Search Results

Search found 25852 results on 1035 pages for 'linq query syntax'.

Page 104/1035 | < Previous Page | 100 101 102 103 104 105 106 107 108 109 110 111  | Next Page >

  • MySQL query problem

    - by SaltLake
    I've got MySQL table CREATE TABLE stat ( ID int NOT NULL auto_increment PRIMARY KEY, TIMESTAMP_X timestamp DEFAULT CURRENT_TIMESTAMP, # ... some other fields ... ) which contains statistics about site visitors. For getting visits per hour I use SELECT hour(TIMESTAMP_X) as HOUR , count(*) AS HOUR_STAT FROM cms_webstat GROUP BY HOUR ORDER BY HOUR DESC which gives me | HOUR | HOUR_STAT | | 24 | 15 | | 23 | 12 | | 22 | 9 | | 20 | 3 | | 18 | 2 | | 15 | 1 | | 12 | 3 | | 9 | 1 | | 3 | 5 | | 2 | 7 | | 1 | 9 | | 0 | 12 | And I'd like to get following: | HOUR | HOUR_STAT | | 24 | 15 | | 23 | 12 | | 22 | 9 | | 21 | 0 | | 20 | 3 | | 19 | 0 | | 18 | 2 | | 17 | 0 | | 16 | 0 | | 15 | 1 | | 14 | 0 | | 13 | 0 | | 12 | 3 | | 11 | 0 | | 10 | 0 | | 9 | 1 | | 8 | 0 | | 7 | 0 | | 6 | 0 | | 5 | 0 | | 4 | 0 | | 3 | 5 | | 2 | 7 | | 1 | 9 | | 0 | 12 | How should I modify the query to get such result? Thanks.

    Read the article

  • Need help with some complex SQL query

    - by Psyche
    Hello guys, I need some help with a complex SQL query. Here's my setup: there are two tables, one with authors, and another with books. The books table contains a field named "author" which holds author's id. If a book has more than one author, then the "author" field will contain all the authors ids separated by ";" (something like 2;34;234). On the website I have to list all the books written by an author. If there's only one author, its simple, but how can I get those books where the author I'm interested in is the second or third author? Many thanks.

    Read the article

  • sql query is too slow, how to improve speed

    - by user1289282
    I have run into a bottleneck when trying to update one of my tables. The player table has, among other things, id, skill, school, weight. What I am trying to do is: SELECT id, skill FROM player WHERE player.school = (current school of 4500) AND player.weight = (current weight of 14) to find the highest skill of all players returned from the query UPDATE player SET starter = 'TRUE' WHERE id = (highest skill) move to next weight and repeat when all weights have been completed move to next school and start over all schools completed, done I have this code implemented and it works, but I have approximately 4500 schools totaling 172000 players and the way I have it now, it would take probably a half hour or more to complete (did not wait it out), which is way too slow. How to speed this up? Short of reducing the scale of the system, I am willing to do anything that gets the intended result. Thanks! *the weights are the standard folk style wrestling weights ie, 103, 113, 120, 126, 132, 138, 145, 152, 160, 170, 182, 195, 220, 285 pounds

    Read the article

  • Django query - join on the same table

    - by dana
    i have a mini blog app, and a 'timeline' . there i want to be displayed all the posts from all the friends of a user, plus the posts of that user himself. For that, i have to make some kind of a 'join' between the results of two queries (queries on the same table) , so that the final result will be the combination of the user - posesor of the account, and all his friends. My query looks like this: blog = New.objects.filter(created_by = following,created_by = request.user) By that ',' i wanted to make a 'join' -i found something like this on a doc- but this method is not correct- i'm getting an error. How else could be done this 'join' ? Thanks!

    Read the article

  • Counting multiple rows in MySQL in one query

    - by diggersworld
    I currently have a table which stores a load of statistics such as views, downloads, purchases etc. for a multiple number of items. To get a single operation count on each item I can use the following query: SELECT , COUNT() FROM stats WHERE operation = 'view' GROUP BY item_id This gives me all the items and a count of their views. I can then change 'view' to 'purchase' or 'download' for the other variables. However this means three separate calls to the database. Is it possible to get all three in one go?

    Read the article

  • Update query (access & vb.net)

    - by yae
    Hi: I have to update some fields of a table of access according to the value of parameter. If this paramter is "true" I need to update. Table idInvoice price percentageTax1 tax1 percentageTax2 tax2 total Example values: idinvoice: 12300 price: 100 € percentageTax1: 10 % tax1= 10€ percentageTax2: 5 % tax2: 5€ total: 115 € (result: 100€+10€+5€) Ok. If the parameter on that I have commented before is "true" I must update the percentages and then update the total. I need to replace the "old" percentages by new percent. Ok I can do it in 3 queries: update invocies set percentageTax1=20,tax1=price *(percentageTax1/100) where idInvoice=@number and percentageTax1=10 update invocies set percentageTax2=7,tax2=price *(percentageTax2/100) where idInvoice=@number and percentageTax2=5 update invocies set total=price+tax1+tax2 where idInvoice=@number . But my question is: is there any an alternative to do this in 1 query?

    Read the article

  • [SQL][MS access] Query to find duplicate item in 2 table

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

    Read the article

  • Entity Framework 4.0: Optimal and horrible SQL

    - by DigiMortal
    Lately I had Entity Framework 4.0 session where I introduced new features of Entity Framework. During session I found out with audience how Entity Framework 4.0 can generate optimized SQL. After session I also showed guys one horrible example about how awful SQL can be generated by Entity Framework. In this posting I will cover both examples. Optimal SQL Before going to code take a look at following model. There is class called Event and I will use this class in my query. Here is the LINQ To Entities query that uses small anonymous type. var query = from e in _context.Events             select new { Id = e.Id, Title = e.Title }; Debug.WriteLine(((ObjectQuery)query).ToTraceString()); Running this code gives us the following SQL. SELECT      [Extent1].[event_id] AS [event_id],      [Extent1].[title] AS [title]  FROM [dbo].[events] AS [Extent1] This is really small – no additional fields in SELECT clause. Nice, isn’t it? Horrible SQL Ayende Rahien blog shows us darker side of Entiry Framework 4.0 queries. You can find comparison betwenn NHibernate, LINQ To SQL and LINQ To Entities from posting What happens behind the scenes: NHibernate, Linq to SQL, Entity Framework scenario analysis. In this posting I will show you the resulting query and let you think how much better it can be done. Well, it is not something we want to see running in our servers. I hope that EF team improves generated SQL to acceptable level before Visual Studio 2010 is released. There is also morale of this example: you should always check out the queries that O/R-mapper generates. Behind the curtains it may silently generate queries that perform badly and in this case you need to optimize you data querying strategy. Conclusion Entity Framework 4.0 is new product with a lot of new features and it is clear that not everything is 100% super in its first release. But it still great step forward and I hope that on 12.04.2010 we have new promising O/R-mapper available to use in our projects. If you want to read more about Entity Framework 4.0 and Visual Studio 2010 then please feel free to follow this link to list of my Visual Studio 2010 and .NET Framework 4.0 postings.

    Read the article

  • Getting the first result from a LINQ query - why does ElementAt<T>(0) fails when First<T>() succeeds

    - by Mr Roys
    I have a method AddStudent() which looks for a student with the same name and returns an existing student from the database if there is a student with the same name, otherwise it creates a new student and adds it to the database. I'm curious why se = students.First<StudentEntity>(); succeeds when se = students.ElementAt<StudentEntity>(0); fails when I try to get the first result from the LINQ query. Aren't the two methods the same? The full code for the method is shown below. public Student AddStudent(string name) { using (SchoolEntities db = new SchoolEntities()) { // find student with same name via LINQ var students = from s in db.StudentEntitySet where s.name == name select s; StudentEntity se = default(StudentEntity); // if student with the same name is already present, return // that student if (students.Count<StudentEntity>() > 0) { // if i use ElementAt, if fails with a "LINQ to Entities does not // recognize the method 'StudentEntity ElementAt[StudentEntity] // (System.Linq.IQueryable`1[StudentEntity], Int32)' method, // and this method cannot be translated into a store expression.", // but not when I use First. Why? // se = students.ElementAt<StudentEntity>(0); se = students.First<StudentEntity>(); } else { // passing 0 for first parameter (id) since it's represented by // a BigInt IDENTITY field in the database so any value // doesn't matter. se = StudentEntity.CreateStudentEntity(0, name); db.AddToStudentEntitySet(se); db.SaveChanges(); } // create a Student object from the Entity object return new Student(se); } } Thanks!

    Read the article

  • How to use different providers for Linq to entities?

    - by Anders Svensson
    I'm trying to familiarize myself a bit more with database programming, and I'm looking at different ways of creating a data access layer for applications. I've tried out a few ways but there is such a jungle of different database technologies that I don't know what to learn. For instance I've tried using datasets with tableadapters. Using that I am able to switch data provider rather easily (by programming against the interfaces such as IDbConnection). This is one thing I would want to achieve. But I also know everyone's talking about LINQ, and I'm trying to get to know that a bit better too. So I have tried using Linq to Sql classes as the data access layer as well, but apparently this is not provider independent (works only for SQL Server). So then I read about the Entity Framework (which just as Linq to SQL apparently has gotten its share of bashing already...). It's supposed to be provider independent everybody says, but how? I tried out a tutorial to create an entity data model, but the only providers to choose from were SQL Server/Express. Just for learning purposes, I would like to know how to use the entity framework with MS Access/OleDb. Also, I would appreciate some input on what is the preferred database technology for data access. Is it LINQ still after all the bashing, or should you just use datasets because they are provider independent? Any pointers for what to learn would be great, because it's just too much to learn it all if I'm not going to use it in the end...!

    Read the article

  • SQL SERVER – Subquery or Join – Various Options – SQL Server Engine knows the Best

    - by pinaldave
    This is followup post of my earlier article SQL SERVER – Convert IN to EXISTS – Performance Talk, after reading all the comments I have received I felt that I could write more on the same subject to clear few things out. First let us run following four queries, all of them are giving exactly same resultset. USE AdventureWorks GO -- use of = SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID = ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA WHERE EA.EmployeeID = E.EmployeeID) GO -- use of in SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID IN ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA WHERE EA.EmployeeID = E.EmployeeID) GO -- use of exists SELECT * FROM HumanResources.Employee E WHERE EXISTS ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA WHERE EA.EmployeeID = E.EmployeeID) GO -- Use of Join SELECT * FROM HumanResources.Employee E INNER JOIN HumanResources.EmployeeAddress EA ON E.EmployeeID = EA.EmployeeID GO Let us compare the execution plan of the queries listed above. Click on image to see larger image. It is quite clear from the execution plan that in case of IN, EXISTS and JOIN SQL Server Engines is smart enough to figure out what is the best optimal plan of Merge Join for the same query and execute the same. However, in the case of use of Equal (=) Operator, SQL Server is forced to use Nested Loop and test each result of the inner query and compare to outer query, leading to cut the performance. Please note that here I no mean suggesting that Nested Loop is bad or Merge Join is better. This can very well vary on your machine and amount of resources available on your computer. When I see Equal (=) operator used in query like above, I usually recommend to see if user can use IN or EXISTS or JOIN. As I said, this can very much vary on different system. What is your take in above query? I believe SQL Server Engines is usually pretty smart to figure out what is ideal execution plan and use it. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • SQL SERVER – Subquery or Join – Various Options – SQL Server Engine Knows the Best – Part 2

    - by pinaldave
    This blog post is part 2 of the earlier written article SQL SERVER – Subquery or Join – Various Options – SQL Server Engine knows the Best by Paulo R. Pereira. Paulo has left excellent comment to earlier article once again proving the point that SQL Server Engine is smart enough to figure out the best plan itself and uses the same for the query. Let us go over his comment as he has posted. “I think IN or EXISTS is the best choice, because there is a little difference between ‘Merge Join’ of query with JOIN (Inner Join) and the others options (Left Semi Join), and JOIN can give more results than IN or EXISTS if the relationship is 1:0..N and not 1:0..1. And if I try use NOT IN and NOT EXISTS the query plan is different from LEFT JOIN too (Left Anti Semi Join vs. Left Outer Join + Filter). So, I found a case where EXISTS has a different query plan than IN or ANY/SOME:” USE AdventureWorks GO -- use of SOME SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID = SOME ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA UNION ALL SELECT EA.EmployeeID FROM HumanResources.EmployeeDepartmentHistory EA ) -- use of IN SELECT * FROM HumanResources.Employee E WHERE E.EmployeeID IN ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA UNION ALL SELECT EA.EmployeeID FROM HumanResources.EmployeeDepartmentHistory EA ) -- use of EXISTS SELECT * FROM HumanResources.Employee E WHERE EXISTS ( SELECT EA.EmployeeID FROM HumanResources.EmployeeAddress EA UNION ALL SELECT EA.EmployeeID FROM HumanResources.EmployeeDepartmentHistory EA ) When looked into execution plan of the queries listed above indeed we do get different plans for queries and SQL Server Engines creates the best (least cost) plan for each query. Click on image to see larger images. Thanks Paulo for your wonderful contribution. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Contribution, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • Twitter User/Search Feature Header Support in LINQ to Twitter

    - by Joe Mayo
    LINQ to Twitter’s goal is to support the entire Twitter API. So, if you see a new feature pop-up, it will be in-queue for inclusion. The same holds for the new X-Feature… response headers for User/Search requests.  However, you don’t have to wait for a special property on the TwitterContext to access these headers, you can just use them via the TwitterContext.ResponseHeaders collection. The following code demonstrates how to access the new X-Feature… headers with LINQ to Twitter: var user = (from usr in twitterCtx.User where usr.Type == UserType.Search && usr.Query == "Joe Mayo" select usr) .FirstOrDefault(); Console.WriteLine( "X-FeatureRateLimit-Limit: {0}\n" + "X-FeatureRateLimit-Remaining: {1}\n" + "X-FeatureRateLimit-Reset: {2}\n" + "X-FeatureRateLimit-Class: {3}\n", twitterCtx.ResponseHeaders["X-FeatureRateLimit-Limit"], twitterCtx.ResponseHeaders["X-FeatureRateLimit-Remaining"], twitterCtx.ResponseHeaders["X-FeatureRateLimit-Reset"], twitterCtx.ResponseHeaders["X-FeatureRateLimit-Class"]); The query above is from the User entity, whose type is Search; allowing you to search for the Twitter user whose name is specified by the Query parameter filter. After materializing the query, with FirstOrDefault, twitterCtx will hold all of the headers, including X-Feature… that Twitter returned.  Running the code above will display results similar to the following: X-FeatureRateLimit-Limit: 60 X-FeatureRateLimit-Remaining: 59 X-FeatureRateLimit-Reset: 1271452177 X-FeatureRateLimit-Class: namesearch In addition to getting the X-Feature… headers a capability you might have noticed is that the TwitterContext.ResponseHeaders collection will contain any HTTP that Twitter sends back to a query. Therefore, you’ll be able to access new Twitter headers anytime in the future with LINQ to Twitter. @JoeMayo

    Read the article

  • Modify Wordpress SQL Query to pull from within a category

    - by Levi
    Hi I am using a wordpress plugin called "kf most read" which stores a count of how many times a post was read, and lets you output a list of most read posts. This works well. The issue is, I am trying to pull the most read posts, but only the most read posts within the current category you are viewing. I am close to clueless when it comes to sql. Here us what the plugin is currently using to pull the most read posts: $sql = "SELECT count(mr.post_ID) as totHits, p.ID, p.post_title from $wpdb-posts p JOIN {$wpdb-prefix}kf_most_read mr on mr.post_ID = p.ID where mr.hit_ts = '".(time() - ( 86400 * $period))."' GROUP BY mr.post_ID order by totHits desc, ID ASC LIMIT $limit"; How could I incorporate the below query which pulls from a specific category into the above? $sql .= "LEFT JOIN $wpdb-term_taxonomy ON($wpdb-term_relationships.term_taxonomy_id = $wpdb-term_taxonomy.term_taxonomy_id)" ; $sql .= "WHERE $wpdb-term_taxonomy.term_id IN ($currentcat)" ; $sql .= "AND $wpdb-term_taxonomy.taxonomy = 'category'" ; Any Help on this would be much appreciated.

    Read the article

  • Oracle Text query parser

    - by Roger Ford
    Oracle Text provides a rich query syntax which enables powerful text searches.However, this syntax isn't intended for use by inexperienced end-users.  If you provide a simple search box in your application, you probably want users to be able to type "Google-like" searches into the box, and have your application convert that into something that Oracle Text understands.For example if your user types "windows nt networking" then you probably want to convert this into something like"windows ACCUM nt ACCUM networking".  But beware - "NT" is a reserved word, and needs to be escaped.  So let's escape all words:"{windows} ACCUM {nt} ACCUM {networking}".  That's fine - until you start introducing wild cards. Then you must escape only non-wildcarded searches:"win% ACCUM {nt} ACCUM {networking}".  There are quite a few other "gotchas" that you might encounter along the way.Then there's the issue of scoring.  Given a query for "oracle text query syntax", it would be nice if we could score a full phrase match higher than a hit where all four words are present but not in a phrase.  And then perhaps lower than that would be a document where three of the four terms are present.  Progressive relaxation helps you with this, but you need to code the "progression" yourself in most cases.To help with this, I've developed a query parser which will take queries in Google-like syntax, and convert them into Oracle Text queries. It's designed to be as flexible as possible, and will generate either simple queries or progressive relaxation queries. The input string will typically just be a string of words, such as "oracle text query syntax" but the grammar does allow for more complex expressions:  word : score will be improved if word exists  +word : word must exist  -word : word CANNOT exist  "phrase words" : words treated as phrase (may be preceded by + or -)  field:(expression) : find expression (which allows +,- and phrase as above) within "field". So for example if I searched for   +"oracle text" query +syntax -ctxcatThen the results would have to contain the phrase "oracle text" and the word syntax. Any documents mentioning ctxcat would be excluded from the results. All the instructions are in the top of the file (see "Downloads" at the bottom of this blog entry).  Please download the file, read the instructions, then try it out by running "parser.pls" in either SQL*Plus or SQL Developer.I am also uploading a test file "test.sql". You can run this and/or modify it to run your own tests or run against your own text index. test.sql is designed to be run from SQL*Plus and may not produce useful output in SQL Developer (or it may, I haven't tried it).I'm putting the code up here for testing and comments. I don't consider it "production ready" at this point, but would welcome feedback.  I'm particularly interested in comments such as "The instructions are unclear - I couldn't figure out how to do XXX" "It didn't work in my environment" (please provide as many details as possible) "We can't use it in our application" (why not?) "It needs to support XXX feature" "It produced an invalid query output when I fed in XXXX" Downloads: parser.pls test.sql

    Read the article

  • Slow MySQL Query Breaking my back!

    - by Chris n
    so, I have tried everything I can think of, and can't get this query to happen in less than 3 seconds on my local server. I know the problem has to do with the OR referencing both the owner_id and the person_id. if I run one or the other it happens instantly, but together with an or I can't seem to make it work - I looked into rewriting the code, but the way the app was designed it won't be easy. is there a way I can call an equivalent or that won't take so long? here is the sql: SELECT event_types.name as event_type_name,event_types.id as id, count(events.id) as count,sum(events.estimated_duration) as time_sum FROM events,event_types WHERE event_types.id = events.event_type_id AND events.event_type_id != '4' AND ( events.status!='cancelled') AND events.event_type_id != 64 AND ( events.owner_id = 161 OR events.person_id = 161 ) GROUP BY event_types.name ORDER BY event_types.name DESC; Here's the Explain soup, although I'm guessing it's unnecessary cause there is probably a better way to structure that or that is obvious: thanks so much! chris. +----+-------------+-------------+-------+---------------------------------------------------------------------------------------------------------+-------------------------------+---------+-------------------------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------+-------+---------------------------------------------------------------------------------------------------------+-------------------------------+-- | 1 | SIMPLE | event_types | range | PRIMARY | PRIMARY | 4 | NULL | 78 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | events | ref | index_events_on_status,index_events_on_event_type_id,index_events_on_person_id,index_events_on_owner_id | index_events_on_event_type_id | 5 | thenumber_production.event_types.id | 907 | Using where | +----+-------------+-------------+-------+---------------------------------------------------------------------------------------------------------+-------------------------------+---------+-------------------------------------+------+----------------------------------------------+

    Read the article

  • Help with MySQL query - Product orders report without duplicate shipping charges

    - by Paul
    Hello, I have an issue creating a custom report for an e-commerce store running on osCommerce. The client wants the report to have the following columns: Date, Order ID, Product Class, Product Price, Product Tax, Shipping, Order Total The criteria for generating the report are Date Range and Product Class (Textbooks for example) The client wants the report to list each Textbook purchased on its own line. Orders with multiple textbooks would display a separate line for each Textbook in the order. I have it all working except for one part: the shipping amount is order-specific (based on the order total), not product-specific, and is displaying for each product. I need it to display only for the first product of each order, so it is not counted more than once. My current query is: SELECT op.date_funds_captured as 'Date', op.orders_id as 'Order ID', pc.class as 'Product Class', round(op.products_price,2) as 'Product Price', round(op.products_tax*op.products_price/100,2) as 'Product Tax', round(otship.value,2) as 'Shipping', round(ot.value,2) as 'Order Total' from orders_products op, orders_total ot, orders_total otship, productclasses pc, products p where ot.orders_id = op.orders_id and ot.class='ot_total' and op.orders_id = otship.orders_id and otship.class = 'ot_shipping' and p.products_class_id = pc.id and op.products_id = p.products_id and pc.id = 1 pc.id = 1 -- Product class = Textbook Here is an example of the current report output. You can see the problem with order 2256 showing the shipping value three times instead of once: Date Order Product Class Price Tax Shipping Total 2010-01-04 2253 Textbook 24.95 2.43 10.03 37.41 2010-01-04 2256 Textbook 34.95 0.00 18.09 240.37 2010-01-04 2256 Textbook 55.50 0.00 18.09 240.37 2010-01-04 2256 Textbook 36.95 0.00 18.09 240.37 2010-01-04 2258 Textbook 55.50 5.41 12.17 124.24 Please help!!! Thanks, Paul

    Read the article

  • Command-Query-Separation and multithreading safe interfaces

    - by Tobias Langner
    I like the command query separation pattern (from OOSC / Eiffel - basically you either return a value or you change the state of the class - but not both). This makes reasoning about the class easier and it is easier to write exception safe classes. Now, with multi threading, I run into a major problem: the separation of the query and the command basically invalidates the result from the query as anything can happen between those 2. So my question is: how do you handle command query separation in an multi-threaded environment? Clarification example: A stack with command query separation would have the following methods: push (command) pop (command - but does not return a value) top (query - returns the value) empty (query) The problem here is - I can get empty as status, but then I can not rely on top really retrieving an element since between the call of empty and the call of top, the stack might have been emptied. Same goes for pop & top. If I get an item using top, I can not be sure that the item that I pop is the same. This can be solved using external locks - but that's not exactly what I call threadsafe design.

    Read the article

  • How to query collections in NHibernate

    - by user305813
    Hi, I have a class: public class User { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual IDictionary<string, string> Attributes { get; set; } } and a mapping file: <class name="User" table="Users"> <id name="Id"> <generator class="hilo"/> </id> <property name="Name"/> <map name="Attributes" table="UserAttributes"> <key column="UserId"/> <index column="AttributeName" type="System.String"/> <element column="Attributevalue" type="System.String"/> </map> </class> So now I can add many attributes and values to a User. How can I query those attributes so I can get ie. Get all the users where attributename is "Age" and attribute value is "20" ? I don't want to do this in foreach because I may have millions of users each having its unique attributes. Please help

    Read the article

  • conditional update records mysql query

    - by Shakti Singh
    Hi, Is there any single msql query which can update customer DOB? I want to update the DOB of those customers which have DOB greater than current date. example:- if a customer have dob 2034 update it to 1934 , if have 2068 updated with 1968. There was a bug in my system if you enter date less than 1970 it was storing it as 2070. The bug is solved now but what about the customers which have wrong DOB. So I have to update their DOB. All customers are stored in customer_entity table and the entity_id is the customer_id Details is as follows:- desc customer_entity -> ; +------------------+----------------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------------+----------------------+------+-----+---------------------+----------------+ | entity_id | int(10) unsigned | NO | PRI | NULL | auto_increment | | entity_type_id | smallint(8) unsigned | NO | MUL | 0 | | | attribute_set_id | smallint(5) unsigned | NO | | 0 | | | website_id | smallint(5) unsigned | YES | MUL | NULL | | | email | varchar(255) | NO | MUL | | | | group_id | smallint(3) unsigned | NO | | 0 | | | increment_id | varchar(50) | NO | | | | | store_id | smallint(5) unsigned | YES | MUL | 0 | | | created_at | datetime | NO | | 0000-00-00 00:00:00 | | | updated_at | datetime | NO | | 0000-00-00 00:00:00 | | | is_active | tinyint(1) unsigned | NO | | 1 | | +------------------+----------------------+------+-----+---------------------+----------------+ 11 rows in set (0.00 sec) And the DOB is stored in the customer_entity_datetime table the column value contain the DOB. but in this table values of all other attribute are also stored such as fname,lname etc. So the attribute_id with value 11 is DOB attribute. mysql> desc customer_entity_datetime; +----------------+----------------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------------+----------------------+------+-----+---------------------+----------------+ | value_id | int(11) | NO | PRI | NULL | auto_increment | | entity_type_id | smallint(8) unsigned | NO | MUL | 0 | | | attribute_id | smallint(5) unsigned | NO | MUL | 0 | | | entity_id | int(10) unsigned | NO | MUL | 0 | | | value | datetime | NO | | 0000-00-00 00:00:00 | | +----------------+----------------------+------+-----+---------------------+----------------+ 5 rows in set (0.01 sec) Thanks.

    Read the article

  • Query Access and VB.NET

    - by yae
    Hi all: I have 2 tables: "products" and "pieces" PRODUCTS idProd product price PIECES id idProdMain idProdChild quant idProdMain and idProdChild are vinculated with the table: "products". Other considerations is that 1 product can have some pieces and 1 product can be a piece. Price product equal a sum of quantity * price of all their pieces. EXAMPLE: TABLE PRODUCTS (idProd - product - price) 1 - Computer - 300€ 2 - Hard Disk - 100€ 3 - Memory - 50€ 4 - Main Board - 100€ 5 - Software - 50€ 6 - CDroms 100 un. - 30€ TABLE PIECES (id - idProdMain - idProdChild - Quant.) 1 - 1 - 2 - 1 2 - 1 - 3 - 2 3 - 1 - 4 - 1 WHAT I NEED? I need update the price of the main product when the price of the product child (piece) is changed. Following the previous example, if I change the price of this product "memory" (is a piece too) to 60€, then product "Computer" will must change his price to 320€ How I can do it using queries? Already I have tried this to obatin the price of the main product, but not runs. This query not returns any value SELECT Sum(products.price*pieces.quant) AS Expr1 FROM products LEFT JOIN pieces ON (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdMain) WHERE (((pieces.idProdMain)=5));

    Read the article

  • SQL Query with multiple values in one column

    - by lp1
    I've been beating my head on the desk tring to figure this one out. I have a table that stores job information, and reasons for a job not being completed. The reasons are numeric,01,02,03,etc. You can have two reason for a pending job. If you select two reasons, they are stored in the same column, seperated by a comma. This is anExample from the JOBID table: Job_Number User_Assigned PendingInfo 1 user1 01,02 Now, there is another table named Pending, that stores what those values actually represent. 01=Not enough info, 02=Not enough time, 03=Waiting Review. Example: Pending_Num PendingWord 01 Not Enough Info 02 Not Enough Time What I'm trying to do is query the database to give me all the job numbers, users, pendinginfo, and pending reason. I can break out the first value, but can't figure out how to do the second. What my limited skills have so far: *select Job_number,user_assigned,SUBSTRING(pendinginfo,0,3),pendingword from jobid,pending where SUBSTRING(pendinginfo,0,3)=pending.pending_num and pendinginfo!='00,00' and pendinginfo!='NULL'* What I would like to see for this example would be: Job_Number User_Assigned PendingInfo PendingWord PendingInfo PendingWord 1 User1 01 Not Enough Info 02 Not Enough Time Thanks in advance

    Read the article

  • Help Me With This Access Query

    - by yae
    I have 2 tables: "products" and "pieces" PRODUCTS idProd product price PIECES id idProdMain idProdChild quant idProdMain and idProdChild are related with the table: "products". Other considerations is that 1 product can have some pieces and 1 product can be a piece. Price product equal a sum of quantity * price of all their pieces. "Products" table contains all products (p EXAMPLE: TABLE PRODUCTS (idProd - product - price) 1 - Computer - 300€ 2 - Hard Disk - 100€ 3 - Memory - 50€ 4 - Main Board - 100€ 5 - Software - 50€ 6 - CDroms 100 un. - 30€ TABLE PIECES (id - idProdMain - idProdChild - Quant.) 1 - 1 - 2 - 1 2 - 1 - 3 - 2 3 - 1 - 4 - 1 WHAT I NEED? I need update the price of the main product when the price of the product child (piece) is changed. Following the previous example, if I change the price of this product "memory" (is a piece too) to 60€, then product "Computer" will must change his price to 320€ How I can do it using queries? Already I have tried this to obatin the price of the main product, but not runs. This query not returns any value: SELECT Sum(products.price*pieces.quant) AS Expr1 FROM products LEFT JOIN pieces ON (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdMain) WHERE (((pieces.idProdMain)=5)); MORE INFO The table "products" contains all the products to sell that it is in the shop. The table "pieces" is to take a control of the compound products. To know those who are the products children. For example of compound product: computers. This product is composed by other products (motherboard, hard disk, memory, cpu, etc.)

    Read the article

  • XPATH Query: How to get two elements?

    - by Damiano
    Hello My HTML code is: <table> <tr> <td class="data1"><p>1</td></td> <td class="data1"><p>2</td></td> <td class="data1"><p>3</td></td> <td class="data1"><p>4</td></td> </tr> <tr> <td class="data1"><p>5</td></td> <td class="data1"><p>6</td></td> <td class="data1"><p>7</td></td> <td class="data1"><p>8</td></td> </tr> </table> My query is: xpath='//tr//td[@class="data1"][4]/p' The results is: <p>4</p> <p>8</p> The results is correct! but, if I want to get example: <p>3</p> <p>4</p> <p>7</p> <p>8</p> So [3]/p and [4]/p How to get these two elements each <tr> ? Thank you so much!

    Read the article

< Previous Page | 100 101 102 103 104 105 106 107 108 109 110 111  | Next Page >