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I have the following code:
SELECT <column>, count(*) FROM <table> GROUP BY <column> HAVING COUNT(*) > 1;
Is there any difference to the results or performance if I replace the COUNT(*) with COUNT('x')?
(This question is related to...
Started by Andrew on
, 6 posts
by 6 people.
Answer Snippets (Read the full thread at stackoverflow):
Select count(*) from table
I'm not sure question, it was asked what....
The-difference-between-countcolumn-and-count
The major performance difference is that COUNT(*) can will return immediately, without needing to examine any rows.
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Hi, just wondering if any of you guys use Count(1) over Count(*) and if there is a noticeable difference for SQL Server 2005 in performance? Or is this just a legacy habit that has been brought forward from days gone past?
Started by Nai on
, 9 posts
by 9 people.
Answer Snippets (Read the full thread at stackoverflow):
That said, I've always used ....
There is no point in loading the DB engine with more work if you're .
Count(1) -- counts number of records based on just first columnI prefer using COUNT (1).
Of records based on all columns.
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Is there a difference between the following queries, assuming there is a primary field 'id' in the table (as in speed, etc)?
SELECT COUNT(id) FROM table
vs.
SELECT COUNT(*) FROM table
Started by James Simpson on
, 6 posts
by 6 people.
Answer Snippets (Read the full thread at stackoverflow):
Will recognize the count( ) construct and just count the rows without building an intermediate result bufferNot in MySQL, no, it has optimized the COUNT well (assuming that your id field is already a PK --which is fairly self....
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I thought LINQ to SQL was tuned for performance?
The following LINQ to SQL for counting is very poor
Dim uniqueFactors As Integer = db.LargeTable.Distinct.Count
produces:
SELECT COUNT(*) AS [value] FROM [dbo].[LargeTable] AS [t0] WHERE ([t0].[ID] % @p...
Started by Coppermill on
, 4 posts
by 4 people.
Answer Snippets (Read the full thread at stackoverflow):
The SELECT COUNT(*) is the only way SQL Server (and therefore LINQ) can give you an exact, up-to-date count of the ....
Since the primary key is unique, why not just:
int count for larger tables.
Normal TSQL that perfoms ok...
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Hi all ,
i am facing some problem with files with huge data. i need to skip doing some execution on those files. i get the data of the file into a variable. now i need to get the byte of the variable and if it is greater than 102400 , then print a message...
Started by randeepsp on
, 6 posts
by 6 people.
Answer Snippets (Read the full thread at stackoverflow):
Terms, this answer may still be relevant:
Just open the file in binary mode
f = open(filename, 'rb() :
import os.path if os.path.getsize('f') <= 102400: doit();
Just check the length of the string.
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In other words, how does the implementation keeps track of the count?
Is there a map-like object maintained which is accessible by all the shared_ptr instances whose key is the pointer's address and value is the number of references? If I've to implement...
Started by vito on
, 8 posts
by 8 people.
Answer Snippets (Read the full thread at stackoverflow):
When you make copy of shared_ptr object it copy pointer with count of references, increase pointers is very easy....
Shared_ptr just keep one additional pointer for reference counting.
Of questions by looking at the source code.
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Hi , I don't know whether this is correct forum for sql query, but i have stucked that's why asked question. Highly sorry for that.
In my sql query, i just need to check whether dataexist for perticular userid.
Here always, only one row will return when...
Started by Hemant Kothiyal on
, 7 posts
by 7 people.
Answer Snippets (Read the full thread at stackoverflow):
You can also use COUNT(1/0)
It depends what the second....
The optimiser (SQL Server at least) realises COUNT(1) is trivial.
With count(column) it just returns the total number of rows in the table.
Is null or not in each row.
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Hey guys i wanted to know, will i run into any concurrency problem with this? This is NOT in a transaction. This code is for Sqlite(prototype), but i plan to use it with either MySql or a SQL from MS
command.CommandText = "UPDATE tag_name SET count = ...
Started by acidzombie24 on
, 5 posts
by 5 people.
Answer Snippets (Read the full thread at stackoverflow):
If you change TRANSACTION ISOLATION LEVEL, it should work just fine, at least on SQLServer..
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I started with a query:
SELECT strip.name as strip, character.name as character from strips, characters, appearances where strips.id = appearances.strip_id and characters.id = appearances.character.id and appearances.date in (...)
Which yielded me some...
Started by James A. Rosen on
, 7 posts
by 7 people.
Answer Snippets (Read the full thread at stackoverflow):
If MySQL supports Analytics/Window Functions, then:
select bar, yoo, count(yoo) over, (select count(yoo) from t t2 ....
On an RDBMS system, I'd select the count query into a temporary table, then rejoin the temp table tables, though.
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A Wish. Just one. Make it count.
http://i594.photobucket.com/albums/t...inks/kubey.jpg
Started by Kerrus on
, 25 posts
by 21 people.
Answer Snippets (Read the full thread at spacebattles):
Does it count that I'm.
That is quite possibly the most wanked power ever.
Then i run and hide from it.
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