Posted by John Taylor-Johnston on 08/22/05 07:04

varchar:
colname<>''
Thanks,
John

Jasper Bryant-Greene wrote:

> John Taylor-Johnston wrote:
>
>> In php, if I wanted to know if $mydata->email contained something, I
>> would do this, right?
>> if ($mydata->email)
>> {}
>>
>> How would I express this in SQL (MySQL)?
>
>
> That doesn't tell you if $mydata->email contains something. It tells
> you whether the value of $mydata->email, when cast to boolean, equals
> TRUE. If $mydata->email equaled zero or the string "0", it would still
> contain something, but that if statement would not get executed.
>
> In MySQL, it would depend on the datatype. You could do any of the
> following, depending on what you actually want to do:
>
> colname<>''
> colname<>0
> colname IS NOT NULL
>
> Or, if you're in MySQL >= 5.0.2 and are using true boolean values:
>
> colname IS TRUE
>
> or, if you just want to check if it's TRUE or UNKNOWN:
>
> colname IS NOT FALSE
>
>
> Jasper

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