SQL Server CONVERT(NUMERIC(18,0), '') fails but CONVERT(INT, '') succeeds?

sql sql-server numeric-conversion
Zachary Scott picture Zachary Scott · Nov 27, 2009 · Viewed 81k times · Source

PRINT CONVERT(NUMERIC(18,0), '')

produces Error converting data type varchar to numeric.

However,

PRINT CONVERT(INT, '')

produces 0 without error...

Question: Is there some SQL Server flag for this or will I need to do case statements for every varchar to numeric conversion? (aside from the obvious why?)

Answer

SqlACID picture SqlACID · Nov 27, 2009

Use ISNUMERIC 

declare @a varchar(20)
set @a = 'notanumber'
select case when isnumeric(@a) = 0 then 0 else convert(numeric(18,0),@a) end

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