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  • I have data about deadlocks, but I can't understand why they occur

    - by Alex
    I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL Profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second Linq-to-SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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  • How does Access 2007's moveNext/moveFirst/, etc., feature work?

    - by Chris M
    I'm not an Access expert, but am an SQL expert. I inherited an Access front-end referencing a SQL 2005 database that worked OK for about 5000 records, but is failing miserably for 800k records... Behind the scenes in the SQL profiler & activity manager I see some kind of Access query like: SELECT "MS1"."id" FROM "dbo"."customer" "MS1" ORDER BY "MS1"."id" The MS prefix doesn't appear in any Access code I can see. I'm suspicious of the built-in Access navigation code: DoCmd.GoToRecord , , acNext The GoToRecord has AcRecord constant, which includes things like acFirst, acLast, acNext, acPrevious and acGoTo. What does it mean in a database context to move to the "next" record? This particular table uses an identity column as the PK, so is it internally grabbing all the IDs and then moving to the one that is the next highest??? If so, how would it work if a table was comprised of three different fields for the PK? Or am I on the wrong track, and something else in Access is calling that statement? Unfortunately I see a ton of prepared statements in the profiler. THanks!

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  • Cannot create a new VS data connection in Server Explorer

    - by Seventh Element
    I have a local instance of SQL Server 2008 express edition running on my development PC. I'm trying to create a new data connection through Visual Studio Server Explorer. The steps are the following: Right click the "Data Connections" node = Choose Data Source. I select "Microsoft SQL Server" as the data source. The "Add Connection" dialog window appears. I select my local server instance = "Test connection" works fine. I select "AdventureWorks" as the database name = "Test connection" works fine. Next I hit the "Ok" button = Error message: "This server version is not supported. Only servers up to MS SQL Server 2005 are supported." I'm using Visual Studio 2008 Professional Edition. The target framework of the application is ".NET framework 3.5". I have a reference to System.Data (framework v2.0) and cannot find another version of the assembly on my system. Am I referencing the wrong assembly? How can I fix this problem?

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  • SQL developer here -- Nesting with select * finicky in Oracle 10g?

    - by John Sullivan
    I am writing a simple diagnostic query I will execute in my Oracle 10g scratchpad. I am trying to do this as part of a step to build the query. In the SQL Scratchpad for Oracle 10g Enterprise Manager Console, this statement runs fine. SELECT * FROM v$session sess, v$sql sql WHERE sql.sql_id(+) = sess.sql_id and sql.sql_text <> ' ' If I try to wrap that up in Select * from () tb2 I get an error, "ORA-00918: Column Ambiguously Defined". I didn't think that could ever happen with this kind of statement so I am a bit confused. select * from (SELECT * FROM v$session sess, v$sql sql WHERE sql.sql_id(+) = sess.sql_id and sql.sql_text <> ' ') tb2 You should always be able to select * from the result set of another select * statement using this structure as far as I'm aware... right? Is Oracle/10g/the scratchpad trying to force me to accept a certain syntactic structure to prevent excessive nesting? Is this a bug in scratchpad or something about how oracle works?

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  • Generating an NSDictionary from an SQL statement.

    - by Ed Wist
    I am trying to generate an NSDictonary that can be used to populate a listview with data I retrieved from an SQL statement. when I go to create an array and add them it adds the arrays for ALL my keys and not just for the current key. I've tried a removeAllObjects on the array but for some reason that destroys ALL my data that I already put in the dictionary. //open the database if(sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) { const char *sql = "select alphaID, word from words order by word"; sqlite3_stmt *selectStatement; //prepare the select statement int returnValue = sqlite3_prepare_v2(database, sql, -1, &selectStatement, NULL); if(returnValue == SQLITE_OK) { NSMutableArray *NameArray = [[NSMutableArray alloc] init]; NSString *alphaTemp = [[NSString alloc] init]; //loop all the rows returned by the query. while(sqlite3_step(selectStatement) == SQLITE_ROW) { NSString *currentAlpha = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectStatement, 1)]; NSString *definitionName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectStatement, 2)]; if (alphaTemp == nil){ alphaTemp = currentAlpha; } if ([alphaTemp isEqualToString:(NSString *)currentAlpha]) { [NameArray addObject:definitionName]; } else if (alphaTemp != (NSString *)currentAlpha) { [self.words setObject:NameArray forKey:currentAlpha]; [NameArray removeAllObjects]; [NameArray addObject:definitionName]; } } } The Statement above adds all the "keys" but then removes all the array elements for all keys. if I take out the removeAllKeys it adds ALL the array elements for ALL keys. I don't want this I want it to add the array elements FOR the specific key then move on to the next key. in the end I want a NSDictonary with A (array) Alpha (string) Apple (string) B (array) Beta (string) Ball (string) C (array) Code (string) ...

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  • mysql get table based on common column between two tables

    - by Zentdayn
    while trying to learn sql i came across "Learn SQL The Hard Way" and i started reading it. Everything was going fine then i thought ,as a way to practice, to make something like given example in the book (example consists in 3 tables pet,person,person_pet and the person_pet table 'links' pets to their owners). I made this: report table +----+-------------+ | id | content | +----+-------------+ | 1 | bank robbery| | 2 | invalid | | 3 | cat on tree | +----+-------------+ notes table +-----------+--------------------+ | report_id | content | +-----------+--------------------+ | 1 | they had guns | | 3 | cat was saved | +-----------+--------------------+ wanted result +-----------+--------------------+---------------+ | report_id | report_content | report_notes | +-----------+--------------------+---------------+ | 1 | bank robbery | they had guns | | 2 | invalid | null or '' | | 3 | cat on tree | cat was saved | +-----------+--------------------+---------------+ I tried a few combinations but no success. My first thought was SELECT report.id,report.content AS report_content,note.content AS note_content FROM report,note WHERE report.id = note.report_id but this only returns the ones that have a match (would not return the invalid report). after this i tried adding IF conditions but i just made it worse. My question is, is this something i will figure out after getting past basic sql or can this be done in simple way? Anyway i would appreciate any help, i pretty much lost with this. Thank you. EDIT: i have looked into related questions but havent yet found one that solves my problem. I probably need to look into other statements such as join or something to sort this out.

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  • Cannot disable index during PL/SQL procedure

    - by nw
    I've written a PL/SQL procedure that would benefit if indexes were first disabled, then rebuilt upon completion. An existing thread suggests this approach: alter session set skip_unusable_indexes = true; alter index your_index unusable; [do import] alter index your_index rebuild; However, I get the following error on the first alter index statement: SQL Error: ORA-14048: a partition maintenance operation may not be combined with other operations ORA-06512: [...] 14048. 00000 - "a partition maintenance operation may not be combined with other operations" *Cause: ALTER TABLE or ALTER INDEX statement attempted to combine a partition maintenance operation (e.g. MOVE PARTITION) with some other operation (e.g. ADD PARTITION or PCTFREE which is illegal *Action: Ensure that a partition maintenance operation is the sole operation specified in ALTER TABLE or ALTER INDEX statement; operations other than those dealing with partitions, default attributes of partitioned tables/indices or specifying that a table be renamed (ALTER TABLE RENAME) may be combined at will The problem index is defined so: CREATE INDEX A11_IX1 ON STREETS ("SHAPE") INDEXTYPE IS "SDE"."ST_SPATIAL_INDEX" PARAMETERS ('ST_GRIDS=890,8010,72090 ST_SRID=2'); This is a custom index type from a 3rd-party vendor, and it causes chronic performance degradation during high-volume update/insert/delete operations. Any suggestions on how to work around this error? By the way, this error only occurs within a PL/SQL block.

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  • Best ways to construct Dynamic Search Conditions for Sql

    - by CoolBeans
    I have always wondered what's the best way to achieve this task. In most web based applications you have to provide search options on many different criteria. Based on what criteria is chosen behind the scene you modify your SQL. Generally, this is how I tend to go about it:- Have a base SQL template. In the base template have conditions like this WHERE [#PRE_COND1] AND [#PRE_COND2] .. so on and so forth. So an example SQL might look something like SELECT NAME,AGE FROM PERSONS [,#TABLE2] [,#TABLE3] WHERE [#PRE_COND1] AND [#PRE_COND2] ORDER BY [#ORD_COND1] AND [#ORD_COND2] etc. During run time after figuring out the all the search criteria user has entered, I replace the [#PRE_COND1]s and [#ORD_COND1]s with the appropriate SQLs and then execute the query. I personally do not like this brute force method. However, I never came across a better approach either. How do you accomplish such tasks generally given you are either using native JDBC or Spring JDBC? It is almost like I need a C MACRO like functionality in Java to do this.

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  • Sync data between a windows desktop app and windows mobile client app

    - by Chris W
    I need to knock up a very quick prototype/proof of concept application to demo to someone within the next couple of days so I've minimal time to research this as fully as I normally would. The set-up is a very simple database application running on a laptop - will only ever be a single user updating a couple of tables so I was thinking of knocking up a basic Win Forms app against SQL Compact. Visual Studio's auto generated data grid edit screens will be fine with a little customisation. The second aspect is to then add a windows mobile client application that can pull data from both tables stored on the laptop, edit some data and insert some extra rows before sending the changes back to the laptop copy of the database. I've not done any WinMo development so what's the best approach for me to look at. Is it easy enough to sync data between the two databases when the WinMo device is connected to the laptop with USB? Most of the samples I've looked at so far seem to be syncing SQL Compact with SQL Standard using IIS which seems a bit overkill. The volumes of data to be synced are so small that I can easily write some manual sync code if it's easy for me to query/update the Compact DB from the laptop application when the device is connected.

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  • Java saying XML Document Not Well Formed

    - by Pyroclastic
    Hey all. Java's XML parser seems to be thinking that my XML document is not well formed following the root element, but I've validated it with several tools and they all disagree. It's probably an error in my code rather than in the document itself, I'd really appreciate any help you all could offer me. Here is my Java method: private void loadFromXMLFile(File f) throws ParserConfigurationException, IOException, SAXException { File file = f; DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db; Document doc = null; db = dbf.newDocumentBuilder(); doc = db.parse(file); doc.getDocumentElement().normalize(); String desc = ""; String due = ""; String comment = ""; NodeList tasksList = doc.getElementsByTagName("task"); for (int i = 0; i < tasksList.getLength(); i++) { NodeList attributes = tasksList.item(i).getChildNodes(); for (int j = 0; i < attributes.getLength(); j++) { Node attribute = attributes.item(i); if (attribute.getNodeName() == "description") { desc = attribute.getTextContent(); } if (attribute.getNodeName() == "due") { due = attribute.getTextContent(); } if (attribute.getNodeName() == "comment") { comment = attribute.getTextContent(); } tasks.add(new Task(desc, due, comment)); } desc = ""; due = ""; comment = ""; } } And here is the XML file I'm trying to load: <?xml version="1.0"?> <tasklist> <task> <description>Task 1</description> <due>Due date 1</due> <comment>Comment 1</comment> <completed>false</completed> </task> <task> <description>Task 2</description> <due>Due date 2</due> <comment>Comment 2</comment> <completed>false</completed> </task> <task> <description>Task 3</description> <due>Due date 3</due> <comment>Comment 3</comment> <completed>true</completed> </task> </tasklist> And here is the error message java is throwing for me: run: [Fatal Error] tasks.xml:28:3: The markup in the document following the root element must be well-formed. May 17, 2010 6:07:02 PM todolist.TodoListGUI SEVERE: null org.xml.sax.SAXParseException: The markup in the document following the root element must be well-formed. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:239) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283) at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:208) at todolist.TodoListGUI.loadFromXMLFile(TodoListGUI.java:199) at todolist.TodoListGUI.(TodoListGUI.java:42) at todolist.Main.main(Main.java:25) BUILD SUCCESSFUL (total time: 19 seconds) For reference TodoListGUI.java:199 is doc = db.parse(file); If context is helpful to anyone here, I'm trying to write a simple GUI application to manage a todo list that can read and write to and from XML files defining the tasks. Any advice is appreciated!

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  • Checking if user owns file before deleting it

    - by Martin Hoe
    I'm building an API for my site that allows users to delete the files they upload. Obviously, I want to check if the user owns that file before they delete it through the API. I have a files table and a users table, here's the schema: f_id, s_id, u_id, name, size, uploaded u_id, username, password, email, activated, activation_code u_id is a foreign key. The u_id field in the files table points to the u_id in the users table. Given the users username, I want to find the users u_id, and then check if they own the file through the file ID (f_id). I wrote this SQL: $sql = 'SELECT u.username FROM `users` u JOIN `files` f ON u.u_id = f.u_id WHERE f_id = ? AND u.u_id = ? LIMIT 1'; I'm assuming that'd work if I was given the users u_id in the API request, but alas I'm given only their username. How can I modify that SQL to find their user ID and use that? Thanks. Edit: Alright I've got this query but it's always returning an empty result set even though both the file ID and username exist. SELECT u.username FROM `users` u JOIN `files` f ON u.u_id = f.u_id WHERE f.f_id = ? AND u.username = ? LIMIT 1

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  • Java doest run prepare statements with parameter

    - by Zaiman Noris
    If using PreparedStatement to query my table. Unfortunately, I have not been able to do so. My code is as simple as this :- PreparedStatement preparedStatement = connection.prepareStatement( "Select favoritefood from favoritefoods where catname = ?"); preparedStatement.setString(1, "Cappuccino"); ResultSet resultSet = preparedStatement.executeQuery(); Error thrown is java.sql.SQLException: ORA-00911: invalid character. As if it never run through the parameter given. Thanks for your time. I've spend a day to debug this yet still unsuccessful. As mention by Piyush, if I omit the semicolon at the end of statement, new error is thrown. java.sql.SQLException: ORA-00942: table or view does not exist. But I can assure you this table is indeed exist. UPDATE shoot. i edited the wrong sql. now it is successful. thx for your time.

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  • Dealing with large number of text strings

    - by Fadrian
    My project when it is running, will collect a large number of string text block (about 20K and largest I have seen is about 200K of them) in short span of time and store them in a relational database. Each of the string text is relatively small and the average would be about 15 short lines (about 300 characters). The current implementation is in C# (VS2008), .NET 3.5 and backend DBMS is Ms. SQL Server 2005 Performance and storage are both important concern of the project, but the priority will be performance first, then storage. I am looking for answers to these: Should I compress the text before storing them in DB? or let SQL Server worry about compacting the storage? Do you know what will be the best compression algorithm/library to use for this context that gives me the best performance? Currently I just use the standard GZip in .NET framework Do you know any best practices to deal with this? I welcome outside the box suggestions as long as it is implementable in .NET framework? (it is a big project and this requirements is only a small part of it) EDITED: I will keep adding to this to clarify points raised I don't need text indexing or searching on these text. I just need to be able to retrieve them in later stage for display as a text block using its primary key. I have a working solution implemented as above and SQL Server has no issue at all handling it. This program will run quite often and need to work with large data context so you can imagine the size will grow very rapidly hence every optimization I can do will help.

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  • calculating change (over a period) for a dated field

    - by morpheous
    I have two tables with the following schema: CREATE TABLE sales_data ( sales_time date NOT NULL, product_id integer NOT NULL, sales_amt double NOT NULL ); CREATE TABLE date_dimension ( id integer NOT NULL, datestamp date NOT NULL, day_part integer NOT NULL, week_part integer NOT NULL, month_part integer NOT NULL, qtr_part integer NOT NULL, year_part integer NOT NULL, ); I want to write two types of queries that will allow me to calculate: period on period change (e.g. week on week change) change in period on period change (e.g. change in week on week change) I would prefer to write this in ANSI SQL, since I dont want to be tied to any particular db. [Edit] In light of some of the comments, if I have to be tied to a single database (in terms of SQL dialect), it will have to be PostgreSQL The queries I want to write are of the form (pseudo SQL of course): Query Type 1 (Period on Period Change) ======================================= a). select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as week_on_week_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) b). select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as month_on_month_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) Query Type 2 (Change in Period on Period Change) ================================================= a). select product_id, ((a2.week_on_week_change - a1.week_on_week_change)/a1.week_on_week_change) as change_on_week_on_week_change from (select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as week_on_week_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) as a1), (select product_id, ((sd2.sales_amt - sd1.sales_amt)/sd1.sales_amt) as week_on_week_change from sales_data sd1, sales_data sd2, date_dimension dd where {SOME CRITERIA) as a2) WHERE {SOME OTHER CRITERIA}

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  • Cannot bulk load. The file "c:\data.txt" does not exist.

    - by Daniel Brink
    Hi, I'm having a problem reading data from a text file into ms sql. I created a text file in my c:\ called data.txt, but for some reason ms sql server cannot find the file. I get the error "Cannot bulk load. The file "c:\data.txt" does not exist." Any ideas? The data file (yes I know the data looks crappy, but in the real world thats how it comes from clients): 01-04 10.338,18 0,00 597.877,06- 5 0,7500 62,278- 06-04 91.773,00 9.949,83 679.700,23- 1 0,7500 14,160- 07-04 60.648,40 149.239,36 591.109,27- 1 0,7500 12,314- 08-04 220.173,70 213.804,37 597.478,60- 1 0,7500 12,447- 09-04 986.071,39 0,00 1.583.549,99- 3 0,7500 98,971- 12-04 836.049,00 1.325.234,79 1.094.364,20- 1 0,7500 22,799- 13-04 38.000,00 503.010,49 629.353,71- 1 0,7500 13,111- 14-04 286.400,00 840.126,50 75.627,21- 1 0,7500 1,575- The Sql: CREATE TABLE #temp ( vchCol1 VARCHAR (50), vchCol2 VARCHAR (50), vchCol3 VARCHAR (50), vchCol4 VARCHAR (50), vchCol5 VARCHAR (50), vchCol6 VARCHAR (50), vchCol7 VARCHAR (50) ) BULK insert #temp FROM 'c:\data.txt' WITH ( FIELDTERMINATOR = ' ', ROWTERMINATOR = '\n' ) select * from #temp drop table #temp

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  • Will these security functions be enough? (PHP)

    - by ggfan
    I am trying to secure my site so I don't have sql injections and xss scripting. Here's my code. //here's the from, for brevity, i just show a field for users to put firstname <form> <label for="first_name" class="styled">First Name:</label> <input type="text" id="first_name" name="first_name" value="<?php if (!empty($first_name)) echo $first_name; ?>" /><br /> //submit button etc </form> if (isset($_POST['submit'])) { //gets rid of extra whitesapce and escapes $first_name = mysqli_real_escape_string($dbc, trim($_POST['first_name'])); //check if $first_name is a string if(!is_string($first_name) { echo "not string"; } //then insert into the database. ....... } mysqli_real_espace_string: I know that this func escapes certain letters like \n \r, so when the data gets inputted into the dbc, it would have '\' next to all the escaped letters? --Will this script be enough to prevent most sql injections? just escaping and checking if the data is a string. For integers values(like users putting in prices), i just: is_numeric(). --How should I use htmlspecialchars? Should I use it only when echoing and displaying user data? Or should I also use this too when inputting data to a dbc? --When should I use strip_tags() or htmlspecialchars? SOO with all these function... if (isset($_POST['submit'])) { //gets rid of extra whitesapce and escapes $first_name = mysqli_real_escape_string($dbc, trim($_POST['first_name'])); //check if $first_name is a string if(!is_string($first_name) { echo "not string"; } //gets rid of any <,>,& htmlspecialchars($first_name); //strips any tags with the first name strip_tags($first_name) //then insert into the database. ....... } Which funcs should I use for sql injections and which ones should I use for xss?

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  • Storing Number in an integer from sql Database

    - by ar31an
    i am using database with table RESUME and column PageIndex in it which type is number in database but when i want to store this PageIndex value to an integer i get exception error Specified cast is not valid. here is the code string sql; string conString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=D:\\Deliverable4.accdb"; protected OleDbConnection rMSConnection; protected OleDbDataAdapter rMSDataAdapter; protected DataSet dataSet; protected DataTable dataTable; protected DataRow dataRow; on Button Click sql = "select PageIndex from RESUME"; rMSConnection = new OleDbConnection(conString); rMSDataAdapter = new OleDbDataAdapter(sql, rMSConnection); dataSet = new DataSet("pInDex"); rMSDataAdapter.Fill(dataSet, "RESUME"); dataTable = dataSet.Tables["RESUME"]; int pIndex = (int)dataTable.Rows[0][0]; rMSConnection.Close(); if (pIndex == 0) { Response.Redirect("Create Resume-1.aspx"); } else if (pIndex == 1) { Response.Redirect("Create Resume-2.aspx"); } else if (pIndex == 2) { Response.Redirect("Create Resume-3.aspx"); } } i am getting error in this line int pIndex = (int)dataTable.Rows[0][0];

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  • Coalesce and Case-When with To_Date not working as expected (Postgres bug?)

    - by ADTC
    I'm using Postgres 9.1. The following query does not work as expected. Coalesce should return the first non-null value. However, this query returns null (1?) instead of the date (2). select COALESCE( TO_DATE('','yyyymmdd'), --(1) TO_DATE('20130201','yyyymmdd') --(2) ); --(1) this evaluates independently to null --(2) this evaluates independently to the date, and therefore is the first non-null value What am I doing wrong? Any workaround? Edit: This may have nothing to do with Coalesce at all. I tried some experiments with Case When constructs; it turns out, Postgres has this big ugly bug where it treats TO_DATE('','yyyymmdd') as not null, even though selecting it returns null.

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  • How to join by column name

    - by Daniel Vaca
    I have a table T1 such that gsdv |nsdv |esdv ------------------- 228.90 |216.41|0.00 and a table T2 such that ds |nm -------------------------- 'Non-Revenue Sales'|'ESDV' 'Gross Sales' |'GSDV' 'Net Sales' |'NSDV' How do I get the following table? ds |nm |val --------------------------------- 'Non-Revenue Sales'|'ESDV'|0.00 'Gross Sales' |'GSDV'|228.90 'Net Sales' |'NSDV'|216.41 I know that I can this by doing the following SELECT ds,nm,esdv val FROM T1,T2 WHERE nm = 'esdv' UNION SELECT ds,nm,gsdv val FROM T1,T2 WHERE nm = 'gsdv' UNION SELECT ds,nm,nsdv val FROM T1,T2 WHERE nm = 'nsdv' but I am looking for a more generic/nicer solution. I am using Sybase, but if you can think of a way to do this with other DBMS, please let me know. Thanks.

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  • What db fits me?

    - by afvasd
    Dear Everyone I am currently using mysql. I am finding that my schema is getting incredibly complicated. I seek to find a new db that will suit my needs: Let's assume I am building a news aggregrator (which collects news from multiple website). I then run algorithms to determine if two news from different sites are actually referring to the same topic. I run this algorithm to cluster news together. The relationship is depicted below: cluster \--news1 \--word1 \--word2 \--news2 \--word3 \--news3 \--word1 \--word3 And then I will apply some magic and determine the importance of each word. Summing all the importance of each word gives me the importance of a news article. Summing the importance of each news article gives me the importance of a cluster. Note that above cluster there are also subgroups( like split by region etc), and categories (like sports, etc) which I have to determine the importance of that in a particular day per se. I have used views in the past to do so, but I realized that views are very slow. So i will normally do an insert into an actual table and index them for better performance. As you can see this leads to multiple tables derived like (cluster, importance), (news, importance), (words, importance) etc which can get pretty messy. Also the "importance" metric will change. It has become increasingly difficult to alter tables, update data (which I am using TRUNCATE TABLE) and then inserting from null. I am currently looking into something schemaless like Mongodb. I do not need distributedness. I would very much want something that is reasonably fast (which can be indexed) and something that is a lot more flexible that traditional RDMBS. Also, I need something that has some kind of ORM because I personally like ORM a lot. I am currently using sqlalchemy Please help!

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  • Composable FLinq expressions

    - by Daniel
    When doing linq-to-sql in c#, you could do something like this: var data = context.MyTable.Where(x => x.Parameter > 10); var q1 = data.Take(10); var q2 = data.Take(3); q1.ToArray(); q2.ToArray(); This would generate 2 separate SQL queries, one with TOP 10, and the other with TOP 3. In playing around with Flinq, I see that: let data = query <@ seq { for i in context.MyTable do if x.Parameter > 10 then yield i } @> data |> Seq.take 10 |> Seq.toList data |> Seq.take 3 |> Seq.toList is not doing the same thing. Here it seems to do one full query, and then do the "take" calls on the client side. An alternative that I see used is: let q1 = query <@ for i in context.MyTable do if x.Param > 10 then yield i } |> Seq.take 10 @> let q2 = query <@ for i in context.MyTable do if x.Param > 10 then yield i } |> Seq.take 3 @> These 2 generate the SQL with the appropriate TOP N filter. My problem with this is that it doesn't seem composable. I'm basically having to duplicate the "where" clause, and potentially would have to duplicate other other subqueries that I might want to run on a base query. Is there a way to have F# give me something more composable? (I originally posted this question to hubfs, where I have gotten a few answers, dealing with the fact that C# performs the query transformation "at the end", i.e. when the data is needed, where F# is doing that transformation eagerly.)

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