How to return a value (by setting a variable) in dynamic SQL?

Question

DECLARE @sqlCommand nvarchar(1000)

DECLARE @countnumber int = 0

SET @sqlCommand = 'Set @countnumber = (SELECT count(*) from dsnv)'

EXEC (@sqlCommand)

print @countnumber ;

But i get error

Answer 1

use sp_executesql with output parameter

DECLARE @countnumber int = 0

SET @sqlCommand = 'Set @countnumber = (SELECT count(*) from dsnv)'

exec sp_executesql @sqlCommand, N'@countnumber int OUTPUT', @countnumber OUTPUT

print @countnumber ;