MYSQL syntax not evaluating not equal to in presence of NULL

I am having trouble with a mysql query. I want to exclude values of 2. So I thought I would do following:

table products


id | name     | backorder
-------------------
1  | product1 | NULL
2  | product2 | NULL
3  | product3 | 2


SELECT name from `products` p
WHERE backorder <> '2'

但是，这并没有给出Product1，Product2的预期结果，而是给出了一个空的结果表。

On the other hand if I use 

SELECT name from `products` p
WHERE backorder = '2'

Then it produces: product3. But I want to get those records where it is not equal to 2.

Something is not working with the <> '2'. Could it be that the NULL values are throwing it off? Can anyone suggest a fix.

Thanks in advance!

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最佳答案

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
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Try this and see.

SELECT name from `products` p
WHERE backorder != '2'
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Sorry to open this

We can use this also

SELECT name
from   products p
WHERE  COALESCE(backorder,1)  <> 2
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Use the <=> operator.

You can use:

SELECT `name` FROM `products` `p`
WHERE NOT `backorder` <=> '2'

or

SELECT `name` FROM `products` `p`
WHERE !(`backorder` <=> '2')

See this answer for more information about the <=> operator:

What is this operator <=> in MySQL?


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