Difference between count (*) and count (1) in SQL server

Question

1.00/5 (2 votes)

See more:

difference between count(1) and count(*) with example.

What I have tried:

difference between count(1) and count(*) with example

Posted 2-Apr-18 2:44am

sudhakarthikeyan

Updated 7-May-18 5:05am

Add a Solution

Comments

Christiaan van Bergen 2-Apr-18 8:48am

Dude, really? http://lmgtfy.com/?q=count(1)+and+count(*)

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Wendelius · Answer 1 · 2018-04-02T03:58:00

There used to be a time when it was relevant what you had inside COUNT or what expression you used in an EXISTS structure.

In the old ages the optimizer wasn't necessarily smart enough to eliminate the row retrieval if a column was used in such expression. This caused an unnecessary disk or memory I/O operation to the table when the data itself was irrelevant to the query.

However, this was a time just before dinosaurs were extinct so any modern optimizer recognizes this situation and understands not to fetch the actual record. I could imagine there are some database products that are in their early stages and suffer from these kinds of problems but if we're talking about the mainstream databases then the answer is easy: No difference.

Member 12904962 · Answer 2 · 2018-05-07T05:07:00

no existe una diferencia entre estos dos tipos de consultas

select count(*) y count(1) => son iguales, es decir si tenemos una tabla con 5 registros en los dos casos nos va dar 5.

SQL

create table #tabla (student varchar(50), id int)
insert into #table (student,id)
values('Camila',1111)
     ,('Andres',2222)
     ,('Maria',null)
     ,('Jose',null) 
     ,('Pedro',3333)

select count(*) from #tabla
-- result 5

select count(1) from #tabla 
-- result 5

select count(id) from #tabla
-- result 3

espero poder ayudarte...

Difference between count (*) and count (1) in SQL server

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0