SQL:
  1. Difference between Union and union all?
  2.  what is join?  explain its types?
  3. Difference between CTE,  temporary table and table variable
  4. Write down multiple CTE syntax?
  5. SELECT * FROM Table1, Table2
How many rows  above query will generate if table1 has 5 rows and table 2 has 10 rows
  1. Difference between Pivot and Unpivot?
  2. Multiple  ways to insert data in SQL table
  3. Define sequence and series for one example 
  4. How to remove duplicate records?
  5. How to replace male to female and female to male in single update query?
  6. What is the output of below query
 select case when null=null then 1 else 0 end
  1. What is wrong in below query?
Select year(employeejoindate) from emplyee where employeejoindate<2010

  1. There are two tables,  show unmatched records without using NULL
  2. What is output of query when we join 2 table and it has null value