Question

im using a v simple database and i have 3 columns A(bigINT 20) , B(bigInt 20) and c(DECIMAL(5,4)) , when i fire the following query i get the below mentioned results :

REPLACE INTO `my_table` SET `A` = 8,`B` = 44,`C` = 14;

i get these values in mysql A =8 , b= 44 and c as 9.9999 ! ?

any ideas as to why is this happening and what can i do to resolved this ?

Answer 1

DECIMAL(5,4) means that the number has at most 5 digits, 4 of them after decimal point. So 14 is simply overflow as it would require DECIMAL(6,4).

It must be cleared that 14 is overflow, because as constant precision point decimal it is internally 14.0000 here (so six digits over five).

So if you try to put 14.0000 (six digits) in DECIMAL(5,4) (five digits max) -> MySQL chooses value closest to the one you request. Therefore 14.0000 gets “rounded” to 9.9999.

To fit 14 in your column you can either extend it do DECIMAL(6,4) (to allow more digits in general) or change to DECIMAL(5,3) (which will allow one more digit before decimal point, but loses some precision of course).