Compare if value is within range of number mysql - php

Question

In my database i have 2 columns namely: Min and Max they are varchar and they have number values which i need to compare with. My query is something like this
SELECT * FROM Pricing_tbl WHERE Productid='10'
and i have this to compare the price
while ($selected_row = $stmt - > fetch(PDO::FETCH_ASSOC)) {
if ($marketval > $selected_row['Min'] && $marketval < $selected_row['Max']) {
$price[] = array('price_level' => $selected_row['price_level']);
}
}
This is ok if values of Min and Max are always numbers. But there is an instance where the value of Max is above. How to compare this situation?
Example values will be
Or should i just change the Max value. Any suggestion is appreciated

Answer 1

Assuming a maximum of above means all the way to infinity and you want to keep the data as is 1, you can just change the condition:
$marketval > $selected_row['Min'] && $marketval < $selected_row['Max']
into something like:
$marketval >= $selected_row['Min'] &&
($selected_row['Max'] == 'above' || $marketval < $selected_row['Max'])
In other words a value is considered under the maximum always if the maximum is the word above. Otherwise the actual (original) comparison decides.
PHP short-circuiting on logical operators will ensure that the second half of the or section will never be evaluated if the first half is true.
Note the change I made to the minimum comparison as well, the use of >= rather than >. As it was, a value like 300000.01 would not have been caught.
You may also want to coerce the numerics in the comparisons with $marketValue. If both $marketValue and $selectedRow['whatever'] are strings, I think they'll still use numeric comparison but I usually try to be explicit so I don't have to think about it :-)
1 There are probably better ways to do this, other than storing what's mostly numeric data as strings just because you want to be able to store the value 'above'.
Both methods below involve converting the column type to a numeric one which will allow better comparisons, including having the DBMS itself work it out rather than having to get all data and post-process it with PHP. Data manipulation is what a DBMS does best so it's generally better to leave that manipulation up to the DBMS for efficiency.
The first is to put a ridiculously large number in the maximum for the 'above' row so that your simple 'in between min and max' check will work. Using the DBMS itself to get the pricing level would be a simple:
select pricing_level
from pricing_tbl
where product_id = '10'
and $market_val >= minval
and $market_val < maxval
That will give you a single row containing the correct pricing level.
The second is to store NULL in that column instead of a string. A nullable numeric column will still work with a slight modification:
select pricing_level
from pricing_tbl
where product_id = '10'
and $market_val >= minval
and ($market_val < maxval or maxval is null)
In both those cases, you may want to translate the upper region (large number or null) to and from the word above when presenting or editing the table itself. This will make the process look the same even though the underlying data has changed.

Answer 2

i have 2 columns namely: Min and Max they are varchar
this is wrong. It should be int or at least decimal values
My query is something like this
this is wrong. Your query should include $marketval to do all the calcs on the database side.
here is an instance where the value of Max is above.
this is wrong. No numerical column should ever contain a string. you can store a big number there. or a NULL, but not a string.