Need help with the date syntax

[eldan88]

Hey Guys. My previous developer wrote the following date syntax and I am trying to understand what it means, as I never seen a syntax like that.

 

Particular this ....

AND MONTH(`checkout_date`) = MONTH(CURRENT_DATE - INTERVAL $month_skip_number MONTH) 
AND YEAR(  `checkout_date` ) = YEAR( CURRENT_DATE )

Is he assigning the files value to the current month and year??

 

Below is the full syntax

$checkout = "SELECT DAY(`checkout_date`) AS days, count(`checkout_date`) AS total_checkouts, sum(cart_total) AS total  
FROM  `checkout` 
WHERE `store_id`= $store_id 
AND MONTH(`checkout_date`) = MONTH(CURRENT_DATE - INTERVAL $month_skip_number MONTH) 
AND YEAR(  `checkout_date` ) = YEAR( CURRENT_DATE ) 
GROUP BY days";

[kicken]

He's checking a couple of conditions, not assigning anything.

MONTH(`checkout_date`) = MONTH(CURRENT_DATE - INTERVAL $month_skip_number MONTH)

That checks if the MONTH portion of the date stored in checkout_date is equal to the MONTH portion of the current date less $month_skip_number months.

 

YEAR(  `checkout_date` ) = YEAR( CURRENT_DATE )

This checks if the YEAR portion of the date stored in checkout_date matches the current year.

[mac_gyver]

also, the date math isn't doing what you expect. by only modifying the month, trying to go back past the start of the year, will try to find dates in the future. use this -

EXTRACT(YEAR_MONTH FROM checkout_date) = EXTRACT(YEAR_MONTH FROM CURRENT_DATE - INTERVAL $month_skip_number MONTH)

[eldan88]

Thanks for the clarification Kicken.

 

mac_gyver. Thank you for pointing that out.... what is the "INTERVAL" supposed to stand for?

[mac_gyver]

all your basic mysql questions are answered here - http://dev.mysql.com/doc/refman/5.6/en/index.html

[eldan88]

Okay Will do. Thanks!