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• MySQL query with JOINS and GROUP BY

  - by user1854049

  I'm building a MySQL query but I can't seem to get it right. I have four tables: - customers - orders - sales_rates - purchase_rates There is a 1:n relation 'customernr' between customers and orders. There is a 1:n relation 'ordernr' between orders and sales_rates. There is a 1:n relation 'ordernr' between orders and purchase_rates. What I would like to do is produce an output of all customers with their total purchase and sales amounts. So far I have the following query. SELECT c.customernr, c.customer_name, SUM(sr.sales_price) AS sales_price, SUM(pr.purchase_price) AS purchase_price FROM orders o, customers c, sales_rates sr, purchase_rates pr WHERE o.customernr = c.customernr AND o.ordernr = sr.ordernr AND o.ordernr = pr.ordernr GROUP BY k.bedrijfsnaam The result of the sales_price and purchase_price is far too high. I seem to be getting double counts. What am I doing wrong? Is it possible to perform this in a single query? Thank for your response!

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• Performance problem on a query.

  - by yapiskan

  Hi, I have a performance problem on a query. First table is a Customer table which has millions records in it. Customer table has a column of email address and some other information about customer. Second table is a CommunicationInfo table which contains just Email addresses. And What I want in here is; how many times the email address in CommunicationInfo table repeats in Customers table. What could be the the most performer query. The basic query that I can explain this situation is; Select ci.Email, count(*) from Customer c left join CommunicationInfo ci on c.Email1 = ci.Email or c.Email2 = ci.Email Group by ci.Email But sure, it takes about 5, 6 minutes in execution. Thanks in Advance.

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• Multiple &(AND) fails in query

  - by N e w B e e

  here is my query $sql = 'SELECT * FROM Orders INNER JOIN [Order Details] ON Orders.OrderNumber = [Order Details].OrderNumber WHERE Orders.CartID =2 AND [Order Details].Option10 Is Null AND [Order Details].Status="Shipped"'; this queries when entered in MS_Access sql view, returns the correct results, but when I copy and paste the same query in my php script, it fails and gives the error Too few parameters, expected 1... although data is there, query is working in access... Please note if I omitted on AND condition, it works eg if I removed shipped conidtion or is null condition, it works then too.. any hint? whats wrong with it?? any help?thanks

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• Query to select from two different tables

  - by ryan

  I would like to select from two tables and display my result using this query: CREATE TABLE Buy_Table ( buy_id int identity primary key, user_id int, amount decimal (18,2) ); go INSERT INTO Buy_Table (user_id, amount) VALUES ('1', 10), ('1', 8), ('1', 20), ('3', 1), ('2', 2); go CREATE TABLE Sell_Table ( sell_id int identity primary key, user_id int, amount decimal (18,2) ); go INSERT INTO Sell_Table (user_id, amount) VALUES ('1', 10), ('1', 8), ('1', 20), ('3', 3), ('2', 3); go select [user_id], 'Buy' as [Type], buy_id as [ID], amount from Buy_Table union all select [user_id], 'Sell', sell_id, amount from Sell_Table order by [user_id], [ID], [Type] However the above query will return each row of the user_id like this I want to display my result to something like this in a grid: Can this be done in query itself rather manipulating the grid? Thx

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• MemoryStream, XmlTextWriter and Warning 4 CA2202 : Microsoft.Usage

  - by rasx

  The Run Code Analysis command in Visual Studio 2010 Ultimate returns a warning when seeing a certain pattern with MemoryStream and XmlTextWriter. This is the warning: Warning 7 CA2202 : Microsoft.Usage : Object 'ms' can be disposed more than once in method 'KinteWritePages.GetXPathDocument(DbConnection)'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object.: Lines: 421 C:\Visual Studio 2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 421 Songhay.DataAccess.KinteWritePages This is the form: static XPathDocument GetXPathDocument(DbConnection connection) { XPathDocument xpDoc = null; var ms = new MemoryStream(); try { using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8)) { using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql)) { writer.WriteStartDocument(); writer.WriteStartElement("data"); do { while(reader.Read()) { writer.WriteStartElement("item"); for(int i = 0; i < reader.FieldCount; i++) { writer.WriteRaw(String.Format("<{0}>{1}</{0}>", reader.GetName(i), reader[i].ToString())); } writer.WriteFullEndElement(); } } while(reader.NextResult()); writer.WriteFullEndElement(); writer.WriteEndDocument(); writer.Flush(); ms.Position = 0; xpDoc = new XPathDocument(ms); } } } finally { ms.Dispose(); } return xpDoc; } The same kind of warning is produced for this form: XPathDocument xpDoc = null; using(var ms = new MemoryStream()) { using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8)) { using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql)) { //... } } } return xpDoc; By the way, the following form produces another warning: XPathDocument xpDoc = null; var ms = new MemoryStream(); using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8)) { using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql)) { //... } } return xpDoc; The above produces the warning: Warning 7 CA2000 : Microsoft.Reliability : In method 'KinteWritePages.GetXPathDocument(DbConnection)', object 'ms' is not disposed along all exception paths. Call System.IDisposable.Dispose on object 'ms' before all references to it are out of scope. C:\Visual Studio 2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 383 Songhay.DataAccess.KinteWritePages In addition to the following, what are my options?: Supress warning CA2202. Supress warning CA2000 and hope that Microsoft is disposing of MemoryStream (because Reflector is not showing me the source code). Rewrite my legacy code to recognize the wonderful XDocument and LINQ to XML.

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• Long Running Stored Proc - Report Progress Using BackgroundWorker & Timer

  - by daveywc

  While a long running stored proc (RMR_Seek) is executing (called via a Linq-To-SQL data context) I am trying to call another stored proc (RMR_GetLatestModelMessage) to check a table for the latest status message. The long running stored proc updates the table in question with status messages as it executes. I want to display the status message on a message panel to advise the user of the status of the execution of Proc_A. For various reasons it is not possible to determine how long RMR_Seek will take to execute so a progress bar with percentage increments is not feasible. I thought I'd found the way to do it by calling the long running stored proc from in a BackgroundWorker process DoWork event handler. This worked fine and allowed me to update my message panel with some dummy status messages that were NOT obtained via Proc_B while Proc_A was running. However now that I have tried to implement this fully by calling Proc_B to obtain the status messages I am running into problems that seem to be related to the mix of the backgroundworker and my System.Windows.Forms.Timer. An extract of the code I am using is below. I have tried many different ways around this but each one seems to present its own set of problems. The code below is problematic in the bw_DoWork event. The RMR_Seek stored proc gets called but does not execute properly - it also seems to be inconsistent as to whether _IsCompleted gets set to true. I'm sure there is a better way to achieve what I am trying to do. private bool _IsCompleted; private void RunRevenueSeek() { if (_SelectedModel == null) { MessageBox.Show("Please select a model from the list and try again.", "Model Generation", MessageBoxButtons.OK, MessageBoxIcon.Information); } else { var bw = new BackgroundWorker(); bw.DoWork += new DoWorkEventHandler(bw_DoWork); ProgressPanelControl.Visible = true; _IsCompleted = false; MessageTimer.Start(); // Has an interval of 3000 bw.RunWorkerAsync(); ProgressLabelControl.Text = "Refreshing Data"; this.Update(); ...more code goes here } } private void bw_DoWork(object sender, DoWorkEventArgs e) { using (var dc = new RevMdlrDataClassesDataContext()) { dc.CommandTimeout = 300; dc.RMR_Seek(_SelectedModel.ModelSet_ID); _IsCompleted = true; } } private void MessageTimer_Tick(object sender, EventArgs e) { string message = ""; if (_IsCompleted) { MessageTimer.Stop(); } else { using (var dc = new RevMdlrDataClassesDataContext()) { dc.CommandTimeout = 300; dc.RMR_GetLatestModelMessage(_SelectedModel.ModelSet_ID, ref message); ProgressLabelControl.Text = message; this.Update(); } } }

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• linq groupby in strongly typed MVC View

  - by jason

  How do i get an IGrouping result to map to the view? I have this query: var groupedManuals = manuals.GroupBy(c => c.Series); return View(groupedManuals); What is the proper mapping for the ViewPage declaration? Inherits="System.Web.Mvc.ViewPage<IEnumerable<ProductManual>>"

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• System.MissingMemberException was unhandled by user code

  - by AmRoSH

  I'm using this code: Dim VehiclesTable1 = dsVehicleList.Tables(0) Dim VT1 = (From d In VehiclesTable1.AsEnumerable _ Select VehicleTypeName = d.Item("VehicleTypeName") _ , VTypeID = d.Item("VTypeID") _ , ImageURL = d.Item("ImageURL") _ , DailyRate = d.Item("DailyRate") _ , RateID = d.Item("RateID")).Distinct its linq to dataset and I Take Data on THis Rotator: <telerik:RadRotator ID="RadRotatorVehicleType" runat="server" Width="620px" Height="145" ItemWidth="155" ItemHeight="145" ScrollDirection="Left" FrameDuration="1" RotatorType="Buttons"> <ItemTemplate> <div style="text-align: center; cursor: pointer; width: 150px"> <asp:Image ID="ImageVehicleType" runat="server" Width="150" ImageUrl='<%# Container.DataItem("ImageURL") %>' /> <asp:Label ID="lblVehicleType" runat="server" Text='<%# Container.DataItem("VehicleTypeName") %>' Font-Bold="true"></asp:Label> <br /> <asp:Label ID="lblDailyRate" runat="server" Text='<%# Container.DataItem("DailyRate") %>' Visible="False"></asp:Label> <input id="HiddenVehicleTypeID" type="hidden" value='<%# Container.DataItem("VTypeID") %>' name="HiddenVehicleTypeID" runat="server" /> <input id="HiddenRateID" type="hidden" value='<%# Container.DataItem("RateID") %>' name="HiddenRateID" runat="server" /> </div> </ItemTemplate> <ControlButtons LeftButtonID="img_left" RightButtonID="img_right" /> </telerik:RadRotator> and I got this Exception: No default member found for type 'VB$AnonymousType_0(Of Object,Object,Object,Object,Object)'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.MissingMemberException: No default member found for type 'VB$AnonymousType_0(Of Object,Object,Object,Object,Object)'. I don't know whats up ? Any help please. Thanks for who tried to solve this but I got solution: using '<%# DataBinder.Eval(Container.DataItem,"ImageURL") %>' instead of '<%# Container.DataItem("RateID") %>' Thanks,

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• Problem updating through LINQtoSQL in MVC application using StructureMap, Repository Pattern and UoW

  - by matt

  I have an ASP MVC application using LINQ to SQL for data access. I am trying to use the Repository and Unit of Work patterns, with a service layer consuming the repositories and unit of work. I am experiencing a problem when attempting to perform updates on a particular repository. My application architecture is as follows: My service class: public class MyService { private IRepositoryA _RepositoryA; private IRepositoryB _RepositoryB; private IUnitOfWork _unitOfWork; public MyService(IRepositoryA ARepositoryA, IRepositoryB ARepositoryB, IUnitOfWork AUnitOfWork) { _unitOfWork = AUnitOfWork; _RepositoryA = ARepositoryA; _RepositoryB = ARepositoryB; } public PerformActionOnObject(Guid AID) { MyObject obj = _RepositoryA.GetRecords() .WithID(AID); obj.SomeProperty = "Changed to new value"; _RepositoryA.UpdateRecord(obj); _unitOfWork.Save(); } } Repository interface: public interface IRepositoryA { IQueryable<MyObject> GetRecords(); UpdateRecord(MyObject obj); } Repository LINQtoSQL implementation: public class LINQtoSQLRepositoryA : IRepositoryA { private MyDataContext _DBContext; public LINQtoSQLRepositoryA(IUnitOfWork AUnitOfWork) { _DBConext = AUnitOfWork as MyDataContext; } public IQueryable<MyObject> GetRecords() { return from records in _DBContext.MyTable select new MyObject { ID = records.ID, SomeProperty = records.SomeProperty } } public bool UpdateRecord(MyObject AObj) { MyTableRecord record = (from u in _DB.MyTable where u.ID == AObj.ID select u).SingleOrDefault(); if (record == null) { return false; } record.SomeProperty = AObj.SomePropery; return true; } } Unit of work interface: public interface IUnitOfWork { void Save(); } Unit of work implemented in data context extension. public partial class MyDataContext : DataContext, IUnitOfWork { public void Save() { SubmitChanges(); } } StructureMap registry: public class DataServiceRegistry : Registry { public DataServiceRegistry() { // Unit of work For<IUnitOfWork>() .HttpContextScoped() .TheDefault.Is.ConstructedBy(() => new MyDataContext()); // RepositoryA For<IRepositoryA>() .Singleton() .Use<LINQtoSQLRepositoryA>(); // RepositoryB For<IRepositoryB>() .Singleton() .Use<LINQtoSQLRepositoryB>(); } } My problem is that when I call PerformActionOnObject on my service object, the update never fires any SQL. I think this is because the datacontext in the UnitofWork object is different to the one in RepositoryA where the data is changed. So when the service calls Save() on it's IUnitOfWork, the underlying datacontext does not have any updated data so no update SQL is fired. Is there something I've done wrong in the StrutureMap registry setup? Or is there a more fundamental problem with the design? Many thanks.

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• How to created filtered reports in WPF?

  - by Michael Goyote

  Creating reports in WPF. I have two related tables. Table A-Customer: CustomerID(PK) Names Phone Number Customer Num Table B-Items: Products Price CustomerID I want to be able to generate a report like this: CustomerA Items Price Item A 10 Item B 10 Item C 10 --------------- Total 30 So this is what I have done: <Window x:Class="ReportViewerWPF.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:rv="clr-namespace:Microsoft.Reporting.WinForms; assembly=Microsoft.ReportViewer.WinForms" Title="Customer Report" Height="300" Width="400"> <Grid> <WindowsFormsHost Name="windowsFormsHost1"> <rv:ReportViewer x:Name="reportViewer1"/> </WindowsFormsHost> </Grid> Then I created a dataset and loaded the two tables, followed by a report wizard (dragged all the available fields and dropped them to the Values pane). The code behind the WPF window is this: public partial class CustomerReport : Window { public CustomerReport() { InitializeComponent(); _reportViewer.Load += ReportViewer_Load; } private bool _isReportViewerLoaded; private void ReportViewer_Load(object sender, EventArgs e) { if (!_isReportViewerLoaded) { Microsoft.Reporting.WinForms.ReportDataSource reportDataSource1 = new Microsoft.Reporting.WinForms.ReportDataSource(); HM2DataSet dataset = new HM2DataSet(); dataset.BeginInit(); reportDataSource1.Name = "DataSet";//This is the dataset name reportDataSource1.Value = dataset.CustomerTable; this.reportViewer1.LocalReport.DataSources.Add(reportDataSource1); this.reportViewer1.LocalReport.ReportPath = "../../Report3.rdlc"; dataset.EndInit(); HM2DataSetTableAdapters.CustomerTableAdapter funcTableAdapter = new HM2DataSetTableAdapters.CustomerTableAdapter(); funcTableAdapter.ClearBeforeFill = true; funcTableAdapter.Fill(dataset.CustomerTable); _reportViewer.RefreshReport(); _isReportViewerLoaded = true; } } As you might have guessed this loaded this list of customer with items and price: Customer Items Price Customer A Items A 10 Customer A Items B 10 Customer B Items D 10 Customer B Items C 10 How can I fine-tune this report to look like the one above, where the user can filter the customer he wants displayed on the report? Thanks in advance for the help. I would have preferred to use LINQ whenever filtering data

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• How to get record value from LinqDataSource via Code Behind

  - by rockinthesixstring

  I've got a LinqDataSource that retrieves a single record. Protected Sub LinqDataSource1_Selecting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.LinqDataSourceSelectEventArgs) Handles LinqDataSource1.Selecting Dim BizForSaleDC As New DAL.BizForSaleDataContext e.Result = BizForSaleDC.bt_BizForSale_GetByID(e.WhereParameters("ID")).FirstOrDefault End Sub I'd like to be able to retrieve the values of said DataSource using the Page_Load function. Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load 'Get the right usercontrol' Dim ctrl As UserControl Select Case DataBinder.Eval(LINQDATASOURCE_SOMETHING.DataItem, "AdType") Case 1 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 2 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 3 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case 4 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case Else : ctrl = Nothing End Select 'set the control to visible' ctrl.Visible = True End Sub But obviously the code above doesn't work... I'm just wondering if there's a way to make it work. Here is the full markup <body> <form id="form1" runat="server"> <asp:LinqDataSource ID="LinqDataSource1" runat="server"> <WhereParameters> <asp:QueryStringParameter ConvertEmptyStringToNull="true" Name="ID" QueryStringField="ID" Type="Int32" /> </WhereParameters> </asp:LinqDataSource> <uc:Default ID="Default1" runat="server" Visible="false" /> <uc:ValuPro ID="ValuPro1" runat="server" Visible="false" /> </form> </body> </html> Basically what happens is the appropriate usercontrol is enabled and that usercontrol inherits the LinqDataSource and displays the appropriate information. EDIT: It's working now with the code below, however, since I'm really not into hitting the database multiple times for the same info, I'd prefer to get the value from the DataSource. 'Query the database' Dim _ID As Integer = Convert.ToInt32(Request.QueryString("ID")) Dim BizForSaleDC As New BizForSaleDataContext Dim results = BizForSaleDC.bt_BizForSale_GetByID(_ID).FirstOrDefault 'Get the right usercontrol' Dim ctrl As UserControl Select Case results.AdType Case 1 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 2 : ctrl = DirectCast(Me.FindControl("Default1"), UserControl) Case 3 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case 4 : ctrl = DirectCast(Me.FindControl("ValuPro1"), UserControl) Case Else : ctrl = Nothing End Select

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• Django ORM: Ordering w/ aggregate functions — None special treatment

  - by deno

  Hi, I'm doing query like that: SomeObject.objects.annotate(something=Avg('something')).order_by(something).all() Now, I normally have an aggregate field in my model that I use with Django signals to keep in sync, however in this case perfomance isn't an issue so I thought I'd keep it simple and just use subqueries. This approach, however, presented an unexpected issue: It all works grate if aggregate function results are like this: [5.0, 4.0, 6.0 … (etc, just numbers)] However if you mix in some Nones than it's being ordered like this: [None, 5.0, 4.0 …] The issue is that None has higher value than any number, while it should have value at most of 0. I'm using PostgreSQL and haven't tested w/ other DBs. I haven't actually checked what query is generated etc. I worked it around by just sorting in memory: sorted(…, key=lambda _:_.avg_rating if _.avg_rating is not None else 0) So I'm just curious if you know a way to do it w/ just Django ORM. Perhaps .where? or something… Kind regards

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• How do I use a datetime variable with createparameter in classic ASP?

  - by Frank Schmitt

  I'm having a heck of a time trying to create a parameterized query that binds a date variable into a stored procedure call: twoyearsago = dateadd("yyyy", -2, date()) DataConn.ConnectionString = myConnectionString DataConn.Open Set rs = Server.CreateObject("ADODB.Recordset") Set DataCmd = Server.CreateObject("ADODB.Command") DataCmd.ActiveConnection = DataConn DataCmd.CommandText = "exec myStoredProc ?, ?" DataCmd.Parameters.Append DataCmd.CreateParameter("@start", adDate, , 10, date()) DataCmd.Parameters.Append DataCmd.CreateParameter("@end", adDate, , 10, twoyearsago) rs.Open DataCmd The stored proc returns nothing (indicating the dates aren't making it through). If I hard code dates in the query, e.g.: DataCmd.CommandText = "exec myStoredProc '01/01/2008', '01/01/2010'" I get the results I would expect. Calling CStr on my dates (if that makes a difference) returns them in the above format.

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• django select max field from mysql when column is varchar

  - by doza

  Hi, Using Django 1.1, I am trying to select the maximum value from a varchar column (in MySQL.) The data stored in the column looks like: 9001 9002 9017 9624 10104 11823 (In reality, the numbers are much bigger than this.) This worked until the numbers incremented above 10000: Feedback.objects.filter(est__pk=est_id).aggregate(sid=Max('sid')) Now, that same line would return 9624 instead of 11823. I'm able to run a query directly in the DB that gives me what I need, but I can't figure out the best way to do this in Django. The query would be: select max(sid+0) from Feedback; Any help would be much appreciated. Thanks!

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• Can't get SubSonic insert to work

  - by Darkwater23

  I'm trying to insert a record into a table without using the SubSonic object in a VB.Net Windows app. (It will take too long to explain why.) Dim q As New SubSonic.Query("tablename") q.QueryType = SubSonic.QueryType.Insert q.AddUpdateSetting("Description", txtDescription.Text) q.Execute() This just updates all the rows in the table. I read in one post that instead of AddUpdateSetting, I should use AddWhere, but that didn't make any sense to me. I don't need a where clause at all. Searching for all:QueryType.Insert at subsonicproject.com didn't return anything (which I thought was weird). Can anyone tell me how to fix this query? Thanks!

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• MDX Except function in where clause

  - by rfders

  Hi, i'm having problem restricting a query in mdx, using except function at where clause. i need to retrieved a set of data but which not in an specific set. Then i created the next query: select {[Measures].[Amount], [Measures].[Transaction Cost], [Measures].[Transaction Number]} ON COLUMNS,{[ManualProcessing].[All ManualProcessings].[MAGNETICSTRIPE], ManualProcessing].[All ManualProcessings].[MANUAL]} ON ROWS FROM [Transactions] where except([Product].[All Products].Children,{[Product].[All Products].[Debit}) apparently this works fine, but when i try to add another restriction to slicer, i got this error: No function matches signature (Set,Member). I'm currently working on mondrian 3.1 Is it possible to add multiple restriction to slicer when im sing the except funtion ? are there any other way to get this ? thanks in advance.

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• Blogger (Python) API: How do I retrieve a post by post ID?

  - by larsks

  Having previously obtained a post ID from a call to gdata.blogger.client.add_post()... post = client.add_post(...) post_id = post.get_post_id() ...how do I use that post id to retrieve the post in the future? I thought maybe gdata.blogger.client.Query would be the way to go, but this doesn't support post id as a query term. The example code distributed with the Python gdata module doesn't have an example of this use case, and after poking around gdata.blogger.client.* for a while I'm not making much progress. I could obviously iterate through all the posts in the blog until find the one with the corresponding id, but that would be a terrible, terrible idea.

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• Adjusting sql statement in a function based upon input

  - by Stefan

  Hey there, This is a bit urgent! I'm trying to make a simple filter search where-by you can choose from a series of 3 drop downs and then based upon this the results are then displayed, How would I go about adjusting the sql query for each and if you were to only choose to search from aone of the 3 rather than all 3 etc... example there could be the url with input such as: url.com?location=gb&color=3&hair=4 and still form the correct sql query for something like this: url.com?location=gb&hair=1 and not encounter problems with WHERE and AND etc etc and empty variables in the statement Would this not need to be a massive function to check using if to see how the data is set for all possibilities? Thanks, Stefan

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• Should i really use integer primary IDs?

  - by arthurprs

  For example, i always generate an auto-increment field for the users table, but i also specifies an UNIQUE index on their usernames. There is situations that i first need to get the userId for a given username and then execute the desired query. Or use a JOIN in the desired query. It's 2 trips to the database or a JOIN vs. a varchar index The above is just an example There is a real performance benefit on INT over small VARCHAR indexes? Thanks in advance!

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• iPhone SDK / Core Data usage scenario, similar to GAE data store?

  - by boliva

  Hi all, I am currently rewriting a map based App which I wrote in the past, specifically for 2.2.1 devices. Originally I wrote it to make use of SQLite databases but I would like to try and migrate it over Core Data, now that it's available on 3.X (for which I am rewriting to). I am fairly experienced in iPhone/Obj-C development, SQL and server backend technologies, but I have never had the chance to work with Core Data so IDK really if it's the appropiate tool for what I am trying to accomplish. The App works on a limited area in a map over which there are about 4000 placemarks, with different kinds of icons and sizes. Of course not all 4000 placemarks are shown at once but only those currently visible in the map viewport, and depending on the zoom level. What I am doing right now is, after the user moves the map in any way (panning or zooming) I am requesting from the backend server the required information for the placemarks that would be visible given the viewport coordinates boundaries and zoom level, however the process isn't as smooth as I'd like (the backend is sending its response in XML and I am compressing it using gzip), it takes anywhere from 1 to 3 seconds to update the display of the placemarks after the user ends moving the map. What I would like to do is to prefetch all the placemarks data at the App launch and use it all through the app life time - I don't mind storing it for later use because the data should be dynamic. The way I would do it right now is, after retrieving all the data, to store it on an SQLite db which I would query later, whenever the user moves the map, to return only the placemarks inside the viewport coordinate boundaries and specific to a given zoom level. Now, the question itself is, if is it possible to use some more 'native', object driven way to carry this queries process, which got me thinking about Core Data and if it is in any way similar to what Google App Engine offers through its datastore where you can fetch a number of objects from the backend given a certain query or criteria, without resorting to an SQL query itself. Like I said before I don't have any experience on Core Data but I have a pretty deep understanding of Obj-C and iPhone development, as well as SQL databases. Any guides on how to achieve what I'm trying (if possible at all) would be greatly appreciated.

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• Ordering by top commented.

  - by MILESMIBALERR

  How would I list a page of the top commented pages on the site with PHP and mysql. The database is set up sort of like this: page_id | username | comment | date_submitted page 1-------bob-------hello-----current date page 1-------joe-------byebye-----current date page 4-------joe--------stuff-------date page 3-------mark--------this--------a date how would you query it so that it orders them by top commented pages? here is a simple query to start with: $querycomments = sprintf("SELECT * FROM comments WHERE !!!!!HELLLLLP HERRE!!!!! = %s ORDER BY !!!!!!HELLLP HERE!!!!!! DESC", GetSQLValueString(????????????, "text"));

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• I need to calculate the date / time difference between one date time column

  - by Stringz

  Details. I have the notes table having the following columns. ID - INT(3) Date - DateTime Note - VARCHAR(100) Tile - Varchar(100) UserName - Varchar(100) Now this table will be having NOTES along with the Titles entered by UserName on the specified date / time. I need to calculate the DateTimeDifference between the TWO ROWS in the SAME COLUMN For example the above table has this peice of information in the table. 64, '2010-03-26 18:16:13', 'Action History', 'sending to Level 2.', 'Salman Khwaja' 65, '2010-03-26 18:19:48', 'Assigned By', 'This is note one for the assignment of RF.', 'Salman Khwaja' 66, '2010-03-27 19:19:48', 'Assigned By', 'This is note one for the assignment of CRF.', 'Salman Khwaja' Now I need to have the following resultset in query reports using MYSQL. TASK - TIME Taken ACTION History - 2010-03-26 18:16:13 Assigned By - 00:03:35 Assigned By - 25:00:00 More smarter approach would be TASK - TIME Taken ACTION History - 2010-03-26 18:16:13 Assigned By - 3 minutes 35 seconds Assigned By - 1 day, 1 hour. I would appreciate if one could give me the PLAIN QUERY along with PHP code to embed it too.

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• select only new row in oracle

  - by Hlex

  Hi, I have table with "varchar2" as primary key. Transaction is about 1 000 000 per day. my app wake up every 5 minute to generate text file by query only new record. It will remember last point and do only new record. 1)Do you have idea how query with good performance? I able to add new column if need. 2)what do you think this process should do by? plsql? java?

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• How to cache queries in Rails across multiple requests

  - by m.u.sheikh

  I want to cache query results so that the same results are fetched "for more than one request" till i invalidate the cache. For instance, I want to render a sidebar which has all the pages of a book, much like the index of a book. As i want to show it on every page of the book, I have to load it on every request. I can cache the rendered sidebar index using action caching, but i also want to actually cache the the query results which are used to generate the html for the sidebar. Does Rails provide a way to do it? How can i do it?

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• Adjust SQL query to DB2

  - by Guy Roth

  Part of a complex query that our app is running contains the lines: ...(inner query) SELECT ... NULL as column_A, NULL as column_B, ... FROM ... This syntax of creating columns with null values is not allowed in DB2 altough it is totally OK in MSSQL and Oracle DBs. Technically I can change it to: '' as column_A, '' as column_B, But this doesn't have exactly the same meaning and can damage our calculation results. How can I create columns with null values in DB2 using other syntax??

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