SQL query to update table columns where input parameters are not null?
I have a table that has the following columns.
Ticket_id (Primary key, Int)
Attachment1 (varchar)
Attachment2 (varchar)
Attachment3 (varchar)
Attachment4 (varchar)
Attachment5 (varchar)
I am writing a stored proc to update this table. there are 6 inputs for the above columns.
@Attached_File1 VARCHAR(MAX), @Attached_File2 VARCHAR(MAX), @Attached_File3 VARCHAR(MAX), @Attached_File4 VARCHAR(MAX), @Attached_File5 VARCHAR(MAX), @Ticket_ID BIGINT
I want to write a sql query that will update the table with the values given in the input parameters. BUT I shouldn't be overriding nullable attachment columns. I mean, I only need to use parameters that contain data.
For example, if the ha table contains the string [10, "aaa", "bbb", null, null, null] and the input parameters are (10, null, null, "ccc", "ddd", null), then after the update the line becomes [10, "aaa", "bbb", "ccc", "ddd", null]
How do I check for null / empty strings and generate an update request for that?
You can use ISNULL
UPDATE table_name SET
Attachment1 = ISNULL(Attachment1, @Attached_File1),
Attachment2 = ISNULL(Attachment2, @Attached_File2),
Attachment3 = ISNULL(Attachment3, @Attached_File3),
Attachment4 = ISNULL(Attachment4, @Attached_File4),
Attachment5 = ISNULL(Attachment5, @Attached_File5)
WHERE Ticket_id = @Ticket_ID
This solution does not overwrite the existing value with the new one. If you want to do this, you have to switch the values around:
ISNULL(@Attached_File1, Attachment1)
You can try this:
update MY_TABLE set Attached_File1 = ISNULL(@parameter1, Attached_File1);
You can simply:
SET
AttachmentX = ISNULL(AttachmentX, @Attached_FileX)
or if the parameters can be empty strings
AttachmentX = ISNULL(AttachmentX, NULLIF(@Attached_FileX, ''))
In your expression, UPDATE
you can use an operator COALESCE
, for example:
SET Attachment1 = COALESCE(@Attached_File1, Attachment1)
If @Attached_File1
- NULL
, then the current value Attachment1
will actually remain unchanged.