sql - Why does an int column values defaults to '0' when passed empty? -

i have table integer column.

create table [dbo].[tble1](     [id] [int] not null,     [test] [nchar](10) null ) 

when try insert values , pass empty string id column below, gets inserted , value of id column 0 default.

insert [dbo].[tble1]        ([id],[test])  values        ('','a') 

i couldn't find satisfying reasoning behind it. 1 please share thoughts on this?

what happening '' being converted integer. rules string can converted, based on digit characters in string.

if string empty, gets converted 0.

so, conversion happening @ "top" level. types don't match sql server attempts implicit conversion.

unfortunately, documentation not clear on topic:

character expressions being converted exact numeric data type must consist of digits, decimal point, , optional plus (+) or minus (-). leading blanks ignored. comma separators, such thousands separator in 123,456.00, not allowed in string.

to honest, interpret "must consist of digits" saying there must @ least 1 digit (although technically in english "zero" treated plural, don't think of plurals including 0 elements). however, empty string has been used -- pretty forever -- valid value type across broad range of databases.