mysql - MAX(Column) returns me a wrong value -


i want retrieve maximum invoice number invoice table returns following when select records can see maximum invoice no "10".

select * invoice

enter image description here

but when query for

select max(invoice_number) maxinv invoice

it returns me "9". why that?

enter image description here

this situation can occur if invoice_number stored text column e.g. varchar(10). in case, based on alphabetical order, 9 maximum value.

ideally, should storing values on want perform numerical operations numeric datatypes e.g. int. however, if reason cannot change column datatype, can try casting column before applying max, so:

select max (convert(invoice_number, signed integer)) maxinv invoice

note: mention "values on want perform numerical operations" because there cases input text entirely numeric, such phone numbers or perhaps credit card numbers, there no scenario in want add 2 phone numbers, or take square root of credit card number. such values should stored text.


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