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  • C# Help with a basic pedagogic example of a BackGroundWorker process populating a DataGridView

    - by Roger
    Scenario: I have a windows form that holds a DataGridWiew with 3 pre-defined columns. I have 3 variables declared outside the function and assigned to inside the function. I have a function that enumerates stuff and puts it in the 3 columns, line by line: string VARIABLE1; string VARIABLE2; string VARIABLE3; private void FunctionEnumerateStuff() { foreach (StuffObject STUFF in StuffCollection) { VARIABLE1 = STUFF.SubStuff1.ToString(); VARIABLE2 = STUFF.SubStuff2.ToString(); VARIABLE3 = STUFF.SubStuff3.ToString(); DatagridWiew1.Rows.Add(VALUE1, VALUE2, VALUE3); } } What I want to do, is to execute this function from a BackGroundWorker process, so that the GUI of the application will be smooth and responsive. I have read up on backgroundworkers but I am having trouble relating, because all examples seems to be of entirely different scenarios and most of them are overwelmingly complex. San some helpful pedagogic soul help me and others with a very basic example of how to get this to work in the simplest way possible. Thanks.

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  • Getting minimum - Min() - for DateTime column in a DataTable using LINQ to DataSets?

    - by Jay Stevens
    I need to get the minimum DateTime value of a column in a DataTable. The DataTable is generated dynamically from a CSV file, therefore I don't know the name of that column until runtime. Here is code I've got that doesn't work... private DateTime GetStartDateFromCSV(string inputFile, string date_attr) { EnumerableRowCollection<DataRow> table = CsvStreamReader.GetDataTableFromCSV(inputFile, "input", true).AsEnumerable(); DateTime dt = table.Select(record => record.Field<DateTime>(date_attr)).Min(); return dt; } The variable table is broken out just for clarity. I basically need to find the minimum value as a DateTime for one of the columns (to be chosen at runtime and represented by date_attr). I have tried several solutions from SO (most deal with known columns and/or non-DateTime fields). What I've got throws an error at runtime telling me that it can't do the DateTime conversion (that seems to be a problem with Linq?) I've confirmed that the data for the column name that is in the string date_attr is a date value.

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  • Sorting Arrays by More the One Value, and Prioritizing the Sort based on Column data.

    - by Mark Tomlin
    I'm looking for a way to sort an array (we call this a row), with an array of values (that I'll call columns). Each row has columns that must be sorted based on the priority of: timetime, lapcount & timestamp. Each column cotains this information: split1, split2, split3, laptime, lapcount, timestamp. laptime if in hundredths of a second. (1:23.45 or 1 Minute, 23 Seconds & 45 Hundredths is 8345.) Lapcount is a simple unsigned tiny int, or unsigned char. timestamp is unix epoch. The lowest laptime should be at the get a better standing in this sort. Should two peoples laptimes equal, then timestamp will be used to give the better standing in this sort. Should two peoples timestamp equal, then the person with less of a lapcount get's the better standing in this sort. By better standing, I mean closer to the top of the array, closer to the index of zero where it a numerical array. I think the array sorting functions built into php can do this with a callback, I was wondering what the best approch was for a weighted sort like this would be.

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  • Sorting Arrays by More the One Value, and Prioritizing the Sort based on Column data.

    - by Mark Tomlin
    I'm looking for a way to sort an array, based on the information in each row, based on the information in certain cells, that I'll call columns. Each row has columns that must be sorted based on the priority of: timetime, lapcount & timestamp. Each column cotains this information: split1, split2, split3, laptime, lapcount, timestamp. laptime if in hundredths of a second. (1:23.45 or 1 Minute, 23 Seconds & 45 Hundredths is 8345.) Lapcount is a simple unsigned tiny int, or unsigned char. timestamp is unix epoch. The lowest laptime should be at the get a better standing in this sort. Should two peoples laptimes equal, then timestamp will be used to give the better standing in this sort. Should two peoples timestamp equal, then the person with less of a lapcount get's the better standing in this sort. By better standing, I mean closer to the top of the array, closer to the index of zero where it a numerical array. I think the array sorting functions built into php can do this with a callback, I was wondering what the best approch was for a weighted sort like this would be.

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  • Optimizing MySQL update query

    - by Jernej Jerin
    This is currently my MySQL UPDATE query, which is called from program written in Java: String query = "UPDATE maxday SET DatePressureREL = (SELECT Date FROM ws3600 WHERE PressureREL = (SELECT MAX" + "(PressureREL) FROM ws3600 WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1), " + "PressureREL = (SELECT PressureREL FROM ws3600 WHERE PressureREL = (SELECT MAX(PressureREL) FROM ws3600 " + "WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1), ..."; try { s.execute(query); } catch (SQLException e) { System.out.println("SQL error"); } catch(Exception e) { e.printStackTrace(); } Let me explain first, what does it do. I have two tables, first is ws3600, which holds columns (Date, PressureREL, TemperatureOUT, Dewpoint, ...). Then I have second table, called maxday, which holds columns like DatePressureREL, PressureREL, DateTemperatureOUT, TemperatureOUT,... Now as you can see from an example, I update each column, the question is, is there a faster way? I am asking this, because I am calling MAX twice, first to find the Date for that value and secondly to find the actual value. Now I know that I could write like that: SELECT Date, PressureREL FROM ws3600 WHERE PressureREL = (SELECT MAX(PressureREL) FROM ws3600 WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1 That way I get the Date of the max and the max value at the same time and then update with those values the data in maxday table. But the problem of this solution is, that I have to execute many queries, which as I understand takes alot more time compared to executing one long mysql query because of overhead in sending each query to the server. If there is no better way, which solution beetwen this two should I choose. The first, which only takes one query but is very unoptimized or the second which is beter in terms of optimization, but needs alot more queries which probably means that the preformance gain is lost because of overhead in sending each query to the server?

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  • Is it possible to update old database from dbml file ? (C#, .Net 4, Linq, SQL Server)

    - by Emil
    Hi all, I began recently a new job, a very interesting project (C#,.Net 4, Linq, VS 2010 and SQL Server). And immediately I got a very exciting challenge: I must implement either a new tool or integrate the logic when program start, or whatever, but what must happen is the following: the customers have previous application and database (full with their specific data). Now a new version is ready and the customer gets the update. In the mean time we made some modification on DB (new table, columns, maybe an old column deleted, or whatever). I’m pretty new in Linq and also SQL databases and my first solution can be: I check the applications/databases version and implement all the changes step by step comparing all tables, columns, keys, constrains, etc. (all this new information I have in my dbml and the old I asked from the existing DB). And I’ll do this each time the version changed. But somehow I feel, this is NOT a smart solution so I look for a general solution of this problem. Is there a way to update customers DB from the dbml file? To create a new one is not a problem (CreateDatabase with DataContext), is there any update/alter database methods? I guess I’m not the only one who search for such a solution (I found nothing in internet – or I looked for bad keywords). How did you solve this problem? I look also for an external tool, but first for a solution with C#, Linq or something similar. For any idea thank you in advance! Best regards, Emil

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  • How to make a hyperlink through GridView column value?

    - by avirk
    I want here that user can see the answer under the question by selecting its heading. The question should be a hyperlink to redirect me on the page Answer.aspx. I mean to say that when user take cursor over the How to do this? it should redirect the user to the desired page. How can I do that? here is the code <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDataSource1" Width="100%" BorderStyle="None"> <Columns> <asp:BoundField DataField="QuestionHEAD" HeaderText="Question" SortExpression="QuestionHEAD" HeaderStyle-ForeColor="white" HeaderStyle-BackColor="Brown"/> <asp:BoundField DataField="Problem" HeaderText="Problem" SortExpression="Problem" HeaderStyle-ForeColor="white" HeaderStyle-BackColor="Brown" /> <asp:BoundField DataField="Forum" HeaderText="Forum" SortExpression="Forum" HeaderStyle-ForeColor="white" HeaderStyle-BackColor="Brown"/> <asp:BoundField DataField="Username" HeaderText="Asked By" SortExpression="Username" HeaderStyle-ForeColor="white" HeaderStyle-BackColor="Brown" /> </Columns> </asp:GridView> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:connectionstring %>" SelectCommand="SELECT [QuestionHEAD], [Problem], [Forum], [Username] FROM [Question]"> </asp:SqlDataSource>

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  • Syntax Error in MySql StoredProc

    - by karthik
    I am using the below stored proc in mysql to generate the insert statements. I am getting the following error : Script line: 4 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '\’”\’,',’ifnull(‘,column_name,’,””)’,',\’”\’)')) INTO @S' at line 12 What would be the syntax problem in that ? DELIMITER $$ DROP PROCEDURE IF EXISTS `InsGen` $$ CREATE DEFINER=`root`@`localhost` PROCEDURE `InsGen`(in_db varchar(20),in_table varchar(20),in_file varchar(100)) BEGIN declare Whrs varchar(500); declare Sels varchar(500); declare Inserts varchar(2000); declare tablename varchar(20); set tablename=in_table; select tablename; # Comma separated column names – used for Select select group_concat(concat(‘concat(\’”\’,',’ifnull(‘,column_name,’,””)’,',\’”\’)')) INTO @Sels from information_schema.columns where table_schema=’test’ and table_name=tablename; # Comma separated column names – used for Group By select group_concat(‘`’,column_name,’`') INTO @Whrs from information_schema.columns where table_schema=’test’ and table_name=tablename; #Main Select Statement for fetching comma separated table values set @Inserts=concat(“select concat(‘insert into “, in_db,”.”,tablename,” values(‘,concat_ws(‘,’,”,@Sels,”),’);’) from “, in_db,”.”,tablename,” group by “,@Whrs, ” INTO OUTFILE ‘”, in_file ,”‘”); PREPARE Inserts FROM @Inserts; EXECUTE Inserts; END $$ DELIMITER ;

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  • Automatic multi-page multi-column flowing text with QtWebkit (HTML/CSS/JS -> PDF)

    - by Peter Boughton
    I have some HTML documents that are converted to PDF, using software that renders using QtWebkit (not sure which version). Currently, the documents have specific tags to split into columns and pages - so whenever the wording changes, it is a manual time-consuming process to move these tags so that the columns and pages fit. Can anyone provide a way to have text auto-wrapped into the next column/page (as appropriate) when it reaches the bottom of the current container? Any HTML, CSS or JS supported by QtWebkit is ok (assuming it works in the PDF converter). (I have tested the webkit-column-* in CSS3 and it appears QtWebkit does not support this.) To make things more exciting, it also needs to: - put a header at the top of each page, with page X of Y numbering; - if an odd number of pages, add a blank page at the end (with no header); - have the ability to say "don't break inside this block" or "don't break after this header" I have put some quick example initial markup and target markup to help explain what I'm trying to do. (The actual documents are far more complicated than that, but I need a simple proof-of-concept before I attack the real ones.) Any suggestions? Update: I've got a partially working solution using Aaron's "filling up" suggestion - I'll post more details in a bit.

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  • MySQL MyISAM table performance... painfully, painfully slow

    - by Salman A
    I've got a table structure that can be summarized as follows: pagegroup * pagegroupid * name has 3600 rows page * pageid * pagegroupid * data references pagegroup; has 10000 rows; can have anything between 1-700 rows per pagegroup; the data column is of type mediumtext and the column contains 100k - 200kbytes data per row userdata * userdataid * pageid * column1 * column2 * column9 references page; has about 300,000 rows; can have about 1-50 rows per page The above structure is pretty straight forwad, the problem is that that a join from userdata to page group is terribly, terribly slow even though I have indexed all columns that should be indexed. The time needed to run a query for such a join (userdata inner_join page inner_join pagegroup) exceeds 3 minutes. This is terribly slow considering the fact that I am not selecting the data column at all. Example of the query that takes too long: SELECT userdata.column1, pagegroup.name FROM userdata INNER JOIN page USING( pageid ) INNER JOIN pagegroup USING( pagegroupid ) Please help by explaining why does it take so long and what can i do to make it faster. Edit #1 Explain returns following gibberish: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE userdata ALL pageid 372420 1 SIMPLE page eq_ref PRIMARY,pagegroupid PRIMARY 4 topsecret.userdata.pageid 1 1 SIMPLE pagegroup eq_ref PRIMARY PRIMARY 4 topsecret.page.pagegroupid 1 Edit #2 SELECT u.field2, p.pageid FROM userdata u INNER JOIN page p ON u.pageid = p.pageid; /* 0.07 sec execution, 6.05 sec fecth */ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE u ALL pageid 372420 1 SIMPLE p eq_ref PRIMARY PRIMARY 4 topsecret.u.pageid 1 Using index SELECT p.pageid, g.pagegroupid FROM page p INNER JOIN pagegroup g ON p.pagegroupid = g.pagegroupid; /* 9.37 sec execution, 60.0 sec fetch */ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE g index PRIMARY PRIMARY 4 3646 Using index 1 SIMPLE p ref pagegroupid pagegroupid 5 topsecret.g.pagegroupid 3 Using where Moral of the story Keep medium/long text columns in a separate table if you run into performance problems such as this one.

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  • UDP checksum calculation

    - by Deepak Konidena
    Hi, The UDP header struct defined at /usr/include/netinet/udp.h is as follows struct udphdr { u_int16_t source; u_int16_t dest; u_int16_t len; u_int16_t check; }; What value is stored in the check field of the header? How to verify if the checksum is correct? I meant on what data is the checksum computed? (Is it just the udp header or udp header plus the payload that follows it?) Thanks.

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  • Flex : How to link data to a datagrid ?

    - by Tristan
    Hello, I'm following flex tutorials but i'm not doing exactly as they do, so : What i want I have an input text, with a button 'search'. I want when this button is clicked that the data returned by the function search are displayed in the datagrid. What i have : The text input : <s:TextInput includeIn="DetailServeurs" x="58" y="361" width="209" id="txt_search" text="Default text" focusIn="txt_search_focusInHandler(event)"/> a Search button : <s:Button includeIn="DetailServeurs" x="275" y="361" label="Rechercher" id="btn_rechercher" click="btn_rechercher_clickHandler(event)"/> a clickhandler for this search button : protected function btn_rechercher_clickHandler(event:MouseEvent):void { if(txt_search.text != ""){ getServeurByNameResult.token = serveurService.getServeurByName(txt_search.text); } } and a datagrid : <mx:DataGrid includeIn="DetailServeurs" x="30" y="124" width="1002" height="179" id="dataGrid" dataProvider="{getServeurByNameResult.lastResult}"> <mx:columns> <mx:DataGridColumn headerText="GSP_nom" dataField="GSP_nom"/> <mx:DataGridColumn headerText="port" dataField="port"/> ........ </mx:columns> </mx:DataGrid> So how can i display the results in the datagrid ? Thanks ! ;)

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  • Calling a datatrigger for a radio button inside a datagrid

    - by Farax
    I have a datagrid with one column having a radio button. I want to set the GroupName when a certain condition is reached. Below is the code <Custom:DataGrid.Columns> <!-- ONLY ENABLED WHEN THE ITEM TYPE IS SINGLESELECT OR SINGLESELECT WITH ADDIOTIONAL DATA--> <Custom:DataGridTemplateColumn CanUserResize="False" MinWidth="20" > <Custom:DataGridTemplateColumn.CellTemplate> <DataTemplate> <RadioButton IsChecked="{Binding IsChecked}" d:DesignWidth="16" d:DesignHeight="16" GroupName="SingleChoiceSelection" Template="{DynamicResource RadioButtonTemplate}" Background="{DynamicResource BackgroundNew}" BorderBrush="#FF7A7171" Foreground="#FF6C6C6C" Margin="0" /> </DataTemplate> </Custom:DataGridTemplateColumn.CellTemplate> </Custom:DataGridTemplateColumn> <Custom:DataGridTextColumn Header="Choices" Binding="{Binding ChoiceText}" CellStyle="{DynamicResource DataGridCellStyle2}" MinWidth="150" /> </Custom:DataGrid.Columns> </Custom:DataGrid> The ItemSource contains a property called isChecked and I want to change the foreground color when isChecked is changed to true. How do i do this with a datatrigger?

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  • Why is there a limit of max 20 parameters to a clojure function

    - by GuyC
    Hi, there seems to be a limit to the number of parameters a clojure function can take. When defining a function with more than 20 parameters I receive the following: Obviously this can be avoided, but I was hitting this limit porting the execution model of an existing DSL to clojure, and I have constructs in my DSL like the following, which by macro expansion can be mapped to functions quite easily except for this limit: (defAlias nn1 ((element ?e1) (element ?e2)) number "@doc features of the elements are calculated for entry into the first neural network, the result is the score computed by the latter" (nn1-recall (nn1-feature00 ?e1 ?e2) (nn1-feature01 ?e1 ?e2) ... (nn1-feature89 ?e1 ?e2))) which is a DSL statement to call a neural network with 90 input nodes. Can work around it of course, but was wondering where the limit comes from. Thanks.

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  • How to improve performance of non-scalar aggregations on denormalized tables

    - by The Lazy DBA
    Suppose we have a denormalized table with about 80 columns, and grows at the rate of ~10 million rows (about 5GB) per month. We currently have 3 1/2 years of data (~400M rows, ~200GB). We create a clustered index to best suit retrieving data from the table on the following columns that serve as our primary key... [FileDate] ASC, [Region] ASC, [KeyValue1] ASC, [KeyValue2] ASC ... because when we query the table, we always have the entire primary key. So these queries always result in clustered index seeks and are therefore very fast, and fragmentation is kept to a minimum. However, we do have a situation where we want to get the most recent FileDate for every Region, typically for reports, i.e. SELECT [Region] , MAX([FileDate]) AS [FileDate] FROM HugeTable GROUP BY [Region] The "best" solution I can come up to this is to create a non-clustered index on Region. Although it means an additional insert on the table during loads, the hit isn't minimal (we load 4 times per day, so fewer than 100,000 additional index inserts per load). Since the table is also partitioned by FileDate, results to our query come back quickly enough (200ms or so), and that result set is cached until the next load. However I'm guessing that someone with more data warehousing experience might have a solution that's more optimal, as this, for some reason, doesn't "feel right".

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  • Rails paginate array items one-by-one instead of page-by-page

    - by hnovick
    Hi Guys, I have a group of assets, let's call them "practitioners". I'm displaying these practitioners in the header of a calendar interface. There are 7 columns to the calendar. 7 columns = 7 practitioners per view/page. Right now: if the first page shows you practitioners 1-7, when you go the next page you will see practitioners 8-15, next page 16-23, etc. etc. i am wondering how to page the practitioners so that if the first page shows you practitioners 1-7, the next page will show you practitioners 2-8, then 3-9, etc. etc. i would greatly appreciate any help you can offer. here is the rails code i am working with. best regards, harris novick # get the default sort order sort_order = RESOURCE_SORT_ORDER # if we've been given asset ids, start our list with them unless params[:asset_ids].blank? params[:asset_ids] = params[:asset_ids].values unless params[:asset_ids].is_a?(Array) sort_order = "#{params[:asset_ids].collect{|id| "service_provider_resources.id = #{id} DESC"}.join(",")}, #{sort_order}" end @asset_set = @provider.active_resources(:include => {:active_services => :latest_approved_version}).paginate( :per_page => RESOURCES_IN_DAY_VIEW, :page => params[:page], :order => sort_order )

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  • SQL Joins Excluding Data

    - by Andrew
    Say I have three tables: Fruit (Table 1) ------ Apple Orange Pear Banana Produce Store A (Table 2 - 2 columns: Fruit for sale => Price) ------------------------- Apple => 1.00 Orange => 1.50 Pear => 2.00 Produce Store B (Table 3 - 2 columns: Fruit for sale => Price) ------------------------ Apple => 1.10 Pear => 2.50 Banana => 1.00 If I would like to write a query with Column 1: the set of fruit offered at Produce Store A UNION Produce Store B, Column 2: Price of the fruit at Produce Store A (or null if that fruit is not offered), Column 3: Price of the fruit at Produce Store B (or null if that fruit is not offered), how would I go about joining the tables? I am facing a similar problem (with more complex tables), and no matter what I try, if the "fruit" is not at "produce store a" but is at "produce store b", it is excluded (since I am joining produce store a first). I have even written a subquery to generate a full list of fruits, then left join Produce Store A, but it is still eliminating the fruits not offered at A. Any Ideas?

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  • WPF ListView GridView DisplayMemberBinding Center alignin content

    - by Bigginn
    I'm trying to center align data in a ListView/Gridview where I use DisplayMemberBinding. This is (partially) how my gridview looks: <ListView> <ListView.View> <GridView> <GridView.Columns> <GridViewColumn DisplayMemberBinding="{Binding Path=Timi}" Width="Auto"> <GridViewColumnHeader Content="Tími" Click="GridViewColumnHeader_Click" ></GridViewColumnHeader> </GridViewColumn> </GridView.Columns> </GridView> </ListView.View> </ListView> I tried to use CellTemplate like explained on this page http://msdn.microsoft.com/en-us/library/system.windows.controls.gridviewcolumn.celltemplate.aspx but it didn't work and then later I read somewhere that one should never use cellTemplate and DisplayMemberBinding together. So the question is : How do I center the gridview data when I use DisplayMemberBinding to bind the data to the gridview? Thanks in advance.

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  • Function with missing return value, behavior at runtime

    - by nabulke
    As expected, the compiler (VisualStudio 2008) will give a warning warning C4715: 'doSomethingWith' : not all control paths return a value when compiling the following code: int doSomethingWith(int value) { int returnValue = 3; bool condition = false; if(condition) // returnValue += value; // DOH return returnValue; } int main(int argc, char* argv[]) { int foo = 10; int result = doSomethingWith(foo); return 0; } But the program runs just fine. The return value of function doSomethingWith() is 0. Is is just undefined behavior, or is there a certain rule how the result value is created/computed at runtime. What happens with non-POD datatypes as return value?

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  • How to create column of type password in gridview?

    - by Preeti
    Hi, I am creating an application in which user selects files and provides credentials to open that file. For that i have created three columns in a gridview. User enters password in password column. I want to display '*' in place of characters like we can create a textbox of password type. I have tried this code on 'GridView_CellClick' event : if (GridView.Columns[e.ColumnIndex].HeaderText == "Password") { txtPassword[e.RowIndex] = new TextBox(); txtPassword[e.RowIndex].Name = "txtPassword"+e.RowIndex; txtPassword[e.RowIndex].PasswordChar = '*'; txtPassword[e.RowIndex].Visible = true; txtPassword[e.RowIndex].TextChanged += new if (GridView.CurrentCell.Value == null) txtPassword[e.RowIndex].Text = ""; else txtPassword[e.RowIndex].Text = GridView.CurrentCell.Value.ToString(); txtPassword[e.RowIndex].Location = GridView.GetCellDisplayRectangle(e.ColumnIndex, e.RowIndex + 1, false).Location; txtPassword[e.RowIndex].Size = GridView.GetCellDisplayRectangle(e.ColumnIndex, e.RowIndex + 1, false).Size; txtPassword[e.RowIndex].Visible = true; txtPassword[e.RowIndex].Focus(); } But in above solution characters are displayed. How can i solve this problem???

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  • Why use INCLUDE in a SQL index

    - by StarLite
    I recently encountered an index in a database I maintain that was of the form: CREATE INDEX [IX_Foo] ON [Foo] ( Id ASC ) INCLUDE ( SubId ) In this particular case, the performance problem that I was encountering (a slow SELECT filtering on both Id and SubId) could be fixed by simply moving the SubId column into the index proper rather than as an included column. This got me thinking however that I don't understand the reasoning behind included columns at all, when generally, they could simply be a part of the index itself. Even if I don't particularly care about the items being in the index itself is there any downside to having column in the index rather than simply being included. After some research, I am aware that there are a number of restrictions on what can go into an indexed column (maximum width of the index, and some column types that can't be indexed like 'image'). In these cases I can see that you would be forced to include the column in the index page data. The only thing I can think of is that if there are updates on SubId, the row will not need to be relocated if the column is included (though the value in the index would need to be changed). Is there something else that I'm missing? I'm considering going through the other indexes in the database and shifting included columns in the index proper where possible. Would this be a mistake? I'm primarily interested in MS SQL Server, but information on other DB engines is welcome also.

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  • MYSQL fetch 10 posts, each w/ vote count, sorted by vote count, limited by where clause on posts

    - by nibblebot
    I want to fetch a set of Posts w/ vote count listed, sorted by vote count (e.g.) Post 1 - Post Body blah blah - Votes: 500 Post 2 - Post Body blah blah - Votes: 400 Post 3 - Post Body blah blah - Votes: 300 Post 4 - Post Body blah blah - Votes: 200 I have 2 tables: Posts - columns - id, body, is_hidden Votes - columns - id, post_id, vote_type_id Here is the query I've tried: SELECT p.*, v.yes_count FROM posts p LEFT JOIN (SELECT post_id, vote_type_id, COUNT(1) AS yes_count FROM votes WHERE (vote_type_id = 1) GROUP BY post_id ORDER BY yes_count DESC LIMIT 0, 10) v ON v.post_id = p.id WHERE (p.is_hidden = 0) ORDER BY yes_count DESC LIMIT 0, 10 Correctness: The above query almost works. The subselect is including votes for posts that have is_hidden = 1, so when I left join it to posts, if a hidden post is in the top 10 (ranked by votes), I can end up with records with NULL on the yes_count field. Performance: I have ~50k posts and ~500k votes. On my dev machine, the above query is running in .4sec. I'd like to stay at or below this execution time. Indexes: I have an index on the Votes table that covers the fields: vote_type_id and post_id EXPLAIN id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY p ALL NULL NULL NULL NULL 45985 Using where; Using temporary; Using filesort 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 10 2 DERIVED votes ref VotingPost VotingPost 4 319881 Using where; Using index; Using temporary; Using filesort

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  • What is the proper way to create a recursive entity in the Entity Framework?

    - by Orion Adrian
    I'm currently using VS 2010 RC, and I'm trying to create a model that contains a recursive self-referencing entity. Currently when I import the entity from the model I get an error indicating that the parent property cannot be part of the association because it's set to 'Computed' or 'Identity', though I'm not sure why it does it that way. I've been hand-editing the file to get around that error, but then the model simply doesn't work. What is the proper way to get recursive entities to work in the Entity Framework. CREATE TABLE [dbo].[Appointments]( [AppointmentId] [int] IDENTITY(1,1) NOT NULL, [Description] [nvarchar](1024) NULL, [Start] [datetime] NOT NULL, [End] [datetime] NOT NULL, [Username] [varchar](50) NOT NULL, [RecurrenceRule] [nvarchar](1024) NULL, [RecurrenceState] [varchar](20) NULL, [RecurrenceParentId] [int] NULL, [Annotations] [nvarchar](50) NULL, [Application] [nvarchar](100) NOT NULL, CONSTRAINT [PK_Appointments] PRIMARY KEY CLUSTERED ( [AppointmentId] ASC ) ) GO ALTER TABLE [dbo].[Appointments] WITH CHECK ADD CONSTRAINT [FK_Appointments_ParentAppointments] FOREIGN KEY([RecurrenceParentId]) REFERENCES [dbo].[Appointments] ([AppointmentId]) GO ALTER TABLE [dbo].[Appointments] CHECK CONSTRAINT [FK_Appointments_ParentAppointments] GO

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  • How do you link to an action that takes an array as a parameter (RedirectToAction and/or ActionLink)

    - by Andrew
    I have an action defined like so: public ActionResult Foo(int[] bar) { ... } Url's like this will work as expected: .../Controller/Foo?bar=1&bar=3&bar=5 I have another action that does some work and then redirects to the Foo action above for some computed values of bar. Is there a simple way of specifying the route values with RedirectToAction or ActionLink so that the url's get generated like the above example? These don't seem to work: return RedirectToAction("Foo", new { bar = new[] { 1, 3, 5 } }); return RedirectToAction("Foo", new[] { 1, 3, 5 }); <%= Html.ActionLink("Foo", "Foo", new { bar = new[] { 1, 3, 5 } }) %> <%= Html.ActionLink("Foo", "Foo", new[] { 1, 3, 5 }) %> However, for a single item in the array, these do work: return RedirectToAction("Foo", new { bar = 1 }); <%= Html.ActionLink("Foo", "Foo", new { bar = 1 }) %> When setting bar to an array, it redirects to the following: .../Controller/Foo?a=System.Int32[] Finally, this is with ASP.NET MVC 2 RC. Thanks.

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  • x86 assembler question

    - by b-gen-jack-o-neill
    Hi, I have 2 simple, but maybe tricky questions. Let´s say I have assembler instruction: MOV EAX,[ebx+6*7] - what I am curious is, does this instruction really actually translates into opcode as it stands,so computation of code in brackets is encoded into opcode, or is this just pseudo intruction for compiler, not CPU, so that compiler before computes the value in brackets using add mul and so, store outcome in some reg and than uses MOV EAX,reg with computed value? Just to be clear, I know the output will be the same. I am interested in execution. Second is about LEA instruction. I know what it does, but I am more interested wheather its real instruction, so compiles does not further change it, just make it into opcode as it stands, or just pseudo code for compiler to, again, first compute adress and than store it.

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