If row is null else

Question

So I have a column named "votes" which have the value "NULL" when the row first gets created. At the end of the day, I will add the votes coming from another table and put all the votes into the correct row. The problem is that if it is the first time the row gets votes, I will have to write SET votes = '$votes' but if it already has votes I will have to write SET votes = votes + '$votes'. Is there any easy way to detect if it is null or if it has an value?

Do you want to add new votes to previous one ? So it increase each time — Mahmood Rehman
– Mahmood Rehman, Commented Jan 6, 2014 at 4:30
votes + '$votes' would try to add a string to a number. Just use votes + $votes — hjpotter92
– hjpotter92, Commented Jan 6, 2014 at 4:30

David Lin · Accepted Answer · 2014-01-06 04:31:20Z

3

You can use the ifnull MYSQL function, the SQL will be like

UPDATE .... SET votes = IFNULL(votes, 0) + votes

answered Jan 6, 2014 at 4:31

David Lin

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Padmanathan J · Accepted Answer · 2014-01-06 04:35:49Z

2

Use Ifnull

SET votes = IFNULL(votes, 0) + votes

answered Jan 6, 2014 at 4:35

Padmanathan J

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John Woo · Accepted Answer · 2014-01-06 04:29:23Z

2

try this, COALESCE or IFNULL.

SET votes = COALESCE(votes, 0) + '$votes'

if the value of votes is null, it will be converted to 0 other wise retain the original value and added it to your $votes.

answered Jan 6, 2014 at 4:29

John Woo

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Lightness Races in Orbit · Accepted Answer · 2014-01-06 04:38:55Z

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Initialise the field to 0 instead of NULL.

It makes sense for something to start off with no votes.

In fact, I'd make this column NOT NULL!

answered Jan 6, 2014 at 4:38

Lightness Races in Orbit

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