带有条件的MySQL子查询，结果不同

Question

I'm having a problem with a project I'm working on.

I have 2 tables. First table is workorder . This table consists of the following columns:

• id
• relation_code
• generated
• exportready

Second table is workorder_records . Columns:

• id
• workorder_id
• description
• approved

I need to select every workorder where generated = 0 and exportready = 0 and its records count. But, only records where approved = 0 and description != ''.

I've written this query for it:

SELECT *, (SELECT COUNT(*) FROM workorder_records
WHERE workorder_records.approved = 0
AND workorder_records.workorder_id = workorder.id
AND workorder_records.description != ''
) as totalunapproved
FROM workorder
WHERE workorder.generated = 0
AND workorder.exportready = 0

I get the correct result when I execute this in phpMyAdmin. When I run this through a PHP script connected to the same database, I get different results. For example, a result where workorder_records.description was actually empty but still returned by the query function.

SQL Fiddle Link: http://sqlfiddle.com/#!2/ea8aa/3

Any help is appreciated.

Edit: I solved the problem by doing the checks in PHP. This is of course not ideal but I just can't figure out why the conditional subquery works in PHPMyAdmin and not in my PHP script.

Answer 1

Try to replace this

workorder_records.description != ''

to

workorder_records.description IS NOT NULL

And make workorder_records.description by default as null.