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  • COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better?

    - by zneak
    Hello guys, I often find these three variants: SELECT COUNT(*) FROM Foo; SELECT COUNT(1) FROM Foo; SELECT COUNT(PrimaryKey) FROM Foo; As far as I can see, they all do the same thing, and I find myself using the three in my codebase. However, I don't like to do the same thing different ways. To which one should I stick? Is any one of them better than the two others?

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  • How do I convert int? into int

    - by Richard77
    Hello, I've create a SPROC that saves an object and returns the id of the new object saved. Now, I'd like to return an int not an int? public int Save(Contact contact) { int? id; context.Save_And_SendBackID(contact.FirstName, contact.LastName, ref id); //How do I return an int instead of an int? } Thanks for helping

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  • LINQ2SQL: how to merge two columns from the same table into a single list

    - by TomL
    this is probably a simple question, but I'm only a beginner so... Suppose I have a table containing home-work locations (cities) certain people use. Something like: ID(int), namePerson(string), homeLocation(string), workLocation(string) where homeLocation and workLocation can both be null. Now I want all the different locations that are used merged into a single list. Something like: var homeLocation = from hm in Places where hm.Home != null select hm.Home; var workLocation = from wk in Places where wk.Work != null select wk.Work; List<string> locationList = new List<string>(); locationList = homeLocation.Distinct().ToList<string>(); locationList.AddRange(workLocation.Distinct().ToList<string>()); (which I guess would still allow duplicates if they have the same value in both columns, which I don't really want...) My question: how this be put into a single LINQ statement? Thanks in advance for your help!

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  • Advanced LINQ Update Statement

    - by user1902490
    I have a data base with Price_old like: Date --- Hour --- Price _____________________________ Jan 1 --- 1 --- $3.0 Jan 1 --- 2 --- $3.1 Jan 1 --- 3 --- $3.3 Jan 1 --- 4 --- $3.15 Jan 2 --- 1 --- $2.95 Jan 2 --- 2 --- $3.2 Jan 2 --- 3 --- $3.05 What I then have is a spreadsheet, with the same structure, that I will be reading into a datatable, I'll call the new datatable Price_New, note that price new may not have all the same date/hours as Price_Old So, I end up with 2 datatables, Price_Old, and Price_New, and what I need to do is update Price_old with the new prices in Price_New, and then commit those new prices to the Database. I am kinda new to LINQ (about 30 mins of experience) and would really appreciate if someone could give me a pointer or two on whether or not this is doing in LINQ and what the best method would be. Thanks

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  • what is the question for the query?

    - by Kevinniceguy
    Sorry...I mean what question will be for this query? SELECT SUM(price) FROM Room r, Hotel h WHERE r.hotelNo = h.hotelNo and hotelName = 'Paris Hilton' and roomNo NOT IN (SELECT roomNo FROM Booking b, Hotel h WHERE (dateFrom <= CURRENT_DATE AND dateTo >= CURRENT_DATE) AND b.hotelNo = h.hotelNo AND hotelName = 'Paris Hilton');

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  • What are the reasons *not* to use a GUID for a primary key?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • Good strategy for copying a "sliding window" of data from a table?

    - by chiborg
    I have a MySQL table from a third-party application that has millions of rows and only one index - the timestamp of each entry. Now I want to do some heavy self-joins and queries on the data using fields other than the timestamp. Doing the query on the original table would bring the database to a crawl, adding indexes to the table is not an option. Additionally, I only need entries that are newer than one week. My current strategy for doing the queries efficiently is to use a separate table (aux_table) that has the necessary indexes. My questions are: Is there another way to do the queries? and if not, How do I update the data in the indexed table efficiently? So far I have found two approaches for updating aux_table: Truncate aux_table and insert the desired data from the original table. Not very efficient because all the indexes must be re-crated. Check for the biggest timestamp in aux_table and insert all entries with a greater or equal timestamp from the original table. Occasionally drop older entries. Only copying entries with greater timestamp leads to dropped entries (because of entries with same timestamp that were inserted into the original table after the last update).

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  • Single Query returning me 4 tables, How to get all of them back into dataset ?

    - by Shantanu Gupta
    How to fill multiple tables in a dataset. I m using a query that returns me four tables. At the frontend I am trying to fill all the four resultant table into dataset. Here is my Query. Query is not complete. But it is just a refrence for my Ques Select * from tblxyz compute sum(col1) suppose this query returns more than one table, I want to fill all the tables into my dataset I am filling result like this con.open(); adp.fill(dset); con.close(); Now when i checks this dataset. It shows me that it has four tables but only first table data is being displayed into it. rest 3 dont even have schema also. What i need to do to get desired output

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  • SCD2 + Merge Statement + MSSQL

    - by Nev_Rahd
    I am trying work out with MERGE statment to Insert / Update Dimension Table of Type SCD2 My source is a Table var to Merge with Dimension table. My Merget statement is throwing an error as: The target table 'DM.DATA_ERROR.ERROR_DIMENSION' of the INSERT statement cannot be on either side of a (primary key, foreign key) relationship when the FROM clause contains a nested INSERT, UPDATE, DELETE, or MERGE statement. Found reference constraint 'FK_ERROR_DIMENSION_to_AUDIT_CreatedBy'. My Merge Statement: DECLARE @DATAERROROBJECT AS [ERROR_DIMENSION] INSERT INTO DM.DATA_ERROR.ERROR_DIMENSION SELECT ERROR_CODE, DATA_STREAM_ID, [ERROR_SEVERITY], DATA_QUALITY_RATING, ERROR_LONG_DESCRIPTION, ERROR_DESCRIPTION, VALIDATION_RULE, ERROR_TYPE, ERROR_CLASS, VALID_FROM, VALID_TO, CURR_FLAG, CREATED_BY_AUDIT_SK, UPDATED_BY_AUDIT_SK FROM (MERGE DM.DATA_ERROR.ERROR_DIMENSION ED USING @DATAERROROBJECT OBJ ON(ED.ERROR_CODE = OBJ.ERROR_CODE AND ED.DATA_STREAM_ID = OBJ.DATA_STREAM_ID) WHEN NOT MATCHED THEN INSERT VALUES( OBJ.ERROR_CODE ,OBJ.DATA_STREAM_ID ,OBJ.[ERROR_SEVERITY] ,OBJ.DATA_QUALITY_RATING ,OBJ.ERROR_LONG_DESCRIPTION ,OBJ.ERROR_DESCRIPTION ,OBJ.VALIDATION_RULE ,OBJ.ERROR_TYPE ,OBJ.ERROR_CLASS ,GETDATE() ,'9999-12-13' ,'Y' ,1 ,1 ) WHEN MATCHED AND ED.CURR_FLAG = 'Y' AND ( ED.[ERROR_SEVERITY] <> OBJ.[ERROR_SEVERITY] OR ED.[DATA_QUALITY_RATING] <> OBJ.[DATA_QUALITY_RATING] OR ED.[ERROR_LONG_DESCRIPTION] <> OBJ.[ERROR_LONG_DESCRIPTION] OR ED.[ERROR_DESCRIPTION] <> OBJ.[ERROR_DESCRIPTION] OR ED.[VALIDATION_RULE] <> OBJ.[VALIDATION_RULE] OR ED.[ERROR_TYPE] <> OBJ.[ERROR_TYPE] OR ED.[ERROR_CLASS] <> OBJ.[ERROR_CLASS] ) THEN UPDATE SET ED.CURR_FLAG = 'N', ED.VALID_TO = GETDATE() OUTPUT $ACTION ACTION_OUT, OBJ.ERROR_CODE ERROR_CODE, OBJ.DATA_STREAM_ID DATA_STREAM_ID, OBJ.[ERROR_SEVERITY] [ERROR_SEVERITY], OBJ.DATA_QUALITY_RATING DATA_QUALITY_RATING, OBJ.ERROR_LONG_DESCRIPTION ERROR_LONG_DESCRIPTION, OBJ.ERROR_DESCRIPTION ERROR_DESCRIPTION, OBJ.VALIDATION_RULE VALIDATION_RULE, OBJ.ERROR_TYPE ERROR_TYPE, OBJ.ERROR_CLASS ERROR_CLASS, GETDATE() VALID_FROM, '9999-12-31' VALID_TO, 'Y' CURR_FLAG, 555 CREATED_BY_AUDIT_SK, 555 UPDATED_BY_AUDIT_SK ) AS MERGE_OUT WHERE MERGE_OUT.ACTION_OUT = 'UPDATE'; What am i doing wrong ?

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  • Linq ChangeConflictException (ASP.NET MVC) - occurs when submitting DataContext changes

    - by Alex
    System.Data.Linq.ChangeConflictException: 2 of X updates failed. at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) at PROJECT.Controllers.HomeController.ClickProc(Int32 id, String code, String n) This is what I get very often. This action is done thousands of times a day, and I get this exception about once every 5 seconds. From what I understand it happens when something changes in the database in the period between creating DataContext and updating it. Am I right? What's the problem here and how can I fix it?

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  • Is SELECT INTO able to affect data from its original table during UPDATE

    - by driveby
    Whilst asking this question asp.net scheduling timed events user murph posted some insightful information: Point about this is that its very, very simple - you have an process for exchange that is performing a clearly defined task and you have a high frequency task that is not doing anything particularly complex, its a straightforward query (select from table where sent = false and send at < value) - probably into temporary table so that you can run a single query update after you've done the sends - that you can optimise the index for. You're not trying to queue up a huge pile of event triggers, just one that fires once a minute and processes things that are due. Is it possible to SELECT data from table X INTO table Y and have the UPDATES that are performed on table Y pushed into table X? I guess the alternative would be that the data gets updated in table Y then an update command can be run on table X based on the data in table Y. What would be the advantage of selecting into another table? Thank you,

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  • Why does this MySQL function return null?

    - by Shore
    Description: the query actually run have 4 results returned,as can be see from below, what I did is just concate the items then return, but unexpectedly,it's null. I think the code is self-explanatory: DELIMITER | DROP FUNCTION IF EXISTS get_idiscussion_ask| CREATE FUNCTION get_idiscussion_ask(iask_id INT UNSIGNED) RETURNS TEXT DETERMINISTIC BEGIN DECLARE done INT DEFAULT 0; DECLARE body varchar(600); DECLARE created DATETIME; DECLARE anonymous TINYINT(1); DECLARE screen_name varchar(64); DECLARE result TEXT; DECLARE cur1 CURSOR FOR SELECT body,created,anonymous,screen_name from idiscussion left join users on idiscussion.uid=users.id where idiscussion.iask_id=iask_id; DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1; SET result = ''; OPEN cur1; REPEAT FETCH cur1 INTO body, created, anonymous, screen_name; SET result = CONCAT(result,'<comment><body><![CDATA[',body,']]></body>','<replier>',if(screen_name is not null and !anonymous,screen_name,''),'</replier>','<created>',created,'</created></comment>'); UNTIL done END REPEAT; CLOSE cur1; RETURN result; END | DELIMITER ; mysql> DELIMITER ; mysql> select get_idiscussion_ask(1); +------------------------+ | get_idiscussion_ask(1) | +------------------------+ | NULL | +------------------------+ 1 row in set (0.01 sec) mysql> SELECT body,created,anonymous,screen_name from idiscussion left join users on idiscussion.uid=users.id where idiscussion.iask_id=1; +------+---------------------+-----------+-------------+ | body | created | anonymous | screen_name | +------+---------------------+-----------+-------------+ | haha | 2009-05-27 04:57:51 | 0 | NULL | | haha | 2009-05-27 04:57:52 | 0 | NULL | | haha | 2009-05-27 04:57:52 | 0 | NULL | | haha | 2009-05-27 04:57:53 | 0 | NULL | +------+---------------------+-----------+-------------+ 4 rows in set (0.00 sec) For those who don't think the code is self-explanatory: Why the function returns NULL?

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  • How to get an id from the results in two tables

    - by Chris Lively
    Consider an order. An order will have one or more line items. Each line item is for a particular product. Given a filter table with a couple of products, how would I get the order id's that had at least all of the products listed in the second table? table Orders( OrderId int ) table LineItems ( OrderId int, LineItemId int, ProductId int ) table Filter ( ProductId int ) data Orders OrderId -------- 1 2 3 LineItems OrderId LineItemId ProductId ------- ---------- --------- 1 1 401 1 2 502 2 3 401 3 4 401 3 5 603 3 6 714 Filter ProductId --------- 401 603 Desired result of the query: OrderId: 3

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  • Copying Some from a PostgreSQL Server to Another

    - by whollychao
    I am in need of an application that can periodically transmit select rows from a PostgreSQL database across a network to a second PostgreSQL server. Typically these will be the most recent row added, pulled and transmitted every 10-30 seconds. The primary servers run in a MS Windows environment with a high-latency, and occasionally intermittent, network connection. Therefore, any application would have to be tolerant of this and ideally automatically reconnect / resend data that could not be transmitted. Due to the environment and the requirements, a full-blown replication package would be unnecessary. I appreciate any help anyone has with this problem.

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  • How to save multiple column in database

    - by shamim
    I have a text file.I need to get data from this text file and show on grid , 1)After this user can update information from gridview, 2)Click on save button save data on database. Before clicking on button data don't save on database.How to do that?

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  • when i download file from my website which contains grid and in one of the column of grid there is d

    - by SmartDev
    Hi, I have page called filedownload.aspx , it contains grid and in grid they are three columns and in one of the column there is button which says Download , when user clicks on that button it picks file id and gives the download box to user with three options Open save and cancel . Now the problem is that when user clicks on the download button in grid it gives this ERROR: INTERNET EXPLORER CANNOT DOWNLOAD FILEDOWNLOAD.ASPX FROM ABC.XYZ.COM (MY URL EXAMPLE) INTERNET EXPLORER WAS NOT ABLE TO OPEN THIS SITE .THE REQUEST SITE IS EITHER UNAVAILABLE OR CANNOT BE FOUND . ONE MORE THING IS THT RECENTLY WE IMPLEMENTED SSL AND FROM HTTP WE MOVE TO HTTPS WITH NAME CHANGE IN URL ALSO BFEORE IT WAS AND NOW ITS . NOW WHEN I CHANGE THE URL TO OLD ONE THE PAGE IS WORKING FINE . CAN ANYONE HELP ME ON THIS ? THANKS, SMARTDEV

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  • Need help with this SQL

    - by Bragaadeesh
    Hi guys, I am very very new to mysql. I am trying to execute the following query. update share set holder = 22 where SHARE_ID IN (select SHARE_ID from SHARE WHERE holder=1 LIMIT 10) When I try to execute the above query I am getting this error #1235 - This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'

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  • Insert multiple records from a XML string differing on one parameter in SQL SERVER 2008

    - by Rohit
    Below in a query which inserts records to SimpleDictationProfileMapping table after reading it from a XML string. Now this query inserts a single record in which DictationCaptureProfileID is @dictationCaptureProfileId . Now i want to insert multiple rows in which @dictationCaptureProfileId is different and other 2 values are same. What i want to achieve by this is in case parent changes all child values should also change. INSERT INTO SimpleDictationProfileMapping ( DictationCaptureProfileID, DictationProfileMappingAttributeID, DictationProfileMappingAttributeValue ) SELECT @dictationCaptureProfileId, row.value('@attrId','varchar(max)'), row.value('@value', 'varchar(max)') FROM @simpleDictationCaptureProfileMappings.nodes('/simpleMappingAtribute/attribute') AS d ( row ) ; I want INSERT INTO SimpleDictationProfileMapping ( DictationCaptureProfileID OR (SELECT DictationCaptureProfileID FROM DictationCaptureProfile WHERE SystemDictationCaptureProfileID = @systemDictationCaptureProfileID), DictationProfileMappingAttributeID, DictationProfileMappingAttributeValue ) SELECT @dictationCaptureProfileId , row.value('@attrId','varchar(max)'), row.value('@value', 'varchar(max)') FROM @simpleDictationCaptureProfileMappings.nodes ('/simpleMappingAtribute/attribute') AS d ( row ) ; Please tell how to achieve this.

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  • Does clustered index on foreign key column increase join performance vs non-clustered ?

    - by alpav
    In many places it's recommended that clustered indexes are better utilized when used to select range of rows using BETWEEN statement. When I select joining by foreign key field in such a way that this clustered index is used, I guess, that clusterization should help too because range of rows is being selected even though they all have same clustered key value and BETWEEN is not used. Considering that I care only about that one select with join and nothing else, am I wrong with my guess ?

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  • Tool Compare the tables in two different databeses

    - by user191124
    I am using Toad. Frequently i need to compare tables in two different test environments. the tables present in them are same but the data differs. i just need to know what are the differences in the same tables which are in two different data bases.Are there any tools which can be installed on windows and use it to compare. Much appreciate your help:)

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  • MySQL db Audit Trail Trigger

    - by Natkeeran
    I need to track changes (audit trail) in certain tables in a MySql Db. I am trying to implement the solution suggested here. I have an AuditLog Table with the following columns: AuditLogID, TableName, RowPK, FieldName, OldValue, NewValue, TimeStamp. The mysql stored procedure is the following (this executes fine, and creates the procedure): The call to the procedure such as: CALL addLogTrigger('ProductTypes', 'ProductTypeID'); executes, but does not create any triggers (see the image). SHOW TRIGGERS returns empty set. Please let me know what could be the issue, or an alternate way to implement this. DROP PROCEDURE IF EXISTS addLogTrigger; DELIMITER $ CREATE PROCEDURE addLogTrigger(IN tableName VARCHAR(255), IN pkField VARCHAR(255)) BEGIN SELECT CONCAT( 'DELIMITER $\n', 'CREATE TRIGGER ', tableName, '_AU AFTER UPDATE ON ', tableName, ' FOR EACH ROW BEGIN ', GROUP_CONCAT( CONCAT( 'IF NOT( OLD.', column_name, ' <=> NEW.', column_name, ') THEN INSERT INTO AuditLog (', 'TableName, ', 'RowPK, ', 'FieldName, ', 'OldValue, ', 'NewValue' ') VALUES ( ''', table_name, ''', NEW.', pkField, ', ''', column_name, ''', OLD.', column_name, ', NEW.', column_name, '); END IF;' ) SEPARATOR ' ' ), ' END;$' ) FROM information_schema.columns WHERE table_schema = database() AND table_name = tableName; END$ DELIMITER ;

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  • RDLC item width is dynamic and causing extra pages to be generated (image included)?

    - by Paul Mendoza
    I'm trying to format an RDLC report file in Visual Studio 2008 and I am having a formatting issue. I have a list at the bottom that contains a matrix that expands horizontally to the right. That pink box is just to visualize the problem I'm having. When the report is rendered the matrix expands and instead of filling the pink box with the matrix is pushes the space in the pink box to the right resulting in an extra page when printing the reports. One solution would be to shrink the pink box to be the size of the matrix which I've done. But then when the matrix grows the fields at the top of the report get pushed to the right by the same amount as the growth of the matrix. Can someone please let me know what they think the solution would be? Thank you!

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  • Querying with foreign key

    - by theactiveactor
    Say I have 2 tables whose structures are as follows: tableA id | A1 | A2 tableB id | tableA_id (foreign key) | B1 Entries in A have a one-to-many relationship with entries in B. What kind of query operation would I need to achieve "something like this: select all objects from table B where A1="foo""? Basically, apply a query on tableA and from those result, find corresponding dependent objects in tableB

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