Update Where Null in Sql Server

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I am trying to update image column with A string where Its Is NULL Now..But
Its not working...My Query Below..
Any One Can Explain me why Its Happens..

update Info set image='Image/defalt.png' where Image=null

Posted 26-May-14 6:14am

Mahesh@Dev

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[no name] 26-May-14 12:17pm

What is it that you think "Its not working" means?

2 solutions

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DamithSL · Accepted Answer · 2014-05-26T06:24:00

Solution 1

try below

SQL

UPDATE
      Info 
SET
    image='Image/defalt.png' 
WHERE
   Image IS NULL

Quote:
How can we test for NULL values?

It is not possible to test for NULL values with comparison operators, such as =, <, or <>.

We will have to use the IS NULL and IS NOT NULL operators instead.

Reference[^]

Posted 26-May-14 6:24am

DamithSL

Updated 26-May-14 6:28am

v2

Comments

Ziee-M 26-May-14 12:35pm

my 5, i never thought about it, now its saved deeep in my brain! (talking about the info in the bottom)

Maciej Los 26-May-14 15:06pm

+5Have a look at my answer ;)

Maciej Los · Accepted Answer · 2014-05-26T09:06:00

Solution 2

Strictly saying: it's impossible to use comparison operators, like: <, > or =.
Have a look here: NULL Comparison Search Conditions[^]

To use comparison operators with NULL, use COALESCE[^] function, which evaluates NULL values with other.
Sample 1

SQL

SELECT IntField
FROM TableName
WHERE COALESCE(IntField, 0) = 0

Sample 2

SQL

SELECT StringField
FROM TableName
WHERE COALESCE(StringField, '') = ''

Posted 26-May-14 9:06am

Maciej Los

Comments

Kornfeld Eliyahu Peter 26-May-14 15:23pm

It is important to know that there is a SQL function - ISNULL that has the same format and purpose that of COALESCE.
The main difference that the first parameter can be evaluated twice in COALESCE (in case when the parameter not a single column but a sub-query), once for the check and once for the return if the first attempt yields no-null value. This behavior can lead to some surprises, as the two runs can yield different values...
The meaning of all this that ISNULL is safer for most purposes (and has better performance too)...