SQL: IF clause within WHERE clause                     
                        
                           
                           
                        
                     
                  
                  
                  Is it possible to use an IF clause within a WHERE clause in MS SQL?
Example:
WHERE
IF IsNumeric(@OrderNumber) = 1
OrderNumber = @OrderNumber
ELSE
OrderNumber LIKE '%' + @OrderNumber + '%'
To use an IF clause within a WHERE clause, you can try using the CASE statement like this: 
WHERE OrderNumber LIKE
  CASE WHEN IsNumeric(@OrderNumber) = 1 THEN 
    @OrderNumber 
  ELSE
    '%' + @OrderNumber
  END
 
 
