Not Equal ≪≫ != Operator on Null

Not equal != operator on NULL

<> is Standard SQL-92; != is its equivalent. Both evaluate for values, which NULL is not -- NULL is a placeholder to say there is the absence of a value.

Which is why you can only use IS NULL/IS NOT NULL as predicates for such situations.

This behavior is not specific to SQL Server. All standards-compliant SQL dialects work the same way.

Note: To compare if your value is not null, you use IS NOT NULL, while to compare with not null value, you use <> 'YOUR_VALUE'. I can't say if my value equals or not equals to NULL, but I can say if my value is NULL or NOT NULL. I can compare if my value is something other than NULL.

Not equal query excludes NULL values

Nulls are not counted in comparison, if you want null values to be returned then you need to execute the following query:

SELECT * FROM MasterList WHERE Requested <> "Yes" OR Requested IS NULL;

How can I exclude NULL of not equal operator?

This you can use for MySQL,

...WHERE IFNULL(col,0) <> 10

If the value of col is NULL then IFNULL(col,0) will convert the value to '0' and perform the comparison. So you will get all the records except only 10.

SQL not equals & null

In Oracle, there is no difference between an empty string and NULL.

That is blatant disregard for the SQL standard, but there you go ...

In addition to that, you cannot compare against NULL (or not NULL) with the "normal" operators: "col1 = null" will not work, "col1 = '' " will not work, "col1 != null" will not work, you have to use "is null".

So, no, you cannot make this work any other way then "col 1 is null" or some variation on that (such as using nvl).

MySQL - NULL safe NOT equal operator

COALESCE(tab.id, 0) != 1

Can be used here if you like it. I goes through the parameters, and returns the first value that isn't NULL. In this case if it's NULL, it will compare 0 != 1. Although it may use more signs, it's still easier to manage instead of being forced to always have opposite "booleans" as a solution in those cases.

Read documentation for COALESCE()

MYSQL syntax not evaluating not equal to in presence of NULL

use IS NULL or IS NOT NULL to compare NULL values because they are simply unknown.

SELECT name 
from   products p
WHERE  backorder IS NULL OR backorder <> 2

SQLFiddle Demo
SQLFiddle Demo (added some records)
Working with NULL Values

SQL Where not equal does not return NULL results

As per your where clause it compares null != 'Iron', which evaluates to UNKNOWN which neither true nor false based on SQL's 3 way logic. Hence it is not returned by the query.

If you need the null row to be resulted, you should use

where content !='Iron' or content is null

Edit: One more option is to use the relational null-safe equality operator <=> with a negation.

not content <=> 'Iron'

From the documentation,

NULL-safe equal. This operator performs an equality comparison like the = operator, but returns 1 rather than NULL if both operands are NULL, and 0 rather than NULL if one operand is NULL.
The <=> operator is equivalent to the standard SQL IS NOT DISTINCT FROM operator.

mysql> 
   SELECT 1 <=> 1, NULL <=> NULL, 1 <=> NULL
   UNION
   SELECT 1 = 1, NULL = NULL, 1 = NULL;

Returns

  1 vs 1  |  NULL vs NULL  | 1 vs NULL |  Comment
  --------------------------------------------------
     1    |        1       |    0      |  for <=>
     1    |       NULL     |   NULL    |  for  =

DB2 Select where not equal to string that is NULL

If you really want NULLs, then why not

SELECT COLUMN1 FROM MYTABLE WHERE (COLUMN1 != 'A' OR COLUMN1 IS NULL)

???

How does not equal in snowflake exactly work?

I think you should use EQUAL_NULL here. EQUAL_NULL Compares whether two expressions are equal. The function is NULL-safe, meaning it treats NULLs as known values for comparing equality. Note that this is different from the EQUAL comparison operator (=), which treats NULLs as unknown values.

https://docs.snowflake.com/en/sql-reference/functions/equal_null.html#equal-null

CREATE TABLE NULL_TEST(PRODUCT VARCHAR, STATUS VARCHAR);

INSERT INTO NULL_TEST VALUES('1111','DELETED');
INSERT INTO NULL_TEST VALUES('1112',NULL);


select * from NULL_TEST where NOT EQUAL_NULL(status,'DELETED');

Not Equal ≪≫ != Operator on Null