结合字母数字时如何选择真实值？

Question

mysql: customer_number = int (cannot be changed)

$query = "SELECT * FROM clients WHERE customer_number= '123F'" 

The RESULT should be empty.

The query has a result which is incorrect because, MySQL ignore any alphabet character which form part of the value with an integer datatype, eg.'F'

Answer 1

You can check if the value provided is strictly integer.

$query = "SELECT * FROM clients WHERE customer_number= '123F' 
AND '123F' REGEXP '^-?[0-9]+$'";

AND needs both conditions compulsorily.

So, even if MySQL ignores F from 123F and treats it as 123 , second condition will return FALSE and 123F will fail regular expression of strictly integer condition.

This will have following results:

123 -> pass

123F -> fail

Answer 2

You can cast customer_number to string:

SELECT *
FROM clients
WHERE CAST(customer_number as CHAR(50)) = '123F'

The above query is of course not SARGable. Consider processing the comparison argument on the client side before the construction of the query.

Demo here

Answer 3

Or check as first condition if the integer from the string equal the string (change the string to your fieldname) :

SELECT * FROM clients 
WHERE
  '123F'+0 = '123F' 
AND
  customer_number= '123F';