---DAY 4 --#15DAYSSQLCHALLENGE --Difference between count(*) and count(column_name) in SQL --Count(*) will count the null value --count(column_name) will not count the null value  ------------------------------START ------------------- SELECT REPLICATE('*',200) AS 'SOLUTION'  SELECT * FROM [dbo].[emp_2020]   SELECT * FROM  [dbo].[emp_2021] SELECT REPLICATE('*',200) AS 'JOIN THE ABOVE TWO TABLE WITH FULL OUTER JOIN '   SELECT *   FROM [dbo].[emp_2020] E_20 FULL   JOIN   [dbo].[emp_2021] E_21  ON E_20.emp_id=E_21.emp_id  SELECT  COUNT (* ) 'Count the no of records in the table' ,REPLICATE('*',200) AS 'COUNT (*) --count the null value '   FROM [dbo].[emp_2020] E_20 FULL   JOIN   [dbo].[emp_2021] E_21  ON E_20.emp_id=E_21.emp_id   SELECT  COUNT (e_21.designation) 'Count of designation'   ,REPLICATE('*',200) AS ' COUNT (COLUMN NAME)--Here it will not count t...