Skip to main content

Difference between the having clause and where clause in sql server

Similar:
1) Where Vs Having in sql server
2) Having vs Where which is better in sql server.

The main difference between Where clause and Having Clause is that Having is allays use with the group by statements  while Where is used with the Whole query.

Having Filter the data in a group not the whole result set while Where filter the data in whole result set.

Ex:
Group Of 'Empid'
--Finding Duplicate Data 

Select Empid, COUNT(*) AS NoOfDuplicateRecord  From tblEmployeedetails Group by Empid Having COUNT(*) >1

Most of the time you will get the same result with Where or Having
The below given two SQL command produces the same result set.

1) Select Empid , SUM(Salary) From tblEmployeedetails Group By DeptId having Deptid='D0000234'

2) Select Empid , SUM(Salary) From tblEmployeedetails Where Deptid='D0000234' Group By DeptId

But don't confuse some time it may be but not all time as the given Example.

EmpidDepIdSalary
E001 D00120000
E002D00122000
E003D00218000
E004D00219000
E005D00220000
E006D00321000
E007D00330000

Select Empid , SUM(Salary) From tblEmployeedetails  Group By DeptId Having SUM(Salary) >30000

This Work can only done by having clause not through Where clause.
Where clause doesn't work with aggregate functions.

Popular posts from this blog

how $document.ready() is different from window.onload()

we often use window.onload() in javascript and $document.ready() in jquery and assume that both are same just jquery library wrap up javascript window.onload() and introduce $document.ready() but no there is much difference between them below is the explanation -

Merging multiple PDFs using iTextSharp in asp.net c#

In this article i will show you how to merge multiple pdfs into one using ITextSharp below is the two approach one is to pass your input files path, output file path (will be created if not exist) and another is pass direct input stream, output stream and it will write the merge files into output stream.

How to handle click event of linkbutton inside gridview

Recently I have posted how to sort only current page of gridview , Scrollble gridview with fixed header through javascript , File upload control inside gridview during postback and now i am going to explain how to handle click event of linkbutton or any button type control inside gridview. We can handle click event of any button type control inside gridview by two way first is through event bubbling and second one is directly (in this type of event handling we need to access current girdviewrow container)

How to validate dropdownlist in JavaScript

In this article you will see how to put validation in dropdownlist by javascript, suppose first item value of dropdownlist is 0 and text is "-Select-" just like given below and we have to validate that at least one item is selected excluding default i.e "-Select-".