left joined table all nulls?

[webguy262]

I'm trying to do a simple left join of two table on a common column.

 

For some reason, the joined table values are all coming back NULL.

 

What am I missing?

 

SELECT *

FROM surveyview_staging

LEFT JOIN surveyallanswers_staging ON 'surveyallanswers_staging.response_id' = 'surveyview_staging.response_id'

[chrisshennan]

Hi,

 

It wouldn't be because you've got apostrophes around the fields in the ON part of the query would it?

 

Try the following and let me know how you get on.

 

SELECT *

FROM surveyview_staging

LEFT JOIN surveyallanswers_staging ON surveyallanswers_staging.response_id = surveyview_staging.response_id

[webguy262]

I swear, I'll never grasp the use of  ', `," in php & phpmyadmin (in particular)!

 

I need to do some googling!

 

Thanks!

[Maq]

Single quotes are for strings.  Backtics are for table names that are the same as reserved words, which you should avoid.  Although, they won't hurt even if they're not needed.

[chrisshennan]

The basic rules I use with ', ` and " are:-

 

I only use ` in MySQL and only where the field is a reserved word i.e. you have a field called date so the query ends up like

 

SELECT title, `date` FROM sometable

 

I use ' and " within PHP for different things:

 

if we have a variable called $test with a value of "this is my sample data";

 

' spits out exactly what's within the apostrophes (variable aren't evaluated) so

 

echo 'My text is: $test'; will output

My text is: $test

 

" allows the variables to be evaluated so

 

echo "My text is: $test"; will output

My text is: this is my sample data

 

I hope this helps

[webguy262]

Chris / Maq

 

Thanks for the guidance! Very clear!

 

One question...  Is there a difference between $var['foobar'] and $var[foobar]?

 

I recall having to use one or the other but I'm not clear on the difference.

 

Hard to goog this kind of stuff b/c the punctuation gets ignored.

[chrisshennan]

Hi,

 

To use associative arrays you would use $var['foobar'] however $var[foobar] would result in a "use of undefined constant" unless you had specifically declared foobar as a constant.

 

Typically you have to use quotes or apostrophes around associative array keys

 

i.e. $var['foobar']

 

and numeric based keys don't have the quotes / apostrophe.

 

i.e. $var[0]

 

I hope this helps

[webguy262]

thanks!