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  • Is count(*) really expensive ?

    - by Anil Namde
    I have a page where I have 4 tabs displaying 4 different reports based off different tables. I obtain the row count of each table using a select count(*) from <table> query and display number of rows available in each table on the tabs. As a result, each page postback causes 5 count(*) queries to be executed (4 to get counts and 1 for pagination) and 1 query for getting the report content. Now my question is: are count(*) queries really expensive -- should I keep the row counts (at least those that are displayed on the tab) in the view state of page instead of querying multiple times? How expensive are COUNT(*) queries ?

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  • How to avoid geometric slowdown with large Linq transactions?

    - by Shaul
    I've written some really nice, funky libraries for use in LinqToSql. (Some day when I have time to think about it I might make it open source... :) ) Anyway, I'm not sure if this is related to my libraries or not, but I've discovered that when I have a large number of changed objects in one transaction, and then call DataContext.GetChangeSet(), things start getting reaalllly slooowwwww. When I break into the code, I find that my program is spinning its wheels doing an awful lot of Equals() comparisons between the objects in the change set. I can't guarantee this is true, but I suspect that if there are n objects in the change set, then the call to GetChangeSet() is causing every object to be compared to every other object for equivalence, i.e. at best (n^2-n)/2 calls to Equals()... Yes, of course I could commit each object separately, but that kinda defeats the purpose of transactions. And in the program I'm writing, I could have a batch job containing 100,000 separate items, that all need to be committed together. Around 5 billion comparisons there. So the question is: (1) is my assessment of the situation correct? Do you get this behavior in pure, textbook LinqToSql, or is this something my libraries are doing? And (2) is there a standard/reasonable workaround so that I can create my batch without making the program geometrically slower with every extra object in the change set?

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  • Only show certain items in a mysql database using php and time()

    - by Jon
    Is there a way to only show the items that are older than a certain date in a php mysql array? I'm using this query method and sorting by lastpost_cl: $query="SELECT * FROM properties ORDER BY lastpost_cl"; $result=mysql_query($query); $num = mysql_num_rows ($result); mysql_close(); and I was thinking the way of checking the time would be: if (time() <= strtotime($lastpost_cl)) { } How can I combine the two and only show lastpost_cl that are older that the current time?

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  • Change an autoincrementing field to one previous

    - by jlan
    One day, wordpress suddenly jumped from pots id 9110 to 890000000 post. Days later I'd like to move back new posts to continue from id 9111. I'm sure that id will never reach id 890000000, no problem here, but id is an autoincrement field and "ALTER TABLE wp8_posts AUTO_INCREMENT =9111" is not working. Can I force id to continue from 9111 ?

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  • How should I build a gaming community

    - by Przystojny
    I've been wanting to build my own gaming community site (like http://fragbite.com) for a long time, I have started many times but just quitted after a couple days because it gets very messy I've been palying around with php and mysql off and on for 3 years but i've never gotten in to oop. i have tried but i usually end up with the "old php". I usually build my pages like so that i include a file on top of all pages with neccasary functions, html head etc. And I mix php and html together which I dont mind but if I eventually would get a designer he would not like it i think. I have tried both phpcake and codeigniter and all those popular mvc's but its just to much, like they do all the work. i want to do it myself. but i dont know where to start. What would you do if you were me? Is there maybe some non-oop mvc? (Sorry for my english)

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  • How efficient is a details table?

    - by Jeffrey Lott
    At my job, we have pseudo-standard of creating one table to hold the "standard" information for an entity, and a second table, named like 'TableNameDetails', which holds optional data elements. On average, for every row in the main table will have about 8-10 detail rows in it. My question is: What kind of performance impacts does this have over adding these details as additional nullable columns on the main table?

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  • move data from one table to another, postgresql edition

    - by IggShaman
    Hi All, I'd like to move some data from one table to another (with a possibly different schema). Straightforward solution that comes into mind is - start a transaction with serializable isolation level; INSERT INTO dest_table SELECT data FROM orig_table,other-tables WHERE <condition>; DELETE FROM orig_table USING other-tables WHERE <condition>; COMMIT; Now what if the amount of data is rather big, and the <condition> is expensive to compute? In PostgreSQL, a RULE or a stored procedure can be used to delete data on the fly, evaluating condition only once. Which solution is better? Are there other options?

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  • getting complete sql query in jython

    - by kdev
    result=sqlstring.executeQuery("select distinct table_name,owner from all_tables ") rs.append(str(i)+' , '+result.getString("table_name")+' , '+result.getString("owner")) If i want to display the query select * from all_tables or ' select count(*) from all_tables' how can i get the output to display . Please suggest thanks

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  • Whatz wrong with this MSSQl Query ?

    - by ClixNCash
    Whatz wrong this MSSQl Query : Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click Dim SQLData As New System.Data.SqlClient.SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True") Dim cmdSelect As New System.Data.SqlClient.SqlCommand("SELECT COUNT(*) FROM Table1 WHERE Name ='" + TextBox1.Text + "'", SQLData) SQLData.Open() If cmdSelect.ExecuteScalar > 0 Then Label1.Text = "You have already voted this service" Return End If Dim con As New SqlConnection Dim cmd As New SqlCommand con.Open() cmd.Connection = con cmd.CommandText = "INSERT INTO Tabel1 (Name) VALUES('" & Trim(Label1.Text) & "')" cmd.ExecuteNonQuery() Label1.Text = "Thank You !" SQLData.Close() End Sub

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  • Using Linq, how to separate a list in to grouped objects by name?

    - by Dr. Zim
    I have a table where a record looks like this varchar(255) Name varchar(255) Text varchar(255) Value Name is the DDL name, Text is what is displayed, and Value is returned upon selection. There are between one and twenty options for each Name. Without iterating though each option like a cursor, is there any way to pull out a list of objects, one for each unique DDL Name, using Linq and C#? A sample of the data: Beds '4 (10)' 4 Beds '5 (1)' 5 Beds '7 (1)' 7 Baths 'NA (13)' NULL Baths '0 (1)' 0 Baths '1 (13)' 1 I was thinking about doing an outer select to get the unique Names, then an inner select to get the list of options for it, then return the set as a List of a set of Lists.

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  • How can I bind an Enum to a DbType of bit or int?

    - by uriDium
    Hi I am using Linq2Sql and want to bind an objects field (which is enum) to either a bit or a int type in the database. For example I want have a gender field in my model. I have already edited the DBML and changed the Type to point to my enum. I want to create Radio buttons (which I think I have figured out) for gender and dropdown lists for other areas using the same idea. My enum looks like this public enum Gender { Male, Female } Mapping between DbType 'int' and Type 'Project.Models.Gender' in Column 'Gender' of Type 'Candidate' is not supported. Any ideas on how to do this mapping. Am I missing something on the enums.

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  • Updating Database From Dataset?

    - by Ases
    I wanna update my database from my dataset. mydataadapter = new MySqlDataAdapter("SELECT * FROM table0; SELECT * FROM table1; SELECT * FROM table2;", con); myda.Fill(dataset); //...... // for example I'm doing a change like this ds.Tables[2].Rows[1][3] = "S"; //Then updating the database MySqlCommandBuilder com = new MySqlCommandBuilder(mydataadapter); mydataadapter.Update(dataset, "table2"); then it returns this error TableMapping['table2'] or DataTable 'table2' didn't find by Update. Do you have any advice?

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  • Query to find duplicate item in 2 table

    - by Rico
    I have this table Antecedent Consequent I1 I2 I1 I1,I2,I3 I1 I4,I1,I3,I4 I1,I2 I1 I1,I2 I1,I4 I1,I2 I1,I3 I1,I4 I3,I2 I1,I2,I3 I1,I4 I1,I3,I4 I4 AS you can see it's pretty messed up. is there anyway i can remove rows if item in consequent exist in antecedent (in 1 row) for example: INPUT: Antecedent Consequent I1 I2 I1 I1,I2,I3 <---- DELETE since I1 exist in antecedent I1 I4,I1,I3,I4 <---- DELETE since I1 exist in antecedent I1,I2 I1 <---- DELETE since I1 exist in antecedent I1,I2 I1,I4 <---- DELETE since I1 exist in antecedent I1,I2 I1,I3 <---- DELETE since I1 exist in antecedent I1,I4 I3,I2 I1,I2,I3 I1,I4 <---- DELETE since I1 exist in antecedent I1,I3,I4 I4 <---- DELETE since I4 exist in antecedent OUTPUT: Antecedent Consequent I1 I2 I1,I4 I3,I2 is there anyway i can do that by query?

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  • MySQL: selecting totals as three fields from same table as one query?

    - by coderama
    I have a table with various orders in it: ID | Date | etc... 1 | 2013-01-01 | etc 2 | 2013-02-01 | etc 3 | 2013-03-01 | etc 4 | 2013-04-01 | etc 5 | 2013-05-01 | etc 6 | 2013-06-01 | etc 7 | 2013-06-01 | etc 8 | 2013-03-01 | etc 9 | 2013-04-01 | etc 10 | 2013-05-01 | etc I want a query that ends wit the result: overallTotal | totalThisMonth | totalLastMonth 10 | 2 | 1 But I want to do this in one query! I am trying to find a way to use subqueries to do this. SO far I have: SELECT * from ( SELECT count(*) as overallTotal from ORDERS ) How can I combine this with other subqueries so I can get the totals in one query?

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  • possible way to attach database to exe

    - by ali
    i created a small application using c# winforms that uses mssql as a database. is there a way to attach the database to the exe file so i won't need to install sqlserver on all the machines that i want to run the program on?

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  • Maintaining stored procedures in source control

    - by dub
    How do you guys maintain your stored procedures? I'd like to keep versions of them for a few different reasons. I also will be setting up cruisecontrol.net and nant this weekend to automate builds. I was thinking about coding something that would generate the create scripts for all tables/sprocs/udf/xml schemas in my development database. Then it would take those scripts and update them in source control every couple hours.... Ideally, I'd like to make this some sort of plugin/module for cruisecontrol.net. Any other ideas?

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  • FOSS version of SQLCompare or something similar?

    - by Scott
    Actually, free is good enough, it doesn't have to be open source :) I'm currently using the Schema Compare utility of VS2008, but it doesn't have a command line interface and has some other weaknesses as well. I'm wondering what free tools others are using to provide command line schema comparisons/synchronizations? Thanks.

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  • How to go about writing this classic asp in asp.net

    - by Phil
    I am stuck in converting this snipped to asp.net. set RSLinksCat = conn.Execute("select linkscat.id, linkscat.category from linkscat, contentlinks, links where contentlinks.linksid = links.id and contentlinks.contentid = " & contentid & " and links.linkscatid = linkscat.id order by linkscat.category") <%if not RSLinksCat.EOF then%><h1>Links</h1> <br /> <%do while not RSLinksCat.EOF%> <%set RSLinks = conn.Execute("select * from links where linkscatid = " & RSLinksCat("id") & "")%> <strong><%=RSlinkscat("category")%><strong> <ul> <%do while not RSlinks.EOF%> <li> <a href = "http://<%=RSLinks("url")%>" target="_blank"><%=RSlinks("description")%></a> </li> <%RSLinks.MoveNext loop%> </ul> <%RSLinksCat.MoveNext loop%> <br /> <%end if%><%conn.close%> I'm not sure where to start. Can anyone recommend the correct approach i.e sqldatareaders or repeaters or arrays or? VB code samples most welcome. Thanks

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  • Calendar using Javascript/ PHP/ mySQL

    - by Gushiken
    for a current webapp i need a "outlook-like" calendar... Here are some requirements for the calendar: week-view for the appointments different appointment types direct display of the length and time of the date (like in googleCalendar) multiple appointments for the same time only using javascript, php and any DB We need the calendar for the Zend Framework, so if the Calendar doesn't already support the ZF, the source needs to be editable! do you know any calendar which fits my needs? or do you have any tipps for developing one by myself?

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