Different ways to replace NULL in SQL SERVER

Different ways to replace NULL in SQL SERVER

Consider the Employees table below.

Write a LEFT OUTER SELF JOIN query, which produced the following output.

In the output, MANAGER column, for Todd's rows is NULL. I want to replace the NULL value, with 'No Manager'

Replacing NULL value using ISNULL() function: We are passing 2 parameters to IsNULL() function. If M.Name returns NULL, then 'No Manager' string is used as the replacement value.

SELECT E.Name as Employee, ISNULL(M.Name,'No Manager') as Manager

FROM tblEmployee E

LEFT JOIN tblEmployee M

ON E.ManagerID = M.EmployeeID

Replacing NULL value using CASE Statement:

SELECT E.Name as Employee, CASE WHEN M.Name IS NULL THEN 'No Manager'

   ELSE M.Name END as Manager

FROM  tblEmployee E

LEFT JOIN tblEmployee M

ON   E.ManagerID = M.EmployeeID

Replacing NULL value using COALESCE() function: COALESCE() function, returns the first NON NULL value :

SELECT E.Name as Employee, COALESCE(M.Name, 'No Manager') as Manager

FROM tblEmployee E

LEFT JOIN tblEmployee M

ON E.ManagerID = M.EmployeeID