Question of the month January 2015 – which statement throws an error?

Consider the following statements

Statement 1:

Statement 2:

One of the above will throw an error. What is it and why?


Shortest method to extract decimal part

One of my friends told me that in an interview he was asked “What is the shortest method to extract only decimal part from a decimal number?”

One method I know is to find the remainder by dividing by 1 using modulus operator

declare @number decimal(12,2)
set @number=887.45
select @number as number,@number%1 as decimal_part

The result is

number       decimal_part
----------- --------------------
887.45       0.45

Preventing the usage of SELECT *

One of my friends asked “Is it possible to prevent users from using SELECT * from a table in the queries?” Well. The one way I can think of is to create a view that has all the columns from the table and add an extra column as an invalid derived expression.

Let us consider the following table

create table employee
emp_id char(10),
emp_name varchar(100),
dob datetime,
address varchar(100),
phone varchar(20)

insert into employee(emp_id,emp_name,dob,address,phone)
select 'EMP0000001','Madhivanan','20000101','Chennai,India','+91299200200'

You can now use * in the SELECT statement

select * from employee

To prevent this create the following view

create view emp_view
select *,cast('@@@' as datetime) as error_col from employee

Now you can not use SELECT * on this view

select * from emp_view

The above results to

Msg 241, Level 16, State 1, Line 1
Conversion failed when converting date and/or time from character string.

So you need to explicitly type out the required column names to get the data.

select emp_id,emp_name,dob,address,phone from emp_view

Continue reading Preventing the usage of SELECT *