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  • Cannot add an entity that already exists.

    - by mazhar
    Code: public ActionResult Create(Group group) { if (ModelState.IsValid) { group.int_CreatedBy = 1; group.dtm_CreatedDate = DateTime.Now; var Groups = Request["Groups"]; int GroupId = 0; GroupFeature GroupFeature=new GroupFeature(); foreach (var GroupIdd in Groups) { // GroupId = int.Parse(GroupIdd.ToString()); } var Features = Request["Features"]; int FeatureId = 0; int t = 0; int ids=0; string[] Feature = Features.Split(',').ToArray(); //foreach (var FeatureIdd in Features) for(int i=0; i<Feature.Length; i++) { if (int.TryParse(Feature[i].ToString(), out ids)) { GroupFeature.int_GroupId = 35; GroupFeature.int_FeaturesId = ids; if (ids != 0) { GroupFeatureRepository.Add(GroupFeature); GroupFeatureRepository.Save(); } } } return RedirectToAction("Details", new { id = group.int_GroupId }); } return View(); } I am getting an error here Cannot add an entity that already exists. at this line GroupFeatureRepository.Add(GroupFeature); GroupFeatureRepository.Save();

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  • Can in-memory SQLite databases scale with concurrency?

    - by Kent Boogaart
    In order to prevent a SQLite in-memory database from being cleaned up, one must use the same connection to access the database. However, using the same connection causes SQLite to synchronize access to the database. Thus, if I have many threads performing reads against an in-memory database, it is slower on a multi-core machine than the exact same code running against a file-backed database. Is there any way to get the best of both worlds? That is, an in-memory database that permits multiple, concurrent calls to the database?

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  • Designing a table to store EXIF data

    - by rafale
    I'm looking to get the best performance out of querying a table containing EXIF data. The queries in question will only search the EXIF data for the specified strings and return the row index on a match. With that said, would it better to store the EXIF data in a table with separate columns for each of the tags, or would storing all of the tags in a single column as one long delimited string suit me just as well? There are around 115 EXIF tags I'll be storing, and each record would be around 1500 to 2000 chars in length if concatenated into a single string.

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  • Adding relative week number column to MySQl results

    - by Anthony
    I have a table with 3 columns: user, value, and date. The main query returns the values for a specific user based on a date range: SELECT date, value FROM values WHERE user = '$user' AND date BETWEEN $start AND $end What I would like is for the results to also have a column indicating the week number relative to the date range. So if the date range is 1/1/2010 - 1/20/2010, then any results from the first Sun - Sat of that range are week 1, the next Sun - Sat are week 2, etc. If the date range starts on a Saturday, then only results from that one day would be week 1. If the date range starts on Thursday but the first result is on the following Monday, it would be week 2, and there are no week 1 results. Is this something fairly simple to add to the query? The only ideas I can come up with would be based on the week number for the year or the week number based on the results themselves (where in that second example above, the first result always gets week 1).

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  • Java: JPQL search -similar- strings

    - by bguiz
    What methods are there to get JPQL to match similar strings? By similar I mean: Contains: search string is found within the string of the matches entity Case-insensitive Small mispellings: e.g. "arow" matches "arrow" I suspect the first two will be easy, however, I would appreciate help with the last one Thank you

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  • Why are joins bad when considering scalability?

    - by acidzombie24
    Why are joins bad or 'slow'. I know i heard this more then once. I found this quote The problem is joins are relatively slow, especially over very large data sets, and if they are slow your website is slow. It takes a long time to get all those separate bits of information off disk and put them all together again. source I always thought they were fast especially when looking up a PK. Why are they 'slow'?

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  • How to retrieve last primary Id from mdb's table?

    - by William
    I got table with next columns: Id, Name, Age, Class I am trying to insert new row in db like this: INSERT INTO MyTable (Name, Age, Class) VALUES (@name, @age, @class) And get an exeption: "Index or primary key cannot contain a Null value." The question is how to add a new row without knowing next primary Id, or maybe there is a way to get this Id from the table with the help of another query ?

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  • What are the rules governing how a bind variable can be used in Postgres and where is this defined?

    - by Craig Miles
    I can have a table and function defined as: CREATE TABLE mytable ( mycol integer ); INSERT INTO mytable VALUES (1); CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol = l_myvar; RETURN l_myrow; END; $$ LANGUAGE plpgsql; In this case l_myvar acts as a bind variable for the value passed when I call: SELECT * FROM myfunction(1); and returns the row where mycol = 1 If I redefine the function as: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (l_myvar); RETURN l_myrow; END; $$ LANGUAGE plpgsql; SELECT * FROM myfunction(1); still returns the row where mycol = 1 However, if I now change the function definition to allow me to pass an integer array and try to this array in the IN clause, I get an error: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer[]) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (array_to_string(l_myvar, ',')); RETURN l_myrow; END; $$ LANGUAGE plpgsql; Analysis reveals that although: SELECT array_to_string(ARRAY[1, 2], ','); returns 1,2 as expected SELECT * FROM myfunction(ARRAY[1, 2]); returns the error operator does not exist: integer = text at the line: WHERE mycol IN (array_to_string(l_myvar, ',')); If I execute: SELECT * FROM mytable WHERE mycol IN (1,2); I get the expected result. Given that array_to_string(l_myvar, ',') evaluates to 1,2 as shown, why arent these statements equivalent. From the error message it is something to do with datatypes, but doesnt the IN(variable) construct appear to be behaving differently from the = variable construct? What are the rules here? I know that I could build a statement to EXECUTE, treating everything as a string, to achieve what I want to do, so I am not looking for that as a solution. I do want to understand though what is going on in this example. Is there a modification to this approach to make it work, the particular example being to pass in an array of values to build a dynamic IN clause without resorting to EXECUTE? Thanks in advance Craig

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  • T-SQL Query, combine columns from multiple rows into single column

    - by Shayne
    I have seeen some examples of what I am trying to do using COALESCE and FOR XML (seems like the better solution). I just can't quite get the syntax right. Here is what I have (I will shorten the fields to only the key ones): Table Fields ------ ------------------------------- Requisition ID, Number IssuedPO ID, Number Job ID, Number Job_Activity ID, JobID (fkey) RequisitionItems ID, RequisitionID(fkey), IssuedPOID(fkey), Job_ActivityID (fkey) I need a query that will list ONE Requisition per line with its associated Jobs and IssuedPOs. (The requisition number start with "R-" and the Job Number start with "J-"). Example: R-123 | "PO1; PO2; PO3" | "J-12345; J-6780" Sure thing Adam! Here is a query that returns multiple rows. I have to use outer joins, since not all Requisitions have RequisitionItems that are assigned to Jobs and/or IssuedPOs (in that case their fkey IDs would just be null of course). SELECT DISTINCT Requisition.Number, IssuedPO.Number, Job.Number FROM Requisition INNER JOIN RequisitionItem on RequisitionItem.RequisitionID = Requisition.ID LEFT OUTER JOIN Job_Activity on RequisitionItem.JobActivityID = Job_Activity.ID LEFT OUTER JOIN Job on Job_Activity.JobID = Job.ID LEFT OUTER JOIN IssuedPO on RequisitionItem.IssuedPOID = IssuedPO.ID

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  • MySQL: Efficient Blobbing?

    - by feklee
    I'm dealing with blobs of up to - I estimate - about 100 kilo bytes in size. The data is compressed already. Storage engine: InnoDB on MySQL 5.1 Frontend: PHP (Symfony with Propel ORM) Some questions: I've read somewhere that it's not good to update blobs, because it leads to reallocation, fragmentation, and thus bad performance. Is that true? Any reference on this? Initially the blobs get constructed by appending data chunks. Each chunk is up to 16 kilo bytes in size. Is it more efficient to use a separate chunk table instead, for example with fields as below? parent_id, position, chunk Then, to get the entire blob, one would do something like: SELECT GROUP_CONCAT(chunk ORDER BY position) FROM chunks WHERE parent_id = 187 The result would be used in a PHP script. Is there any difference between the types of blobs, aside from the size needed for meta data, which should be negligible.

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  • Data historian queries

    - by Scott Dennis
    Hi, I have a table that contains data for electric motors the format is: DATE(DateTime) | TagName(VarChar(50) | Val(Float) | 2009-11-03 17:44:13.000 | Motor_1 | 123.45 2009-11-04 17:44:13.000 | Motor_1 | 124.45 2009-11-05 17:44:13.000 | Motor_1 | 125.45 2009-11-03 17:44:13.000 | Motor_2 | 223.45 2009-11-04 17:44:13.000 | Motor_2 | 224.45 Data for each motor is inserted daily, so there would be 31 Motor_1s and 31 Motor_2s etc. We do this so we can trend it on our control system displays. I am using views to extract last months max val and last months min val. Same for this months data. Then I join the two and calculate the difference to get the actual run hours for that month. The "Val" is a nonresetable Accumulation from a PLC(Controller). This is my query for Last months Max Value: SELECT TagName, Val AS Hours FROM dbo.All_Data_From_Last_Mon AS cur WHERE (NOT EXISTS (SELECT TagName, Val FROM dbo.All_Data_From_Last_Mon AS high WHERE (TagName = cur.TagName) AND (Val > cur.Val))) This is my query for Last months Max Value: SELECT TagName, Val AS Hours FROM dbo.All_Data_From_Last_Mon AS cur WHERE (NOT EXISTS (SELECT TagName, Val FROM dbo.All_Data_From_Last_Mon AS high WHERE (TagName = cur.TagName) AND (Val < cur.Val))) This is the query that calculates the difference and runs a bit slow: SELECT dbo.Motors_Last_Mon_Max.TagName, STR(dbo.Motors_Last_Mon_Max.Hours - dbo.Motors_Last_Mon_Min.Hours, 12, 2) AS Hours FROM dbo.Motors_Last_Mon_Min RIGHT OUTER JOIN dbo.Motors_Last_Mon_Max ON dbo.Motors_Last_Mon_Min.TagName = dbo.Motors_Last_Mon_Max.TagName I know there is a better way. Ultimately I just need last months total and this months total. Any help would be appreciated. Thanks in advance

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  • I got an error when implementing tde in sql2008

    - by mahima
    while using USE mssqltips_tde; CREATE DATABASE ENCRYPTION KEY with ALGORITHM = AES_256 ENCRYPTION BY SERVER CERTIFICATE TDECert GO getting error Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'KEY'. Msg 319, Level 15, State 1, Line 3 Incorrect syntax near the keyword 'with'. If this statement is a common table expression or an xmlnamespaces clause, the previous statement must be terminated with a semicolon. please help in resolving the same as i need to implement Encryption on my DB

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  • Right way to implement a n-to-m related

    - by ThreeFingerMark
    Hello, this is a part from my database structure: Table: Item Columns: ItemID, Title, Content, Price Table: Tag Columns: TagID, Title Table: ItemTag Columns: ItemID, TagID Table: Image Columns: ImageID, Path, Size, UploadDate Table: ItemImage Columns: ItemID, ImageID The items can have more than one image so i have a extra table "Image" and map this images to an items. I see now a problem with this structure. Before i can add Images i must enter an item. My question is now. Is this structure a good way to solve my problem with many images / tags for one item? Thank you

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  • mysql replace matching but not changing

    - by alex
    I've used mysql's update replace function before, but even though I think I'm following the same syntax, I can't get this to work-it matches the rows, but doesn't replace. Here's what I'm trying to do: mysql> update contained_widgets set preference_values = replace(preference_values, '<li><a_href="/enewsletter"><span class="not-tc">eNewsletter</span></a></li>', '<li><a_href="/enewsletter"><span class="not-tc">eNewsletter</span></a></li> <li> <a_href="/projects"><span class="not-tc">Projects</span></a></li>'); Query OK, 0 rows affected (0.00 sec) Rows matched: 77 Changed: 0 Warnings: 0 I don't see what I'm missing. Any help is appreciated. I edited "a " to "a_" because the site thinks I'm posting spam links otherwise.

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  • oracle search word in string

    - by Atul
    I want to search a word in string in ORACLE in which string is comma separated. Eg. String is ('MF1,MF2,MF3') and now I want to search whether 'MF' exists in that or not. If I am using instr('MF1,MF2,MF3','MF') it will give wrong result since I want to search Full MF in MF1 or MF2 or MF3.

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  • Conditional SELECT MySQL

    - by user188693
    Don't know if this is possible, but I'd like to select records based on the field value of recur_type, where the 'm' is the day of the week. If it's a weekly recurring event, I need to make sure this is a day it recurs on, otherwise, I want to return all days. however, I'm getting an empty result set: SELECT * FROM wp_fun_bec_events WHERE start_date <= '2009-10-12' AND ( end_date >= '2009-10-12' OR (recur_end > '0' AND recur_end >= '2009-10-12' ) ) AND ('m' IN ( CASE WHEN 'recur_type' = 'weekly' THEN recur_days ELSE 's/m/t/w/r/f/a' END ) ) ORDER BY start_date, start_time Any ideas??

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  • How to apply GROUP_CONCAT in mysql Query

    - by Query Master
    How to apply GROUP_CONCAT in this Query if you guys have any idea or any alternate solution about this please share me. Helps are definitely appreciated also (see Query or result required) Query SELECT WEEK(cpd.added_date) AS week_no,COUNT(cpd.result) AS death_count FROM cron_players_data cpd WHERE cpd.player_id = 81 AND cpd.result = 2 AND cpd.status = 1 GROUP BY WEEK(cpd.added_date); Query output result screen Result Required 23,24,25 AS week_no 2,3,1 AS death_count

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  • Calculate open timeslots given availability and existing appointments - by day

    - by Andre
    Overview: I have a table which stores a persons "availability" for a current day, e.g. Mon - 8:00am - 11:30am Mon - 1:30pm - 6:00pm A second table stores appointments that this person already has for the same day, e.g. Mon - 8:30am - 11:00am Mon - 2:30pm - 4pm Desired result: Doing calculationsI'd like to have the following result - e.g. "this person has availability on the given day": Mon - 8:00am - 8:30am Mon - 11:00am - 11:30am Mon - 1:30pm - 2:30pm Mon - 4:00pm - 6:00pm Any ideas on how to calculate the output given the two inputs (e.g. availability, existing appointments) would be greatly appreciated. Preferably I'd use javascript on the client to do the calculating as I would believe that doing it within the DB (I'm using MSSQL) would be slow for many records, persons, etc. Hope this is enough information to illustrate the problem at hand - Many thanks in advance.

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