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• How do I disable Windows authentication on a SQL Server instance?

  - by leonita

  How do I disable Windows authentication on a SQL Server instance?

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• Looking for free, specific Ip2Location Database

  - by Andresch Serj

  I am searching for a free db (like an updated XML or CSV file) that relates IP addresses to specific locations. I want more information than just the country. I want some sort of region or city reference, even if that ends up to be a number that makes no sense to me. Doesn't have to be super correct or always up to date either. It is just to distinguish between user groups and not to monitor or spy on them.

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• ServerName no longer works as SQL Server 2008 Default instance name?

  - by TomK

  Folks, Somehow in struggling to install something (Sage MIP), I have unsettled my system's SQL Server 2008 instance names. If I fired up SSMS and connected to "MySystemName" (while logged into MySystemName), I used to immediately connect and could view my databases. Now if I connect to "(local)" or "." I connect just fine...but "MySystemName" gives me a timeout error. If I log in with "." and do "SELECT @@SERVERNAME" it comes back with "MySystemName" just fine. I've double checked that my network name is in the Security\Logins list, and it is, as a dbadmin. Any suggestions? I thought that having SQL Server 2005 Express might be a problem (the "battle of the default instances"), so I uninstalled that. No better.

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• Make huge space savings by using SPARSE columns

  - by simonsabin

  I’ve blogged before about Getting more than 1024 columns on a table , this is done by using sparse columns. Whilst this is potentially useful for people with insane table designs, sparse columns aren’t just for this. My experience over the past few years has shown that sparse columns are useful for almost all databases when you have columns that are largely null i.e. sparse. A recent client was able to reduce the size of the table by 60% by changing columns to sparse. The way this is achieved is...(read more)

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• Découverte d'une faille de sécurité critique dans iOS, une application malveillante se retrouve sur l'App Store

  Découverte d'une faille de sécurité critique dans iOS une application malveillante se retrouve sur l'App Store Charlie Miller, un ancien analyste de la NSA, reconnu pour avoir déjà trouvé plusieurs vulnérabilités dans les systèmes d'Apple, vient de révéler une nouvelle faille critique dans les terminaux iOS. La faille se situe au niveau du moteur JavaScript du navigateur Safari dans la politique de restriction de la signature de code, qui permet d'exécuter des commandes non autorisées dans un espace de la mémoire du dispositif. La vulnérabilité peut-être exploitée par des pirates pour exécuter du code distant, voler ou détruire les données des utilisateurs et envoy...

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• Mirroring: what happens if principal loses contact with both mirror and wittness?

  - by TiborKaraszi

  Imagine a database mirroring setup where you have two LANs with a WAN link in between. Let's call them site A and site B. Say that principal is currently in site A, and both mirror and witness are in site B. I.e., we are running database mirroring with a witness, and assuming we are running safety FULL (synchronous), we have auto-fail over. Now, what is really fail over when it comes to mirroring? the simple answer is that the mirror will finish the recovery process (UNDO) and make the database available....(read more)

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• Continuous Delivery and the Database

  Continuous Delivery is fairly generally understood to be an effective way of tackling the problems of software delivery and deployment by making build, integration and delivery into a routine. The way that databases fit into the Continuous Delivery story has been less-well defined. Phil Factor explains why he's an enthusiast for databases being full participants, and suggests practical ways of doing so.

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• Chapter 7–Enforced Data Protection

  - by drsql

  As the book progresses, I find myself veering from the original stated outline quite a bit, because as I teach about this more (and I am teaching a daylong db design class in August at http://www.sqlsolstice.com/ … shameless plug, but it is on topic :) I start to find that a given order works better. Originally I had slated myself to talk more about modeling here for three chapters, then get back to the more implementation topics to finish out the book, but now I am going to keep plugging through...(read more)

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• Database in the cloud?

  - by Jlouro

  Some of my recent clients are asking for remote connections to the office server, for standalone work, etc, in winForm applications. Since the concept of the web is remote connection to a server both of data and resources, it should be possible to place both of this in cloud and have the winForm apps connect to it as if web Apps. As any one tested this, is working like this? Is it fast enough? Is it secure? What is the best cloud host for this type of work ?

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• When adding second processor to SQL Server, will it automatically balance the load?

  - by ddavis

  We have a SQL Server 2008 R2 (10.5) on a dedicated box with a single 2.4Ghz processor, which regularly runs at 70-80% CPU. We are going to be adding a significant number of users to the application and therefore want to add a second processor to the box (scale up). Will SQL Server automatically use the second processor to balance threads, or is there additional configuration that will need to be done? In other words, will adding the second processor drop my CPU usage to 35-40% per CPU, automatically balancing the load? Based on what I read here, it seems that it will: http://msdn.microsoft.com/en-us/library/ms181007.aspx However, I've read elsewhere that CPU performance gains can be made by assigning database tables to different filegroups, but I'm not sure we want to get that complicated at this point.

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• Set modified date = created date or null on record creation?

  - by User

  I've been following the convention of adding created and modified columns to most of my database tables. I also have been leaving the modified column as null on record creation and only setting a value on actual modification. The other alternative is to set the modified date to be equal to created date on record creation. I've been doing it the former way but I recent ran into one con which is seriously making me think of switching. I needed to set a database cache dependency to find out if any existing data has been changed or new data added. Instead of being able to do the following: SELECT MAX(modified) FROM customer I have to do this: SELECT GREATEST(MAX(created), MAX(modified)) FROM customer The negative being that it's a more complicated query and slower. Another thing is in file systems I believe they usually use the second convention of setting modified date = created date on creation. What are the pros and cons of the different methods? That is, what are the issues to consider?

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• SQL Insert Into Statement

  - by Derek Dieter

  The “insert into” statement is used in order to insert data into an existing table. The syntax for this is fairly simple. In the first section of the statement, you specify the table name and column names in which you are inserting data into. The second part is where the source of [...]

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• Another website is mirroring and ranks above my site in search results

  - by Marlboro Goodluck

  There is a site of ill-repute known as thedirty which has completely mirrored my site and now has links appearing on Google at the #1 spot using my content. I checked my log files and noticed that this site has been crawling mine for sometime, and also has 10,000 links from their site to mine. I have blocked user access which is referred from this site and reported them as web spam to Google already. I also disavowed the domain. How are they getting top links in Google (even overtaking mine) for such nefarious tactics? What are the steps to completely eliminating an issue such as this?

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• How should I implement Transaction database EJB 3.0

  - by JamesBoyZ

  In the CustomerTransactions entity, I have the following field to record what the customer bought: @ManyToMany private List<Item> listOfItemsBought; When I think more about this field, there's a chance it may not work because merchants are allowed to change item's information (e.g. price, discount, etc...). Hence, this field will not be able to record what the customer actually bought when the transaction occurred. At the moment, I can only think of 2 ways to make it work. I will record the transaction details into a String field. I feel that this way would be messy if I need to extract some information about the transaction later on. Whenever the merchant changes an item's information, I will not update directly to that item's fields. Instead, I will create another new item with all the new information and keep the old item untouched. I feel that this way is better because I can easily extract information about the transaction later on. However, the bad side is that my Item table may contain a lot of rows. I'd be very grateful if someone could give me an advice on how I should tackle this problem. UPDATE: I'd like to add more information about the current design. public class Customer implements Serializable { @OneToMany private List<CustomerTransactions> listOfTransactions; } public class CustomerTransactions implements Serializable { @ManyToMany private List<Item> listOfItemsBought; } public class Merchant implements Serializable { @OneToMany private List<Item> listOfSellingItems; }

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• Another website is mirroring my site

  - by Marlboro Goodluck

  Question for you all. There is a site of ill repute known as thedirty which has completely mirrored my site and now has links appearing on Google at the #1 spot using my content. I checked my log file and noticed that this site has been crawling mine from sometime, and also has 10k links from their site to mine. I have blocked user access which is referred from this site and reported them as web spam to Google already. I also disavowed the domain. How are they getting top links in Google (even overtaking mine) for such nefarious tactics? What are the steps to completely eliminating an issue such as this?

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• SQL*Plus??? - SPOOL??????(????? ???Tips-5)

  - by Yuichi.Hayashi

  SQL??????????????????????????????????????SPOOL?????????????? ???SPOOL??????????????????????????????? ????????? ????????????????????????????????????????????????????????????????????    $ sqlplus @sample.sql > /dev/null ??????????????????????????????? ??????????SPOOL????????????????? arraysize???????? arraysize???????SELECT??????fetch?????????SQL*Plus????????? ????????SPOOL????????SELECT???????????? SPOOL????     SQL> set array[size] 100 ????????fetch?100?????????????15???? ???????????????????????????????????????????????????? ????????????????????????????????????????????????????????????? ?????????????????????????????????????????????? ?????????? SPOOL?????????????1?????linesize???????????????????????????????? ????????????????????????????????????????? ????????????SPOOL????    SQL> set trims[pool] on ????????????off???????????????? ?????????? ???????????????SQL*Plus????????????1????????????????????????????????????????????????????????? ??????????????????????   (Written by Hiroyuki Nakaie) ?????SQL*Plus TIPS???????????????? Oracle SQL*Plus - ??, ??, ?????

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• ??????Oracle Enterprise Manager???????

  - by Yusuke.Yamamoto

  ????? ??:2010/10/19 ??:???? ?????????????????????????????????????????????????? Oracle Enterprise Manager(EM)????????????4?????EM ???????????????????????? ?1? ???????????????/ ???????????? Oracle Database????????????????EM ??????????????????2? EM ??????????/ ????????????? EM?????????????????????3? ????????????·???/ ????????????????Enterprise Edition ?????????Standard Edition ?????????????????????????????????·???????4? ?????????????????/ Oracle Database ???????? EM ?????????????????????????????????????????·????·?????? ????????? ????????????????? http://oracletech.jp/products/pickup/000028.html

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• Handling inheritance with overriding efficiently

  - by Fyodor Soikin

  I have the following two data structures. First, a list of properties applied to object triples: Object1 Object2 Object3 Property Value O1 O2 O3 P1 "abc" O1 O2 O3 P2 "xyz" O1 O3 O4 P1 "123" O2 O4 O5 P1 "098" Second, an inheritance tree: O1 O2 O4 O3 O5 Or viewed as a relation: Object Parent O2 O1 O4 O2 O3 O1 O5 O3 O1 null The semantics of this being that O2 inherits properties from O1; O4 - from O2 and O1; O3 - from O1; and O5 - from O3 and O1, in that order of precedence. NOTE 1: I have an efficient way to select all children or all parents of a given object. This is currently implemented with left and right indexes, but hierarchyid could also work. This does not seem important right now. NOTE 2: I have tiggers in place that make sure that the "Object" column always contains all possible objects, even when they do not really have to be there (i.e. have no parent or children defined). This makes it possible to use inner joins rather than severely less effiecient outer joins. The objective is: Given a pair of (Property, Value), return all object triples that have that property with that value either defined explicitly or inherited from a parent. NOTE 1: An object triple (X,Y,Z) is considered a "parent" of triple (A,B,C) when it is true that either X = A or X is a parent of A, and the same is true for (Y,B) and (Z,C). NOTE 2: A property defined on a closer parent "overrides" the same property defined on a more distant parent. NOTE 3: When (A,B,C) has two parents - (X1,Y1,Z1) and (X2,Y2,Z2), then (X1,Y1,Z1) is considered a "closer" parent when: (a) X2 is a parent of X1, or (b) X2 = X1 and Y2 is a parent of Y1, or (c) X2 = X1 and Y2 = Y1 and Z2 is a parent of Z1 In other words, the "closeness" in ancestry for triples is defined based on the first components of the triples first, then on the second components, then on the third components. This rule establishes an unambigous partial order for triples in terms of ancestry. For example, given the pair of (P1, "abc"), the result set of triples will be: O1, O2, O3 -- Defined explicitly O1, O2, O5 -- Because O5 inherits from O3 O1, O4, O3 -- Because O4 inherits from O2 O1, O4, O5 -- Because O4 inherits from O2 and O5 inherits from O3 O2, O2, O3 -- Because O2 inherits from O1 O2, O2, O5 -- Because O2 inherits from O1 and O5 inherits from O3 O2, O4, O3 -- Because O2 inherits from O1 and O4 inherits from O2 O3, O2, O3 -- Because O3 inherits from O1 O3, O2, O5 -- Because O3 inherits from O1 and O5 inherits from O3 O3, O4, O3 -- Because O3 inherits from O1 and O4 inherits from O2 O3, O4, O5 -- Because O3 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 O4, O2, O3 -- Because O4 inherits from O1 O4, O2, O5 -- Because O4 inherits from O1 and O5 inherits from O3 O4, O4, O3 -- Because O4 inherits from O1 and O4 inherits from O2 O5, O2, O3 -- Because O5 inherits from O1 O5, O2, O5 -- Because O5 inherits from O1 and O5 inherits from O3 O5, O4, O3 -- Because O5 inherits from O1 and O4 inherits from O2 O5, O4, O5 -- Because O5 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 Note that the triple (O2, O4, O5) is absent from this list. This is because property P1 is defined explicitly for the triple (O2, O4, O5) and this prevents that triple from inheriting that property from (O1, O2, O3). Also note that the triple (O4, O4, O5) is also absent. This is because that triple inherits its value of P1="098" from (O2, O4, O5), because it is a closer parent than (O1, O2, O3). The straightforward way to do it is the following. First, for every triple that a property is defined on, select all possible child triples: select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value from TriplesAndProperties tp -- Select corresponding objects of the triple inner join Objects as Objects1 on Objects1.Id = tp.O1 inner join Objects as Objects2 on Objects2.Id = tp.O2 inner join Objects as Objects3 on Objects3.Id = tp.O3 -- Then add all possible children of all those objects inner join Objects as Children1 on Objects1.Id [isparentof] Children1.Id inner join Objects as Children2 on Objects2.Id [isparentof] Children2.Id inner join Objects as Children3 on Objects3.Id [isparentof] Children3.Id But this is not the whole story: if some triple inherits the same property from several parents, this query will yield conflicting results. Therefore, second step is to select just one of those conflicting results: select * from ( select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value, row_number() over( partition by Children1.Id, Children2.Id, Children3.Id, tp.Property order by Objects1.[depthInTheTree] descending, Objects2.[depthInTheTree] descending, Objects3.[depthInTheTree] descending ) as InheritancePriority from ... (see above) ) where InheritancePriority = 1 The window function row_number() over( ... ) does the following: for every unique combination of objects triple and property, it sorts all values by the ancestral distance from the triple to the parents that the value is inherited from, and then I only select the very first of the resulting list of values. A similar effect can be achieved with a GROUP BY and ORDER BY statements, but I just find the window function semantically cleaner (the execution plans they yield are identical). The point is, I need to select the closest of contributing ancestors, and for that I need to group and then sort within the group. And finally, now I can simply filter the result set by Property and Value. This scheme works. Very reliably and predictably. It has proven to be very powerful for the business task it implements. The only trouble is, it is awfuly slow. One might point out the join of seven tables might be slowing things down, but that is actually not the bottleneck. According to the actual execution plan I'm getting from the SQL Management Studio (as well as SQL Profiler), the bottleneck is the sorting. The problem is, in order to satisfy my window function, the server has to sort by Children1.Id, Children2.Id, Children3.Id, tp.Property, Parents1.[depthInTheTree] descending, Parents2.[depthInTheTree] descending, Parents3.[depthInTheTree] descending, and there can be no indexes it can use, because the values come from a cross join of several tables. EDIT: Per Michael Buen's suggestion (thank you, Michael), I have posted the whole puzzle to sqlfiddle here. One can see in the execution plan that the Sort operation accounts for 32% of the whole query, and that is going to grow with the number of total rows, because all the other operations use indexes. Usually in such cases I would use an indexed view, but not in this case, because indexed views cannot contain self-joins, of which there are six. The only way that I can think of so far is to create six copies of the Objects table and then use them for the joins, thus enabling an indexed view. Did the time come that I shall be reduced to that kind of hacks? The despair sets in.

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• T-SQL: Compute Subtotals For A Range Of Rows

  - by John Dibling

  MSSQL 2008. I am trying to construct a SQL statement which returns the total of column B for all rows where column A is between 2 known ranges. The range is a sliding window, and should be recomputed as it might be using a loop. Here is an example of what I'm trying to do, much simplified from my actual problem. Suppose I have this data: table: Test Year Sales ----------- ----------- 2000 200 2001 200 2002 200 2003 200 2004 200 2005 200 2006 200 2007 200 2008 200 2009 200 2010 200 2011 200 2012 200 2013 200 2014 200 2015 200 2016 200 2017 200 2018 200 2019 200 I want to construct a query which returns 1 row for every decade in the above table, like this: Desired Results: DecadeEnd TotalSales --------- ---------- 2009 2000 2010 2000 Where the first row is all the sales for the years 2000-2009, the second for years 2010-2019. The DecadeEnd is a sliding window that moves forward by a set ammount for each row in the result set. To illustrate, here is one way I can accomplish this using a loop: declare @startYear int set @startYear = (select top(1) [Year] from Test order by [Year] asc) declare @endYear int set @endYear = (select top(1) [Year] from Test order by [Year] desc) select @startYear, @endYear create table DecadeSummary (DecadeEnd int, TtlSales int) declare @i int -- first decade ends 9 years after the first data point set @i = (@startYear + 9) while @i <= @endYear begin declare @ttlSalesThisDecade int set @ttlSalesThisDecade = (select SUM(Sales) from Test where(Year <= @i and Year >= (@i-9))) insert into DecadeSummary values(@i, @ttlSalesThisDecade) set @i = (@i + 9) end select * from DecadeSummary This returns the data I want: DecadeEnd TtlSales ----------- ----------- 2009 2000 2018 2000 But it is very inefficient. How can I construct such a query?

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• How to analyze 'dbcc memorystatus' result in SQL Server 2008

  - by envykok

  Currently i am facing a sql memory pressure issue. i have run 'dbcc memorystatus', here is part of my result: Memory Manager KB VM Reserved 23617160 VM Committed 14818444 Locked Pages Allocated 0 Reserved Memory 1024 Reserved Memory In Use 0 Memory node Id = 0 KB VM Reserved 23613512 VM Committed 14814908 Locked Pages Allocated 0 MultiPage Allocator 387400 SinglePage Allocator 3265000 MEMORYCLERK_SQLBUFFERPOOL (node 0) KB VM Reserved 16809984 VM Committed 14184208 Locked Pages Allocated 0 SM Reserved 0 SM Committed 0 SinglePage Allocator 0 MultiPage Allocator 408 MEMORYCLERK_SQLCLR (node 0) KB VM Reserved 6311612 VM Committed 141616 Locked Pages Allocated 0 SM Reserved 0 SM Committed 0 SinglePage Allocator 1456 MultiPage Allocator 20144 CACHESTORE_SQLCP (node 0) KB VM Reserved 0 VM Committed 0 Locked Pages Allocated 0 SM Reserved 0 SM Committed 0 SinglePage Allocator 3101784 MultiPage Allocator 300328 Buffer Pool Value Committed 1742946 Target 1742946 Database 1333883 Dirty 940 In IO 1 Latched 18 Free 89 Stolen 408974 Reserved 2080 Visible 1742946 Stolen Potential 1579938 Limiting Factor 13 Last OOM Factor 0 Page Life Expectancy 5463 Process/System Counts Value Available Physical Memory 258572288 Available Virtual Memory 8771398631424 Available Paging File 16030617600 Working Set 15225597952 Percent of Committed Memory in WS 100 Page Faults 305556823 System physical memory high 1 System physical memory low 0 Process physical memory low 0 Process virtual memory low 0 Procedure Cache Value TotalProcs 11382 TotalPages 430160 InUsePages 28 Can you lead me to analyze this result ? Is it a lot execute plan have been cached causing the memory issue or other reasons?

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• Generating the query plan takes 5 minutes, the query itself runs in milliseconds. What's up?

  - by TheImirOfGroofunkistan

  I have a fairly complex (or ugly depending on how you look at it) stored procedure running on SQL Server 2008. It bases a lot of the logic on a view that has a pk table and a fk table. The fk table is left joined to the pk table slightly more than 30 times (the fk table has a poor design - it uses name value pairs that I need to flatten out. Unfortunately, it's 3rd party and I cannot change it). Anyway, it had been running fine for weeks until I periodically noticed a run that would take 3-5 minutes. It turns out that this is the time it takes to generate the query plan. Once the query plan exists and is cached, the stored procedure itself runs very efficiently. Things run smoothly until there is a reason to regenerate and cache the query plan again. Has anyone seen this? Why does it take so long to generate the plan? Are there ways to make it come up with a plan faster?

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• Finding duplicate rows in SQL Server

  - by xtine

  I have a SQL Server database of organizations, and there are many duplicate rows. I want to run a select statement to grab all of these and the amount of dupes, but also return the ids that are associated with each organization. A statement like: SELECT orgName, COUNT(*) AS dupes FROM organizations GROUP BY orgName HAVING (COUNT(*) > 1) Will return something like orgName | dupes ABC Corp | 7 Foo Federation | 5 Widget Company | 2 But I'd also like to grab the IDs of them. Is there any way to do this? Maybe like a orgName | dupeCount | id ABC Corp | 1 | 34 ABC Corp | 2 | 5 ... Widget Company | 1 | 10 Widget Company | 2 | 2 The reason being that there is also a separate table of users that link to these organizations, and I would like to unify them (therefore remove dupes so the users link to the same organization instead of dupe orgs). But I would like part manually so I don't screw anything up, but I would still need a statement returning the IDs of all the dupe orgs so I can go through the list of users. Any help would be greatly appreciated. Thanks :)

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• Concatenate row values T-SQL

  - by Robert

  I am trying to pull together some data for a report and need to concatenate the row values of one of the tables. Here is the basic table structure: Reviews ReviewID ReviewDate Reviewers ReviewerID ReviewID UserID Users UserID FName LName This is a M:M relationship. Each Review can have many Reviewers; each User can be associated with many Reviews. Basically, all I want to see is Reviews.ReviewID, Reviews.ReviewDate, and a concatenated string of the FName's of all the associated Users for that Review (comma delimited). Instead of: ReviewID---ReviewDate---User 1----------12/1/2009----Bob 1----------12/1/2009----Joe 1----------12/1/2009----Frank 2----------12/9/2009----Sue 2----------12/9/2009----Alice Display this: ReviewID---ReviewDate----Users 1----------12/1/2009-----Bob, Joe, Frank 2----------12/9/2009-----Sue, Alice I have found this article describing some ways to do this, but most of these seem to only deal with one table, not multiple; unfortunately, my SQL-fu is not strong enough to adapt these to my circumstances. I am particularly interested in the example on that site which utilizes FOR XML PATH() as that looks the cleanest and most straight forward. SELECT p1.CategoryId, ( SELECT ProductName + ', ' FROM Northwind.dbo.Products p2 WHERE p2.CategoryId = p1.CategoryId ORDER BY ProductName FOR XML PATH('') ) AS Products FROM Northwind.dbo.Products p1 GROUP BY CategoryId; Can anyone give me a hand with this? Any help would be greatly appreciated!

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• Using LINQ to fetch result from nested SQL queries

  - by Shantanu Gupta

  This is my first question and first day in Linq so bit difficult day for me to understand. I want to fetch some records from database i.e. select * from tblDepartment where department_id in ( select department_id from tblMap where Guest_Id = @GuestId ) I have taken two DataTable. i.e. tblDepartment, tblMap Now I want to fetch this result and want to store it in third DataTable. How can I do this. I have been able to construct this query up till now after googling. var query = from myrow in _dtDepartment.AsEnumerable() where myrow.Field<int>("Department_Id") == _departmentId select myrow; Please provide me some link for learning Linq mainly for DataTables and DataSets. EDIT: I have got a very similar example here but i m still not able to understand how it is working. Please put some torch on it.

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• Tricky SQL query involving consecutive values

  - by Gabriel

  I need to perform a relatively easy to explain but (given my somewhat limited skills) hard to write SQL query. Assume we have a table similar to this one: exam_no | name | surname | result | date ---------+------+---------+--------+------------ 1 | John | Doe | PASS | 2012-01-01 1 | Ryan | Smith | FAIL | 2012-01-02 <-- 1 | Ann | Evans | PASS | 2012-01-03 1 | Mary | Lee | FAIL | 2012-01-04 ... | ... | ... | ... | ... 2 | John | Doe | FAIL | 2012-02-01 <-- 2 | Ryan | Smith | FAIL | 2012-02-02 2 | Ann | Evans | FAIL | 2012-02-03 2 | Mary | Lee | PASS | 2012-02-04 ... | ... | ... | ... | ... 3 | John | Doe | FAIL | 2012-03-01 3 | Ryan | Smith | FAIL | 2012-03-02 3 | Ann | Evans | PASS | 2012-03-03 3 | Mary | Lee | FAIL | 2012-03-04 <-- Note that exam_no and date aren't necessarily related as one might expect from the kind of example I chose. Now, the query that I need to do is as follows: From the latest exam (exam_no = 3) find all the students that have failed (John Doe, Ryan Smith and Mary Lee). For each of these students find the date of the first of the batch of consecutively failing exams. Another way to put it would be: for each of these students find the date of the first failing exam that comes after their last passing exam. (Look at the arrows in the table). The resulting table should be something like this: name | surname | date_since_failing ------+---------+-------------------- John | Doe | 2012-02-01 Ryan | Smith | 2012-01-02 Mary | Lee | 2012-01-04 Ann | Evans | 2012-02-03 How can I perform such a query? Thank you for your time.

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