Select a substring (date) and convert it - php

Question

I have a table with a column DateFrom (Varchar) that uses format YYYY-MM-DDTHH:MM:SS
to get the time for a specific date I use this sql:
SELECT SUBSTRING(DateFrom FROM 12 FOR 5) AS From FROM calendar WHERE SUBSTRING(DateFrom FROM 1 FOR 10) = "'.$date.'"
this gives me:
HH:MM
.$date
(from datepicker) has format DD.MM.YYYY
I'm creating a website that should let the user see times associated with a date
can I convert the string from my database before checking if it's equal to .$date?
Or would it be better to change format from datepicker to YYYY.MM.DD instead?

Answer 1

How about getting rid of the the substring stuff and using this instead?
SELECT TIME(DateFrom) AS `From`
FROM Calendar
WHERE DATE(DateFrom) = STR_TO_DATE($date,'%d.%m.%Y')
This will work because your DateFrom field happens to be stored in the standard string format of a DATETIME object.
From is in backticks because it's a reserved word.
You really should consider changing the data type of your DateFrom column to DATETIME, and then indexing that column. Then you can change your WHERE clause to this
WHERE DateFrom >= STR_TO_DATE($date,'%d.%m.%Y')
AND DateFrom < STR_TO_DATE($date,'%d.%m.%Y') + INTERVAL 1 DAY
and you will get a very great performance advantage.

Answer 2

This is how i finally solved it:
$date1 = 18.02.2014;
$date2 = 22.02.2014;
$a = explode('.',$date1);
$revdate1 = $a[2].'-'.$a[1].'-'.$a[0];
$newdate1 = str_replace(".","-",$revdate1);
$b = explode('.',$date2);
$revdate2 = $b[2].'-'.$b[1].'-'.$b[0];
$newdate2 = str_replace(".","-",$revdate2);
SELECT SUBSTRING(DateFrom FROM 1 FOR 10) AS Date,
SUBSTRING(DateFrom FROM 12 FOR 5) AS StartTime,
SUBSTRING(DateTo FROM 12 FOR 5) AS EndTime
FROM Calendar WHERE SUBSTRING(DateFrom FROM 1 FOR 10)
BETWEEN "'.$newdate1.'" AND "'.$newdate2.'"
I know DATETIME would be better but that was not an option here (not my database).
So this solution takes a date with format dd.mm.yyyy and reformats it to yyyy-mm-dd and checks it against the substring date from my table.
so the query prints all:
Date, StartTime, EndTime
between two dates