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  • Can I bypass an intermediate object in hibernate

    - by Jherico
    I have top level entities TRACK, MEDIA_GROUP and MEDIA, each with an integer primary key. I also have a join table from TRACK to MEDIA_GROUP which is 1:1 and MEDIA has a FK column into MEDIA_GROUP. I'm trying to find a way in hibernate to map a collection of Media directly into the Track object, bypassing the creation of a MediaGroup object. Basically I want to turn this: TRACK <-> MEDIA_TRACK_MAP <-> MEDIA_GROUP <-> MEDIA into this: TRACK <-> MEDIA_TRACK_MAP <-> MEDIA But the join column between MEDIA_TRACK_MAP and MEDIA isn't the primary key of MEDIA.

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  • Write a SQL Query to replace values and include all the Dates.

    - by VJ
    Well I have this - Table DimDate- Date Table Employee- Id,Name,Points,Date Now the Employee table has points for everyday unless they did not come...so the Date does not have all the Dates entries... I mean for e.g in a week he did not come for 2 days the Employee table has only 5 rows...so I have this dimdate table which has all the dates till 2050 which I want to join with and add Zeros for the dates he does not have points. So I have written this query but does not work - Select E.EmployeeId,D.Date,isNull(E.Points,0) from DimDate D left join Employee E on D.Date between '01-01-2009'and '06-01-2009' where E.EmployeeId=1 The above query give multiple dates and I tried group by on Date but does not work.

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  • [SQL] Query returning more than one row with the same name

    - by Neutralise
    I am having trouble with an SQL query returning more than one row with the same name, using this query: SELECT * FROM People P JOIN SpecialityCombo C ON P.PERSONID = C.PERSONID JOIN Speciality S ON C.GROUPID = S.ID; People contains information on each person, Specialty contains the names and ID of each specialty and SpecialityCombo contains information about the associations between People and their Speciality, namely each row has a PERSONID and a Speciality ID (trying to keep it normalised to some extent). My query works in that it returns each Person and the name of their specialty, but it returns n rows for the number of specialitys they want, because each specialty returns the same row 'name'. What I want is it to return just one row containing each speciality. How can I do this?

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  • Problem with joining to an empty table

    - by Imran Omar Bukhsh
    I use the following query: select * from A LEFT JOIN B on ( A.t_id != B.t_id) to get all the records in A that are not in B. The results are fine except when table B is completely empty, but then I do not get any records, even from table A. Later It wont work yet! CREATE TABLE IF NOT EXISTS T1 ( id int(11) unsigned NOT NULL AUTO_INCREMENT, title varchar(50) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL, t_id int(11) NOT NULL, PRIMARY KEY (id) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -- Dumping data for table T1 INSERT INTO T1 (id, title, t_id) VALUES (1, 'apple', 1), (2, 'orange', 2); -- -- Table structure for table T2 CREATE TABLE IF NOT EXISTS T2 ( id int(11) NOT NULL AUTO_INCREMENT, title varchar(50) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL, t_id int(11) NOT NULL, PRIMARY KEY (id) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; -- -- Dumping data for table T2 INSERT INTO T2 (id, title, t_id) VALUES (1, 'dad', 2); Now I want to get all records in T1 that do not have a corresponding records in T2 I try SELECT * FROM T1 LEFT OUTER JOIN T2 ON T1.t_id != T2.t_id and it won't work

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  • Return multiple results using dynamic sql (postgresql 8.2)

    - by precose
    I want to loop through schemas and get a result set that looks like this: Count 5 834 345 34 984 However, I can't get it to return anything using dynamic sql...I've tried everything but 8.2 is being a real pain. Here is my function: CREATE OR REPLACE FUNCTION dwh.adam_test4() RETURNS void LANGUAGE plpgsql AS $function$ DECLARE myschema text; rec RECORD; BEGIN FOR myschema IN select distinct c.table_schema, d.p_id from information_schema.tables t inner join information_schema.columns c on (t.table_schema = t.table_schema and t.table_name = c.table_name) join dwh.sgmt_clients d on c.table_schema = lower(d.userid) where c.table_name = 'fact_members' and c.column_name = 'debit_card' and t.table_schema NOT LIKE 'pg_%' and t.table_schema NOT IN ('information_schema', 'ad_delivery', 'dwh', 'users', 'wand', 'ttd') order by table_schema LOOP EXECUTE 'select count(ucic) from '|| myschema || '.' ||'fact_members where debit_card = ''yes''' into rec; RETURN rec; END LOOP; END $function$

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  • MySQL GROUP BY with three tables

    - by Psaniko
    I have the following tables: posts (post_id, content, etc) comments (comment_id, post_id, content, etc) posts_categories (post_category_id, post_id, category_id) and this query: SELECT `p`.*, COUNT(comments.comment_id) AS cmts, posts_categories.*,comments.* FROM `posts` AS `p` LEFT JOIN `posts_categories` ON `p`.post_id = `posts_categories`.post_id LEFT JOIN `comments` ON `p`.post_id = `comments`.post_id GROUP BY `p`.`post_id` There are three comments on post_id=1 and four in total. In posts_categories there are two rows, both assigned to post_id=1. I have four rows in posts. But if I query the statement above I get a result of 6 for COUNT(comments.comment_id) at post_id=1. How is this possible? I guess the mistake is somewhere in the GROUP BY clause but I can't figure out where. Any suggestions?

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  • Problem with multi-table MySQL query

    - by mahle
    I have 3 tables. Here is the relevant information needed for each. items prod_id order_id item_qty orders order_id order_date order_status acct_id accounts acct_id is_wholesale items is linked to order by the order_id and orders is linked to accounts via acct_id I need to sum item_qty for all items where prod_id=464 and the order stats is not 5 and where the is_wholesale is 0 and the order_date is between two dates. Im struggling with this and would appreciate any help. Here is what I have but it's not working correctly: SELECT SUM(items.item_qty) as qty FROM items LEFT JOIN orders ON orders.order_id = items.order_id LEFT JOIN accounts on orders.acct_id = accounts.acct_id WHERE items.prod_id =451 AND orders.order_date >= '$from_date' AND orders.order_date <= '$to_date' AND orders.order_status <>5 AND accounts.is_wholesale=0; Again, any help would be greatly appreciated!

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  • wanted to get all dates in mysql result

    - by PankajK
    I have mysql table called user(id, name, join_on) join on is a date field what I want is to show in each day how many uses has been created I can use group by but it will only give me the dates when users get added like if date 4/12/10 5 users added 4/13/10 2 users added 4/15/10 7 users added here date 4/14/10 is missing and I want listing of all dates in one month. I have one solution for it by creating another table only for adding date and that table will left join my users table on join_on and will give total result but I don't want to do that as for creating that I need to create and add entries in date table please suggest the different approach for doing so. Thank you.

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  • Not sure how to use Decode, NVL, and/or isNull (or something else?) in this situation

    - by RSW
    I have a table of orders for particular products, and a table of products that are on sale. (It's not ideal database structure, but that's out of my control.) What I want to do is outer join the order table to the sale table via product number, but I don't want to include any particular data from the sale table, I just want a Y if the join exists or N if it doesn't in the output. Can anyone explain how I can do this in SQL? Thanks in advance!

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  • How to select random image of specific size using Django / Python?

    - by Jonathan
    I've been using this little snippet to select random images. However I would like to change it to select only images of a certain size. I'm running into trouble checking against image size. If I use get_image_dimensions() I need to use a conditional statement, which then requires that I allow exceptions. So, I guess I need some pointers on just limiting by image dimensions. Thanks. import os import random import posixpath from django import template from django.conf import settings register = template.Library() def is_image_file(filename): """Does `filename` appear to be an image file?""" img_types = [".jpg", ".jpeg", ".png", ".gif"] ext = os.path.splitext(filename)[1] return ext in img_types @register.simple_tag def random_image(path): """ Select a random image file from the provided directory and return its href. `path` should be relative to MEDIA_ROOT. Usage: <img src='{% random_image "images/whatever/" %}'> """ fullpath = os.path.join(settings.MEDIA_ROOT, path) filenames = [f for f in os.listdir(fullpath) if is_image_file(f)] pick = random.choice(filenames) return posixpath.join(settings.MEDIA_URL, path, pick)

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  • How to map one class against multiple tables with SQLAlchemy?

    - by tote
    Lets say that I have a database structure with three tables that look like this: items - item_id - item_handle attributes - attribute_id - attribute_name item_attributes - item_attribute_id - item_id - attribute_id - attribute_value I would like to be able to do this in SQLAlchemy: item = Item('item1') item.foo = 'bar' session.add(item) session.commit() item1 = session.query(Item).filter_by(handle='item1').one() print item1.foo # => 'bar' I'm new to SQLAlchemy and I found this in the documentation (http://www.sqlalchemy.org/docs/05/mappers.html#mapping-a-class-against-multiple-tables): j = join(items, item_attributes, items.c.item_id == item_attributes.c.item_id). \ join(attributes, item_attributes.c.attribute_id == attributes.c.attribute_id) mapper(Item, j, properties={ 'item_id': [items.c.item_id, item_attributes.c.item_id], 'attribute_id': [item_attributes.c.attribute_id, attributes.c.attribute_id], }) It only adds item_id and attribute_id to Item and its not possible to add attributes to Item object. Is what I'm trying to achieve possible with SQLAlchemy? Is there a better way to structure the database to get the same behaviour of "dynamic columns"?

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  • AS or not to AS, queries

    - by zeMinimalist
    I'm fairly new to PHP/MySql and using queries in general. I was just wondering if there's any benefit to using "AS" in a query other than trying to make it look cleaner? Does it speed up the query at all? I probably could have figured this out by a google search but I wanted to ask my first question and see how this works. I WILL select an answer (unlike some people...) with: SELECT news.id as id news.name as name FROM news without: SELECT news.id news.name FROM news A more complex example from a many-to-many relationship tutorial I found: SELECT c.name, cf.title FROM celebrities AS c JOIN ( SELECT icf.c_id, icf.f_id, f.title FROM int_cf AS icf JOIN films AS f ON icf.f_id = f.f_id ) AS cf ON c.c_id = cf.c_id ORDER BY c.c_id ASC

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  • Criteria: search for two different entity classes...

    - by RoCMe
    Hi! I have a "super entity" SuperEntity and three entities ChildEntity1, ..., ChildEntity3 which extends the super class. It's easy to search for all entities in the database, i.e. we could use session.createCriteria(SuperEntity.class); It's no problem to search for one specific entity type, too, just replace the SuperEntity with any of the children to look for entities of that type. But I have a problem when allowing 'multiple choice' for the types. I.e., it could be neccessary to search all entities of type 1 and 2, but not of type 3. A first idea was to create two independent queries and join the results in a final list - but that would destroy the paging which uses offset and limit functionality of the database... Is there a possibility in Criteria to join two different queries in one single result list? Kind regards, RoCMe

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  • issue with selecting 1 or 0 in mysql db

    - by jason
    I am having trouble with the following SQL statement i have had this issue before but I cant remember how i fixed the problem, I am guessing the issue with this is that mysql sees 0 as null ? Note I didnt show the first part of the Select statement as its irrelevant my sql works, its showing rows with toffline that are = to 1 as well as 0... FROM table1 AS tb1 LEFT JOIN table2 AS tb2 ON tb2.id = tb1.id2 LEFT JOIN table3 AS tb3 ON tb3.id = tb1.id3 AND tb1.toffline = 0 I have also tried AND NOT tb1.toffline = 1 also WHERE tb1.toffline = 0 all with the same result...

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  • Select products with users

    - by Ploppe
    I have not worked with SQL for quite a long time, and I need some help for a basic query. I have the three following tables: users (id, name) products (id, name) owners (userid, productid, date) One product can be sold by user A to user B and then back to A. Now, I want the list of all products currently owned by every single user with the date of transaction. Currently, my query is this one, but I'm stuck with old data (first association of one product to one user, and not the newest one): SELECT users.name, products.name, date FROM products JOIN owners ON products.id = owners.id JOIN users ON owners.id = user.id GROUP BY product.id Do you have some hints? Thanks

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  • What will or won't cause a thread to block (a question from a test)

    - by fingerprint211b
    I've had a test, and there was a question I lost some points on, because I wasn't able to answer it : Which of the following is NOT a condition which can cause a thread to block : Calling an objects's wait() method Waiting for an I/O operation Calling sleep() Calling yield() Calling join() As far as I know, all of these are blocking calls : wait() returns when an something calls notify(), blocks until then If the thread is WAITING for an I/O operation then it's obviously blocked sleep(), obviously, blocks until the time runs out, or something wakes up the thread yield() "cancels the rest of the thread's timeslice" (lacking a better term), and returns only when the thread is active again join() blocks until the thread it's waiting for terminates. Am I missing something here?

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  • Codeigniter: how do I select count when `$query->num_rows()` doesn't work for me?

    - by mOrloff
    I have a query which is returning a sum, so naturally it returns one row. I need to count the number of records in the DB which made that sum. Here's a sample of the type of query I am talking about (MySQL): SELECT i.id, i.vendor_quote_id, i.product_id_requested, SUM(i.quantity_on_hand) AS qty, COUNT(i.quantity_on_hand) AS count FROM vendor_quote_item AS i JOIN vendor_quote_container AS c ON i.vendor_quote_id = c.id LEFT JOIN company_types ON company_types.company_id = c.company_id WHERE company_types.company_type = 'f' AND i.product_id_requested = 12345678 I have found and am now using the select_min(), select_max(), and select_sum() functions, but my COUNT() is still hard-coded in. The main problem is that I am having to specify the table name in a tightly coupled manner with something like $this->$db->select( 'COUNT(myDbPrefix_vendor_quote_item.quantity_on_hand) AS count' ) which kills portability and makes switching environments a PIA. How can/should I get my the count values I am after with CI in an uncoupled way??

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  • No such file or directory python in linux only (coming from windows)

    - by user1804633
    I have the same exact directory structure within a folder in Windows & in Linux (Debian) - where the script is along the static + dataoutput folders How come the following code works fine in Windows, but gives a no such file or directory path error in linux? @app.route('/_getdataoutputfilelisting') def getdataoutputfilelisting(): listoffilesindataouput = getfiles('static/dataoutput') return jsonify(listoffiles = listoffilesindataouput) def getfiles(dirpath): a = [s for s in os.listdir(dirpath) if os.path.isfile(os.path.join(dirpath, s))] a.sort(key=lambda s: os.path.getmtime(os.path.join(dirpath, s))) a.reverse() return a Is there a way to make it universal such that it works in both OSs? Thanks

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  • mysql query for change in values in a logging table

    - by kiasectomondo
    I have a table like this: Index , PersonID , ItemCount , UnixTimeStamp 1 , 1 , 1 , 1296000000 2 , 1 , 2 , 1296000100 3 , 2 , 4 , 1296003230 4 , 2 , 6 , 1296093949 5 , 1 , 0 , 1296093295 Time and index always go up. Its basically a logging table to log the itemcount each time it changes. I get the most recent ItemCount for each Person like this: SELECT * FROM table a INNER JOIN ( SELECT MAX(index) as i FROM table GROUP BY PersonID) b ON a.index = b.i; What I want to do is get get the most recent record for each PersonID that is at least 24 hours older than the most recent record for each Person ID. Then I want to take the difference in ItemCount between these two to get a change in itemcount for each person over the last 24 hours: personID ChangeInItemCountOverAtLeast24Hours 1 3 2 -11 3 6 Im sort of stuck with what to do next. How can I join another itemcount based on latest adjusted timestamp of individual rows?

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  • Understanding LINQ to SQL (11) Performance

    - by Dixin
    [LINQ via C# series] LINQ to SQL has a lot of great features like strong typing query compilation deferred execution declarative paradigm etc., which are very productive. Of course, these cannot be free, and one price is the performance. O/R mapping overhead Because LINQ to SQL is based on O/R mapping, one obvious overhead is, data changing usually requires data retrieving:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { Product product = database.Products.Single(item => item.ProductID == id); // SELECT... product.UnitPrice = unitPrice; // UPDATE... database.SubmitChanges(); } } Before updating an entity, that entity has to be retrieved by an extra SELECT query. This is slower than direct data update via ADO.NET:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (SqlConnection connection = new SqlConnection( "Data Source=localhost;Initial Catalog=Northwind;Integrated Security=True")) using (SqlCommand command = new SqlCommand( @"UPDATE [dbo].[Products] SET [UnitPrice] = @UnitPrice WHERE [ProductID] = @ProductID", connection)) { command.Parameters.Add("@ProductID", SqlDbType.Int).Value = id; command.Parameters.Add("@UnitPrice", SqlDbType.Money).Value = unitPrice; connection.Open(); command.Transaction = connection.BeginTransaction(); command.ExecuteNonQuery(); // UPDATE... command.Transaction.Commit(); } } The above imperative code specifies the “how to do” details with better performance. For the same reason, some articles from Internet insist that, when updating data via LINQ to SQL, the above declarative code should be replaced by:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.ExecuteCommand( "UPDATE [dbo].[Products] SET [UnitPrice] = {0} WHERE [ProductID] = {1}", id, unitPrice); } } Or just create a stored procedure:CREATE PROCEDURE [dbo].[UpdateProductUnitPrice] ( @ProductID INT, @UnitPrice MONEY ) AS BEGIN BEGIN TRANSACTION UPDATE [dbo].[Products] SET [UnitPrice] = @UnitPrice WHERE [ProductID] = @ProductID COMMIT TRANSACTION END and map it as a method of NorthwindDataContext (explained in this post):private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.UpdateProductUnitPrice(id, unitPrice); } } As a normal trade off for O/R mapping, a decision has to be made between performance overhead and programming productivity according to the case. In a developer’s perspective, if O/R mapping is chosen, I consistently choose the declarative LINQ code, unless this kind of overhead is unacceptable. Data retrieving overhead After talking about the O/R mapping specific issue. Now look into the LINQ to SQL specific issues, for example, performance in the data retrieving process. The previous post has explained that the SQL translating and executing is complex. Actually, the LINQ to SQL pipeline is similar to the compiler pipeline. It consists of about 15 steps to translate an C# expression tree to SQL statement, which can be categorized as: Convert: Invoke SqlProvider.BuildQuery() to convert the tree of Expression nodes into a tree of SqlNode nodes; Bind: Used visitor pattern to figure out the meanings of names according to the mapping info, like a property for a column, etc.; Flatten: Figure out the hierarchy of the query; Rewrite: for SQL Server 2000, if needed Reduce: Remove the unnecessary information from the tree. Parameterize Format: Generate the SQL statement string; Parameterize: Figure out the parameters, for example, a reference to a local variable should be a parameter in SQL; Materialize: Executes the reader and convert the result back into typed objects. So for each data retrieving, even for data retrieving which looks simple: private static Product[] RetrieveProducts(int productId) { using (NorthwindDataContext database = new NorthwindDataContext()) { return database.Products.Where(product => product.ProductID == productId) .ToArray(); } } LINQ to SQL goes through above steps to translate and execute the query. Fortunately, there is a built-in way to cache the translated query. Compiled query When such a LINQ to SQL query is executed repeatedly, The CompiledQuery can be used to translate query for one time, and execute for multiple times:internal static class CompiledQueries { private static readonly Func<NorthwindDataContext, int, Product[]> _retrieveProducts = CompiledQuery.Compile((NorthwindDataContext database, int productId) => database.Products.Where(product => product.ProductID == productId).ToArray()); internal static Product[] RetrieveProducts( this NorthwindDataContext database, int productId) { return _retrieveProducts(database, productId); } } The new version of RetrieveProducts() gets better performance, because only when _retrieveProducts is first time invoked, it internally invokes SqlProvider.Compile() to translate the query expression. And it also uses lock to make sure translating once in multi-threading scenarios. Static SQL / stored procedures without translating Another way to avoid the translating overhead is to use static SQL or stored procedures, just as the above examples. Because this is a functional programming series, this article not dive into. For the details, Scott Guthrie already has some excellent articles: LINQ to SQL (Part 6: Retrieving Data Using Stored Procedures) LINQ to SQL (Part 7: Updating our Database using Stored Procedures) LINQ to SQL (Part 8: Executing Custom SQL Expressions) Data changing overhead By looking into the data updating process, it also needs a lot of work: Begins transaction Processes the changes (ChangeProcessor) Walks through the objects to identify the changes Determines the order of the changes Executes the changings LINQ queries may be needed to execute the changings, like the first example in this article, an object needs to be retrieved before changed, then the above whole process of data retrieving will be went through If there is user customization, it will be executed, for example, a table’s INSERT / UPDATE / DELETE can be customized in the O/R designer It is important to keep these overhead in mind. Bulk deleting / updating Another thing to be aware is the bulk deleting:private static void DeleteProducts(int categoryId) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.Products.DeleteAllOnSubmit( database.Products.Where(product => product.CategoryID == categoryId)); database.SubmitChanges(); } } The expected SQL should be like:BEGIN TRANSACTION exec sp_executesql N'DELETE FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0',N'@p0 int',@p0=9 COMMIT TRANSACTION Hoverer, as fore mentioned, the actual SQL is to retrieving the entities, and then delete them one by one:-- Retrieves the entities to be deleted: exec sp_executesql N'SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued] FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0',N'@p0 int',@p0=9 -- Deletes the retrieved entities one by one: BEGIN TRANSACTION exec sp_executesql N'DELETE FROM [dbo].[Products] WHERE ([ProductID] = @p0) AND ([ProductName] = @p1) AND ([SupplierID] IS NULL) AND ([CategoryID] = @p2) AND ([QuantityPerUnit] IS NULL) AND ([UnitPrice] = @p3) AND ([UnitsInStock] = @p4) AND ([UnitsOnOrder] = @p5) AND ([ReorderLevel] = @p6) AND (NOT ([Discontinued] = 1))',N'@p0 int,@p1 nvarchar(4000),@p2 int,@p3 money,@p4 smallint,@p5 smallint,@p6 smallint',@p0=78,@p1=N'Optimus Prime',@p2=9,@p3=$0.0000,@p4=0,@p5=0,@p6=0 exec sp_executesql N'DELETE FROM [dbo].[Products] WHERE ([ProductID] = @p0) AND ([ProductName] = @p1) AND ([SupplierID] IS NULL) AND ([CategoryID] = @p2) AND ([QuantityPerUnit] IS NULL) AND ([UnitPrice] = @p3) AND ([UnitsInStock] = @p4) AND ([UnitsOnOrder] = @p5) AND ([ReorderLevel] = @p6) AND (NOT ([Discontinued] = 1))',N'@p0 int,@p1 nvarchar(4000),@p2 int,@p3 money,@p4 smallint,@p5 smallint,@p6 smallint',@p0=79,@p1=N'Bumble Bee',@p2=9,@p3=$0.0000,@p4=0,@p5=0,@p6=0 -- ... COMMIT TRANSACTION And the same to the bulk updating. This is really not effective and need to be aware. Here is already some solutions from the Internet, like this one. The idea is wrap the above SELECT statement into a INNER JOIN:exec sp_executesql N'DELETE [dbo].[Products] FROM [dbo].[Products] AS [j0] INNER JOIN ( SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued] FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0) AS [j1] ON ([j0].[ProductID] = [j1].[[Products])', -- The Primary Key N'@p0 int',@p0=9 Query plan overhead The last thing is about the SQL Server query plan. Before .NET 4.0, LINQ to SQL has an issue (not sure if it is a bug). LINQ to SQL internally uses ADO.NET, but it does not set the SqlParameter.Size for a variable-length argument, like argument of NVARCHAR type, etc. So for two queries with the same SQL but different argument length:using (NorthwindDataContext database = new NorthwindDataContext()) { database.Products.Where(product => product.ProductName == "A") .Select(product => product.ProductID).ToArray(); // The same SQL and argument type, different argument length. database.Products.Where(product => product.ProductName == "AA") .Select(product => product.ProductID).ToArray(); } Pay attention to the argument length in the translated SQL:exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(1)',@p0=N'A' exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(2)',@p0=N'AA' Here is the overhead: The first query’s query plan cache is not reused by the second one:SELECT sys.syscacheobjects.cacheobjtype, sys.dm_exec_cached_plans.usecounts, sys.syscacheobjects.[sql] FROM sys.syscacheobjects INNER JOIN sys.dm_exec_cached_plans ON sys.syscacheobjects.bucketid = sys.dm_exec_cached_plans.bucketid; They actually use different query plans. Again, pay attention to the argument length in the [sql] column (@p0 nvarchar(2) / @p0 nvarchar(1)). Fortunately, in .NET 4.0 this is fixed:internal static class SqlTypeSystem { private abstract class ProviderBase : TypeSystemProvider { protected int? GetLargestDeclarableSize(SqlType declaredType) { SqlDbType sqlDbType = declaredType.SqlDbType; if (sqlDbType <= SqlDbType.Image) { switch (sqlDbType) { case SqlDbType.Binary: case SqlDbType.Image: return 8000; } return null; } if (sqlDbType == SqlDbType.NVarChar) { return 4000; // Max length for NVARCHAR. } if (sqlDbType != SqlDbType.VarChar) { return null; } return 8000; } } } In this above example, the translated SQL becomes:exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(4000)',@p0=N'A' exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(4000)',@p0=N'AA' So that they reuses the same query plan cache: Now the [usecounts] column is 2.

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  • Monitoring SQL Server Agent job run times

    - by okeofs
    Introduction A few months back, I was asked how long a particular nightly process took to run. It was a super question and the one thing that struck me was that there were a plethora of factors affecting the processing time. This said, I developed a query to ascertain process run times, the average nightly run times and applied some KPI’s to the end query. The end goal being to enable me to quickly detect anomalies and processes that are running beyond their normal times. As many of you are aware, most of the necessary data for this type of query, lies within the MSDB database. The core portion of the query is shown below.select sj.name,sh.run_date, sh.run_duration, case when len(sh.run_duration) = 6 then convert(varchar(8),sh.run_duration) when len(sh.run_duration) = 5 then '0' + convert(varchar(8),sh.run_duration) when len(sh.run_duration) = 4 then '00' + convert(varchar(8),sh.run_duration) when len(sh.run_duration) = 3 then '000' + convert(varchar(8),sh.run_duration) when len(sh.run_duration) = 2 then '0000' + convert(varchar(8),sh.run_duration) when len(sh.run_duration) = 1 then '00000' + convert(varchar(8),sh.run_duration) end as tt from dbo.sysjobs sj with (nolock) inner join dbo.sysjobHistory sh with (nolock) on sj.job_id = sh.job_id where sj.name = 'My Agent Job' and [sh.Message] like '%The job%') Run_date and run_duration are obvious fields. The field ‘Name’ is the name of the job that we wish to follow. The only major challenge was that the format of the run duration which was not as ‘user friendly’ as I would have liked. As an example, the run duration 1 hour 10 minutes and 3 seconds would be displayed as 11003; whereas I wanted it to display this in a more user friendly manner as 01:10:03. In order to achieve this effect, we need to add leading zeros to the run_duration based upon the case logic shown above. At this point what we need to do add colons between the hours and minutes and one between the minutes and seconds. To achieve this I nested the query shown above (in purple) within a ‘super’ query. Thus the run time ([Run Time]) is constructed concatenating a series of substrings (See below in Blue). select run_date,substring(convert(varchar(20),tt),1,2) + ':' +substring(convert(varchar(20),tt),3,2) + ':' +substring(convert(varchar(20),tt),5,2) as [run_time] from (select sj.name,sh.run_date, sh.run_duration,case when len(sh.run_duration) = 6 then convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 5 then '0' + convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 4 then '00' + convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 3 then '000' + convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 2 then '0000' + convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 1 then '00000' + convert(varchar(8),sh.run_duration)end as ttfrom dbo.sysjobs sj with (nolock)inner join dbo.sysjobHistory sh with (nolock) on sj.job_id = sh.job_id where sj.name = 'My Agent Job'and [sh.Message] like '%The job%') a Now that I had each nightly run time in hours, minutes and seconds (01:10:03), I decided that it would very productive to calculate a rolling run time average. To do this, I decided to do the calculations in base units of seconds. This said, I encapsulated the query shown above into a further ‘super’ query (see the code in RED below). This encapsulation is shown below. The astute reader will note that I used implied casting from integer to string, which is not the best method to use however it works. This said and if I were constructing the query again I would definitely do an explicit convert. To Recap: I now have a key field of ‘1’, each and every applicable run date and the total number of SECONDS that the process ran for each run date, all of this data within the #rawdata1 temporary table. Select 1 as keyy,run_date,(substring(b.run_time,1,2)*3600) + (substring(b.run_time,4,2)*60) + (substring(b.run_time,7,2)) as run_time_in_Seconds,run_time into #rawdata1 from ( select run_date,substring(convert(varchar(20),tt),1,2) + ':' + substring(convert(varchar(20),tt),3,2) + ':' +substring(convert(varchar(20),tt),5,2) as [run_time] from (select sj.name,sh.run_date, sh.run_duration, case when len(sh.run_duration) = 6 then convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 5 then '0' + convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 4 then '00' + convert(varchar(8),sh.run_duration)when len(sh.run_duration)    = 3 then '000' + convert(varchar(8),sh.run_duration)when len(sh.run_duration)    = 2 then '0000' + convert(varchar(8),sh.run_duration)when len(sh.run_duration) = 1 then '00000' + convert(varchar(8),sh.run_duration)end as ttfrom dbo.sysjobs sj with (nolock)inner join dbo.sysjobHistory sh with (nolock)on sj.job_id = sh.job_id where sj.name = 'My Agent Job'and [sh.Message] like '%The job%') a )b   Calculating the average run time We now select each run time in seconds from #rawdata1 and place the values into another temporary table called #rawdata2. Once again we create a ‘key’, a hardwired ‘1’. select 1 as Keyy, run_time_in_Seconds into #rawdata2 from #rawdata1The purpose of doing so is to make the average time AVG() available to the query immediately without having to do adverse grouping. Applying KPI Logic At this point, we shall apply some logic to determine whether processing times are within the norms. We do this by applying colour names. Obviously, this example is a super one for SSRS and traffic light icons.select rd1.run_date, rd1.run_time, rd1.run_time_in_Seconds ,Avg(rd2.run_time_in_Seconds) as Average_run_time_in_seconds,casewhenConvert(decimal(10,1),rd1.run_time_in_Seconds)/Avg(rd2.run_time_in_Seconds)<= 1.2 then 'Green' when Convert(decimal(10,1),rd1.run_time_in_Seconds)/Avg(rd2.run_time_in_Seconds)< 1.4 then 'Yellow' else 'Red'end as [color], Calculating the Average Run Time in Hours Minutes and Seconds and the end of the query. casewhen len(convert(varchar(2),Avg(rd2.run_time_in_Seconds)/(3600))) = 1 then '0' + convert(varchar(2),Avg(rd2.run_time_in_Seconds)/(3600))else convert(varchar(2),Avg(rd2.run_time_in_Seconds)/(3600))end + ':' + case when len(convert(varchar(2),Avg(rd2.run_time_in_Seconds)%(3600)/60)) = 1 then '0' + convert(varchar(2),Avg(rd2.run_time_in_Seconds)%(3600)/60)else convert(varchar(2),Avg(rd2.run_time_in_Seconds)%(3600)/60)end + ':' + case when len(convert(varchar(2),Avg(rd2.run_time_in_Seconds)%60)) = 1 then '0' + convert(varchar(2),Avg(rd2.run_time_in_Seconds)%60)else convert(varchar(2),Avg(rd2.run_time_in_Seconds)%60)end as [Average Run Time HH:MM:SS] from #rawdata2 rd2 innerjoin #rawdata1 rd1on rd1.keyy = rd2.keyygroup by run_date,rd1.run_time ,rd1.run_time_in_Seconds order by run_date descThe complete code example use msdbgo/*drop table #rawdata1drop table #rawdata2go*/select 1 as keyy,run_date,(substring(b.run_time,1,2)*3600) + (substring(b.run_time,4,2)*60) + (substring(b.run_time,7,2)) as run_time_in_Seconds,run_time into #rawdata1 from (select run_date,substring(convert(varchar(20),tt),1,2) + ':' +substring(convert(varchar(20),tt),3,2) + ':' +substring(convert(varchar(20),tt),5,2) as [run_time] from (select name,run_date, run_duration, casewhenlen(run_duration) = 6 then convert(varchar(8),run_duration)whenlen(run_duration) = 5 then '0' + convert(varchar(8),run_duration)whenlen(run_duration) = 4 then '00' + convert(varchar(8),run_duration)whenlen(run_duration) = 3 then '000' + convert(varchar(8),run_duration)whenlen(run_duration) = 2 then '0000' + convert(varchar(8),run_duration)whenlen(run_duration) = 1 then '00000' + convert(varchar(8),run_duration)end as ttfrom dbo.sysjobs sj with (nolock)innerjoin dbo.sysjobHistory sh with (nolock) on sj.job_id = sh.job_id where name = 'My Agent Job'and [Message] like '%The job%') a ) bselect 1 as Keyy, run_time_in_Seconds into #rawdata2 from #rawdata1select rd1.run_date, rd1.run_time, rd1.run_time_in_Seconds ,Avg(rd2.run_time_in_Seconds) as Average_run_time_in_seconds,casewhenConvert(decimal(10,1),rd1.run_time_in_Seconds)/Avg(rd2.run_time_in_Seconds)<= 1.2 then 'Green' when Convert(decimal(10,1),rd1.run_time_in_Seconds)/Avg(rd2.run_time_in_Seconds)< 1.4 then 'Yellow' else 'Red'end as [color],Case when len(convert(varchar(2),Avg(rd2.run_time_in_Seconds)/(3600))) = 1 then '0' + convert(varchar(2),Avg(rd2.run_time_in_Seconds)/(3600))else convert(varchar(2),Avg(rd2.run_time_in_Seconds)/(3600))end + ':' + case when len(convert(varchar(2),Avg(rd2.run_time_in_Seconds)%(3600)/60)) = 1 then '0' + convert(varchar(2),Avg(rd2.run_time_in_Seconds)%(3600)/60)else convert(varchar(2),Avg(rd2.run_time_in_Seconds)%(3600)/60)end + ':' + case when len(convert(varchar(2),Avg(rd2.run_time_in_Seconds)%60)) = 1 then '0' + convert(varchar(2),Avg(rd2.run_time_in_Seconds)%60)else convert(varchar(2),Avg(rd2.run_time_in_Seconds)%60)end as [Average Run Time HH:MM:SS] from #rawdata2 rd2 innerjoin #rawdata1 rd1on rd1.keyy = rd2.keyygroup by run_date,rd1.run_time ,rd1.run_time_in_Seconds order by run_date desc  

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  • WPF TabControl - how to preserve control state within tab items (MVVM pattern)

    - by Tim Coulter
    I am a newcomer to WPF, attempting to build a project that follows the recommendations of Josh Smith's excellent article describing The Model-View-ViewModel Design Pattern. Using Josh's sample code as a base, I have created a simple application that contains a number of "workspaces", each represented by a tab in a TabControl. In my application, a workspace is a document editor that allows a hierarchical document to be manipulated via a TreeView control. Although I have succeeded in opening multiple workspaces and viewing their document content in the bound TreeView control, I find that the TreeView "forgets" its state when switching between tabs. For example, if the TreeView in Tab1 is partially expanded, it will be shown as fully collapsed after switching to Tab2 and returning to Tab1. This behaviour appears to apply to all aspects of control state for all controls. After some experimentation, I have realized that I can preserve state within a TabItem by explicitly binding each control state property to a dedicated property on the underlying ViewModel. However, this seems like a lot of additional work, when I simply want all my controls to remember their state when switching between workspaces. I assume I am missing something simple, but I am not sure where to look for the answer. Any guidance would be much appreciated. Thanks, Tim Update: As requested, I will attempt to post some code that demonstrates this problem. However, since the data that underlies the TreeView is complex, I will post a simplified example that exhibits the same symtoms. Here is the XAML from the main window: <TabControl IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Path=Docs}"> <TabControl.ItemTemplate> <DataTemplate> <ContentPresenter Content="{Binding Path=Name}" /> </DataTemplate> </TabControl.ItemTemplate> <TabControl.ContentTemplate> <DataTemplate> <view:DocumentView /> </DataTemplate> </TabControl.ContentTemplate> </TabControl> The above XAML correctly binds to an ObservableCollection of DocumentViewModel, whereby each member is presented via a DocumentView. For the simplicity of this example, I have removed the TreeView (mentioned above) from the DocumentView and replaced it with a TabControl containing 3 fixed tabs: <TabControl> <TabItem Header="A" /> <TabItem Header="B" /> <TabItem Header="C" /> </TabControl> In this scenario, there is no binding between the DocumentView and the DocumentViewModel. When the code is run, the inner TabControl is unable to remember its selection when the outer TabControl is switched. However, if I explicitly bind the inner TabControl's SelectedIndex property ... <TabControl SelectedIndex="{Binding Path=SelectedDocumentIndex}"> <TabItem Header="A" /> <TabItem Header="B" /> <TabItem Header="C" /> </TabControl> ... to a corresponding dummy property on the DocumentViewModel ... public int SelecteDocumentIndex { get; set; } ... the inner tab is able to remember its selection. I understand that I can effectively solve my problem by applying this technique to every visual property of every control, but I am hoping there is a more elegant solution.

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  • SQL Select syntax error

    - by Odette
    hi guys thanks for your help yesterday. I am now trying to incorporate the query from yesterday into an existing query so I can show the highest itemcode's reporting group in the existing query..but I have a syntax error somewhere at my Select statement. ERROR: Keyword SELECT not expected. I have tried putting brackets at every possible place but still no go..can you please help? (ps-this whole query has been giving me nightmares!) WITH CALC1 AS (SELECT OTQUOT, OTIT01 AS ITEMS, ROUND(OQCQ01 * OVRC01,2) AS COST FROM @[email protected] WHERE OTIT01 < '' UNION ALL SELECT OTQUOT, OTIT02 AS ITEMS, ROUND(OQCQ02 * OVRC02,2) AS COST FROM @[email protected] WHERE OTIT02 < '' UNION ALL SELECT OTQUOT, OTIT03 AS ITEMS, ROUND(OQCQ03 * OVRC03,2) AS COST FROM @[email protected] WHERE OTIT03 < '' UNION ALL SELECT OTQUOT, OTIT04 AS ITEMS, ROUND(OQCQ04 * OVRC04,2) AS COST FROM @[email protected] WHERE OTIT04 < '' UNION ALL SELECT OTQUOT, OTIT05 AS ITEMS, ROUND(OQCQ05 * OVRC05,2) AS COST FROM @[email protected] WHERE OTIT05 < '' UNION ALL SELECT OTQUOT, OTIT06 AS ITEMS, ROUND(OQCQ06 * OVRC06,2) AS COST FROM @[email protected] WHERE OTIT06 < '' UNION ALL SELECT OTQUOT, OTIT07 AS ITEMS, ROUND(OQCQ07 * OVRC07,2) AS COST FROM @[email protected] WHERE OTIT07 < '' UNION ALL SELECT OTQUOT, OTIT08 AS ITEMS, ROUND(OQCQ08 * OVRC08,2) AS COST FROM @[email protected] WHERE OTIT08 < '' UNION ALL SELECT OTQUOT, OTIT09 AS ITEMS, ROUND(OQCQ09 * OVRC09,2) AS COST FROM @[email protected] WHERE OTIT09 < '' UNION ALL SELECT OTQUOT, OTIT10 AS ITEMS, ROUND(OQCQ10 * OVRC10,2) AS COST FROM @[email protected] WHERE OTIT10 < '' ) (SELECT OTQUOT, DESC FROM ( SELECT OTQUOT, ITEMS, B.IXRPGP AS GROUP, C.OTRDSC AS DESC, COST, ROW_NUMBER() OVER (ORDER BY COST DESC) AS RN FROM CALC1 AS A INNER JOIN @[email protected] AS B ON (A.ITEMS = B.IKITMC) INNER JOIN DATAGRP.GDSGRP AS C ON (B.IXRPGP = C.OKRPGP) ) T WHERE T.RN = 1) SELECT A.OKPBRN, A.OCAREA, A.OTCCDE, A.OTCNAM, A.OTSMAN, A.OKPBRN||A.OAPNUM AS OTQUOT, A.OTONUM, A.OTCAD1, A.OTCAD2, A.OTCAD3, A.OTPCDE, A.OTDEL1, A.OTDEL2, A.OTDEL3, CHAR(DATE(CASE WHEN SUBSTR(A.ODOQDT,5,4) = '0000' THEN '0001' ELSE SUBSTR(A.ODOQDT,5,4) END ||'-'|| CASE WHEN SUBSTR(A.ODOQDT,4,2) = '00' THEN '01' ELSE SUBSTR(A.ODOQDT,3,2) END ||'-'|| CASE WHEN SUBSTR(A.ODOQDT,1,2) = '00' THEN '01' ELSE SUBSTR(A.ODOQDT,1,2) END), ISO) AS ODOQDT_CCYYMMDD, CHAR(DATE(CASE WHEN SUBSTR(A.ODDELD,7,2) = '' THEN '0001' ELSE '20'||SUBSTR(A.ODDELD,7,2) END ||'-'|| CASE WHEN SUBSTR(A.ODDELD,4,2) = '' THEN '01' ELSE SUBSTR(A.ODDELD,4,2) END ||'-'|| CASE WHEN SUBSTR(A.ODDELD,1,2) = '' THEN '01' ELSE SUBSTR(A.ODDELD,1,2) END), ISO) AS ODDELD_CCYYMMDD, B.DESC, A.OVQTVL FROM @[email protected] AS A INNER JOIN CALC1 AS B ON (A.OKPBRN||A.OAPNUM = B.OTQUOT) WHERE A.OKPBRN = '@OKPBRN@' AND A.OTCCDE NOT LIKE '*DEP%' AND CHAR(DATE(CASE WHEN SUBSTR(A.ODOQDT,5,4) = '0000' THEN '0001' ELSE SUBSTR (A.ODOQDT,5,4) END ||'-'|| CASE WHEN SUBSTR(A.ODOQDT,4,2) = '00' THEN '01' ELSE SUBSTR(A.ODOQDT,3,2) END ||'-'|| CASE WHEN SUBSTR(A.ODOQDT,1,2) = '00' THEN '01' ELSE SUBSTR(A.ODOQDT,1,2) END), ISO) = CHAR(CURDATE() - 3 MONTH, ISO) AND A.OCQF01 = '0' AND A.OCQF02 = '0' AND A.OCQF04 = '0' AND A.OCQF05 = '0' AND A.OCQF06 = '0' AND A.OCQF07 = '0' AND A.OCQF08 = '0' AND A.OCQF09 = '0' AND A.OCQF10 = '1' AND A.OTCGRP LIKE 'S/%' ORDER BY A.OTSMAN ASC, A.OVQTVL DESC, CHAR(DATE(CASE WHEN SUBSTR(A.ODDELD,7,2) = '' THEN '0001' ELSE '20'||SUBSTR(A.ODDELD,7,2) END ||'-'|| CASE WHEN SUBSTR(A.ODDELD,4,2) = '' THEN '01' ELSE SUBSTR(A.ODDELD,4,2) END ||'-'|| CASE WHEN SUBSTR(A.ODDELD,1,2) = '' THEN '01' ELSE SUBSTR(A.ODDELD,1,2) END),ISO) ASC

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  • Why C# doesn't implement indexed properties ?

    - by Thomas Levesque
    I know, I know... Eric Lippert's answer to this kind of question is usually something like "because it wasn't worth the cost of designing, implementing, testing and documenting it". But still, I'd like a better explanation... I was reading this blog post about new C# 4 features, and in the section about COM Interop, the following part caught my attention : By the way, this code uses one more new feature: indexed properties (take a closer look at those square brackets after Range.) But this feature is available only for COM interop; you cannot create your own indexed properties in C# 4.0. OK, but why ? I already knew and regretted that it wasn't possible to create indexed properties in C#, but this sentence made me think again about it. I can see several good reasons to implement it : the CLR supports it (for instance, PropertyInfo.GetValue has an index parameter), so it's a pity we can't take advantage of it in C# it is supported for COM interop, as shown in the article (using dynamic dispatch) it is implemented in VB.NET it is already possible to create indexers, i.e. to apply an index to the object itself, so it would probably be no big deal to extend the idea to properties, keeping the same syntax and just replacing this with a property name It would allow to write that kind of things : public class Foo { private string[] _values = new string[3]; public string Values[int index] { get { return _values[index]; } set { _values[index] = value; } } } Currently the only workaround that I know is to create an inner class (ValuesCollection for instance) that implements an indexer, and change the Values property so that it returns an instance of that inner class. This is very easy to do, but annoying... So perhaps the compiler could do it for us ! An option would be to generate an inner class that implements the indexer, and expose it through a public generic interface : // interface defined in the namespace System public interface IIndexer<TIndex, TValue> { TValue this[TIndex index] { get; set; } } public class Foo { private string[] _values = new string[3]; private class <>c__DisplayClass1 : IIndexer<int, string> { private Foo _foo; public <>c__DisplayClass1(Foo foo) { _foo = foo; } public string this[int index] { get { return _foo._values[index]; } set { _foo._values[index] = value; } } } private IIndexer<int, string> <>f__valuesIndexer; public IIndexer<int, string> Values { get { if (<>f__valuesIndexer == null) <>f__valuesIndexer = new <>c__DisplayClass1(this); return <>f__valuesIndexer; } } } But of course, in that case the property would actually return a IIndexer<int, string>, and wouldn't really be an indexed property... It would be better to generate a real CLR indexed property. What do you think ? Would you like to see this feature in C# ? If not, why ?

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