How to check if a column is empty in SQL

Question

I have an order table with the user_fk column and invoice column. Let's just say I want to get an order instance that is related to my user but with an empty invoice column. How do I do that with mysql?

perhaps this will illustrate it

"SELECT * FROM order WHERE user_fk = $user_fk AND invoice === false;"

edit: invoice column is an interger

Unclear, What do you mean `with an empty` on invoice column? — D-Shih, Apr 15 '22 at 14:29

score 1 · Accepted Answer · answered Apr 15 '22 at 14:28

1

SELECT * FROM order WHERE user_fk = $user_fk AND invoice is null or invoice = '';

Try this if invoice supports null

answered Apr 15 '22 at 14:28

Mykyta Halchenko

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score 0 · Answer 2 · answered Apr 15 '22 at 14:33

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You can check whether the invoice column is null or length of column is 0.

SELECT * FROM order WHERE user_fk = $user_fk AND (invoice is null or len(invoice)=0);

answered Apr 15 '22 at 14:33

Kazi Mohammad Ali Nur Romel

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How to check if a column is empty in SQL

2 Answers2