  Only you can decide that   Be aware  though  that the use of NOT can affect what the optimizer can or can t do  You might get a less than optimal query plan

User · Answer

I was just solving this problem  If you use  lt   or is not in on a variable  that is null  it will result in false  So instead of  lt   1  you must check it like this    AND  isdelete is NULL or isdelete   0

User · Answer

Best solution is to use   DELETE FROM table WHERE id NOT IN   2

User · Answer

You can do like this  DELETE FROM table WHERE id NOT IN   2     OR   DELETE FROM table WHERE id  lt  gt   2    As  Frank Schmitt noted  you might want to be careful about the NULL values too  If you want to delete everything which is not 2 including the NULLs  then add OR id IS NULL to the WHERE clause

User · Answer

You could do the following   DELETE   FROM table WHERE NOT id   2

User · Answer

Yes  If memory serves me  that should work  Our you could use   DELETE FROM table WHERE id  lt  gt  2

[mysql] SQL WHERE condition is not equal to?

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