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  • which sql query is more efficient: select count(*) or select ... where key>value?

    - by davka
    I need to periodically update a local cache with new additions to some DB table. The table rows contain an auto-increment sequential number (SN) field. The cache keeps this number too, so basically I just need to fetch all rows with SN larger than the highest I already have. SELECT * FROM table where SN > <max_cached_SN> However, the majority of the attempts will bring no data (I just need to make sure that I have an absolutely up-to-date local copy). So I wander if this will be more efficient: count = SELECT count(*) from table; if (count > <cache_size>) // fetch new rows as above I suppose that selecting by an indexed numeric field is quite efficient, so I wander whether using count has benefit. On the other hand, this test/update will be done quite frequently and by many clients, so there is a motivation to optimize it.

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  • Autohotkey to map F5 to Shift+Home and then F5 - eventually executing a single line query in sql server?

    - by puretechy
    Reading the syntax from autohotkey, I am trying to achieve this. But the first step of selecting the entire line is not working:- F5:: send {Shift Home} return I have tried few others too, but its not working. This is not sending Shift+Home combination on pressing F5 key. Please tell me what's wrong with this? Also if possible, what to do next?, as if I will write send {F5} I believe, it will recursively fire this script again and again..

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  • SQL Reporting Services 2005 - Date field based on a user entered date?

    - by Pierce
    Hi, I have a report in report services 2005 that has two date fields. The problem is that if users run this for a large section of time it uses too much resources on our server. It is possible to only allow the end user to enter the start date and then the end date be auto populated/derived from this field (for example they enter the 1st of a month and this automatically change the end date to the last of a month.)

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  • Can you define values in a SQL statement that you can join/union, but are not stored in a table outs

    - by Mervyn
    I'm trying to create a query and need to join against something that I can define values in without creating a table. I'll attempt to describe what I'm trying to do: table1 is joined on field a with table2 (titles for FK in table 1) - Table1 has values outside of what exists in table2 - I want to add an additional 'table' to be unioned with table2 and then joined with table 1 Thanks

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  • PHP arrays & keys - fetching particular ones

    - by Rohan
    Hi Lets say I have an array with a structure like this: $arr= Array( array( "id"=>"a" "type">"apple"), array( "id"=>"b"), array( "id"=>"c"), array( "id"=>"c" "type"=>"banana") ); now I want to have a foreach loop which fetches all the array elements which have a key in them named "type". Something like foreach(all arrays which have type in them as $item) How would I do that? many thanks.

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  • How many SQL queries per HTTP request is optimal?

    - by Chris Kooken
    I know the answer to this question for the most part is "It Depends", however I wanted to see if anyone had some pointers. We execute queries each request in ASP.NET MVC. Each request we need to get user rights information, and Various data for the Views that we are displaying. How many is too much, I know I should be conscious to the number of queries i am executing. I would assume if they are small queries and optimized out, half-a-dozen should be okay? Am I right? What do you think?

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  • [Linq to sql] query result what should i use Count() or Any()...

    - by Pandiya Chendur
    I am checking login of a user by this repository method, public bool getLoginStatus(string emailId, string password) { var query = from r in taxidb.Registrations where (r.EmailId == emailId && r.Password==password) select r; if (query.Count() != 0) { return true; } return false; } I saw in one of the previous questions !query.Any() would be faster... Which should i use? Any suggestion....

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  • sql: how to use count for a particular column ,(or) to count a particular column by its field name

    - by Aravintha Bashyam
    in my query i need a to count a particular column by its field name, SELECT C.INC_COUNT, MIN_X, MIN_Y, MAX_X, MAX_Y, B.STATE_ABBR, B.STATE_NAME, B.LATITUDE, B.LONGITUDE, A.STATE, GEO_ID, concat(A.LSAD_TRANS,' ' , A.NAME) DIST_NAME, A.LSAD, GeometryType(SHAPE) GEO_TYPE, AsText(SHAPE) GEOM from SHAPE_LAYERS A join SHAPE_LAYER_STATE_DESC B on ( A.state = B.state) left outer join INC_DIST_SUMMARY_ALL C on (C.SHAPE_GEO_ID = A. GEO_ID) here i have to count by B.STATE_NAME ,C.INC_COUNT if exmple the field name nevada means i have to get all neveda value count and the C.INC_COUNT.

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  • SQL query to get lowest 2 values of a counted query selection (using db2)?

    - by jNoob
    Hi, Imagine I already have a query that returns the following: Col1 | Col2 ------------ A | 2 B | 3 C | 3 D | 4 E | 8 ... Say I used something like this: select Col1, count ( * ) as Col2 \ from ... where ... order by Col2 \ group by Col1 \ So now, all I want to select are (Col1, Col2) such that it returns the selections (a, b) and (c, d) where (b >= all (Col2)) and (d >= ((all (Col2)) - a)). So for the above example, it would return {(A, 2), (B, 3), (C, 3)}. How do I go about doing this? Any help would be highly appreciated. Thanks.

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  • MSSQL 2005 Snapshot Agent Uses 100% CPU

    - by matth1jd
    When setting up a new subscription to a publication (transactional replication) from 64-bit SQL Server 2005 to 64-bit SQL Server 2005 the Snapshot Agent on the publisher consumes 100% of the CPU. I am using SSMS to create the new subscription. My initial impression is that this could be from row locking occurring during the generation of the snapshot but I have read that a concurrent snapshot is generated by default in SQL Server 2005, and that row locking shouldn't be a concern. As this is a production server I would like to be able to initialize replication without bringing the box to it's knees. Any suggestions would be helpful and appreciated.

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  • PHP SQL, SELECT corresponding data from 3 tables at once?

    - by user346325
    I have 3 tables, 'u' 'd' 's' 'u' has userid divid 'd' has divid divname 's' has sname primaryuserid secondaryuserid Now what I'd like to do is display a table with rows of the following format userid, divname, sname Plus figure out a way to decipher whether userid is a primary or secondary for this sname table. I'm able to show userid and divname using a left join, but I don't know how I would add a third table? To make it trickier, there can be more than 1 snames for each userid, up to ~20. Is there a way to display 0-20 snames depending on the userid, seperated with commas?

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  • SQL & PHP - Which is faster mysql_num_rows() or 'select count()'?

    - by Joel
    I'm just wondering which method is the most effective if I'm literally just wanting to get the number of rows in a table. $res = mysql_query("SELECT count(*) as `number` FROM `table1`"); $count = mysql_fetch_result($res,0,'number'); or $res = mysql_query("SELECT `ID` FROM `table1`"); $count = mysql_num_rows($res); Anyone done any decent testing on this?

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  • sqlserver.exe uses 100% CPU

    - by Markus
    I've created an application (asp.net) that once a day syncs an entire database through XML-files. The sync first creates an transaction and then clears the databases tables and then starts to parse and insert the new rows into the database. When all the parsing is complete it commits the transaction. This works fine on a SQL Server 2005 (on another machine), but on SQL Server 2005 Express, the process starts to use 100% CPU after a while, and as I log the inserts being made I can see that it just stops inserting. No exception, it just stops inserting. Anyone got any idea what this may be? I've previously run the syncronization on another sql 2005 express (also on another computer), and that worked. The server has only 2GB RAM, could this be the problem?

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