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  • how to select the records whose several fields' combination will equal to a specific value

    - by poiu2000
    Hi all, Assume I have the following style table, col1 col2 and col3 have same value scopes, I want to select the records when two of the 3 columns have a value combination such as ('ab' and 'bc'), in the following example, the first 3 records should be selected. Any good way to do this? I am using Sybase. | id | col1 | col2 | col3 | 1 ab bc null 2 null ab bc 3 ab ab bc 4 de ab xy Thanks.

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  • How does linq decide between inner & outer joins

    - by user287795
    Hi Usually linq is using an left outer join for its queries but on some cases it decides to use inner join instead. I have a situation where that decision results in wrong results since the second table doesn't always have suitable records and that removes the records from the first table. I'm using a linqdatasource over a dbml where the relevant tables are identical but one holds historical records removed from the first. both have the same primary key. and I'm using a dataloadoption to load both tables at once with out round trips. Would you explain why linq decided to use an inner join here? Thanks

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  • Problem with Nulls and an UPDATE statement

    - by Dave
    UPDATE TableA SET Value = a.Value * b.AnotherValue FROM TableA AS a INNER JOIN TableB AS b WHERE (Condition is true); Here is the problem. The Value field for TableA does not allow nulls. If the calculation of a.Value * b.AnotherValue yields a null, an error is thrown. Now the question. Is there any way to tell the UPDATE to ignore the SET phase when the result of the calculation is a null and delete the record rather than updating it. This UPDATE is intended to update hundreds of records at a time but will fail if a single null is encountered. Also, please note that using the ISNULL() function and setting the Value to zero is not acceptable. I would like the record to be dropped if a null is encountered. Many thanks in advance for any help rendered.

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  • Update table with index is too slow

    - by pauloya
    Hi, I was watching the Profiler on a live system of our application and I saw that there was an update instruction that we run periodically (every second) that was quite slow. It took around 400ms every time. The query includes this update (which is the slow part) UPDATE BufferTable SET LrbCount = LrbCount + 1, LrbUpdated = getdate() WHERE LrbId = @LrbId This is the table CREATE TABLE BufferTable( LrbId [bigint] IDENTITY(1,1) NOT NULL, ... LrbInserted [datetime] NOT NULL, LrbProcessed [bit] NOT NULL, LrbUpdated [datetime] NOT NULL, LrbCount [tinyint] NOT NULL, ) The table has 2 indexes (non unique and non clustered) with the fields by this order: * Index1 - (LrbProcessed, LrbCount) * Index2 - (LrbInserted, LrbCount, LrbProcessed) When I looked at this I thought that the problem would come from Index1 since LrbCount is changing a lot and it changes the order of the data in the index. But after desactivating index1 I saw the query was taking the same time as initially. Then I rebuilt index1 and desactivated index2, this time the query was very fast. It seems to me that Index2 should be faster to update, the order of the data shouldn't change since the LrbInserted time is not changed. Can someone explain why index2 is much heavier to update then index1? Thank you!

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  • Optimizing MySQL queries with IN operator

    - by Arkadiusz Kondas
    I have a MySQL database with a fairly large table where the products are. Each of them has its own id and categoryId field where there is a category id belongs to this product. Now I have a query that pulls out products from given categories such as: SELECT * FROM products WHERE categoryId IN ( 1, 2, 3, 4, 5, 34, 6, 7, 8, 9, 10, 11, 12 ) Of course, come a WHERE clause and ORDER BY sort but not in this thing. Let's say that these products is 250k and the visits are over 100k per day. Under such conditions in the table slow_log registered weight of these queries with large generation time. Do you have any ideas how to optimize the given problem? Table engine is MyISAM.

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  • trigger execution against condition satisfaction

    - by maheshasoni
    I have created this trigger which should give a error, whenever the value of new rctmemenrolno of table-receipts1 is matched with the memenrolno of table- memmast, but it is giving error in both condition(it is matched or not matched). kindly help me. CREATE OR REPLACE TRIGGER HDD_CABLE.trg_rctenrolno before insert ON HDD_CABLE.RECEIPTS1 for each row declare v_enrolno varchar2(9); cursor c1 is select memenrolno from memmast; begin open c1; fetch c1 into v_enrolno; LOOP If :new.rctmemenrolno<>v_enrolno then raise_application_error(-20186,'PLEASE ENTER CORRECT ENROLLMENT NO'); close c1; end if; END LOOP; end;

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  • Can I Use EF Across Multiple DBs in One SQLServer Instance?

    - by thomashubschman
    Hello, I have been searching the blogs and articles but I have not found much support for this scenario. I have been poking around EF and realized that I could create views that contained data from multiple databases and then build the EF object model off of those views. Although it works I am not sure about the usual issues of performance, scalability, maintainability. The way I am achieving the connection between databases is by creating associations in the EF model. Does anyone have any information about this type of implementation? Either another solution or commentary on this proposed solution? Thanks, Tom

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  • correct mysql syntax error

    - by user2981651
    please could someone tell me the problem with this syntax because mysql 5.5.32 keeps tell me about an error CREATE TABLE `clients` ( `ID` tinyint(11) NOT NULL auto_increment, `title` varchar(10) NOT NULL default '', `firstName` varchar(30) NOT NULL default '', `lastName` varchar(30) NOT NULL default '', `address1` varchar(100) NOT NULL default '', `address2` varchar(100) NOT NULL default '', `town` varchar(100) NOT NULL default '', `province` varchar(100) NOT NULL default '', `country` varchar(40) NOT NULL default '', `postCode` varchar(20) NOT NULL default '', `telephone` varchar(20) NOT NULL default '', `email` varchar(100) NOT NULL default '', `cardNo` varchar(16) NOT NULL default '0000-00-00', `expiryDate` date NOT NULL default '0000-00-00', PRIMARY KEY (`ID`) ) TYPE=MyISAM COMMENT='customer table' AUTO_INCREMENT=1 ;

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  • mysql count(*) left join group by - the number of files in a folder

    - by Flavius
    Hi I have the following tables CREATE TABLE `files` ( `fileid` int(11) NOT NULL AUTO_INCREMENT, `filename` varchar(255) NOT NULL, `filesize` int(11) NOT NULL, `folder` int(11) NOT NULL, PRIMARY KEY (`fileid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE `folders` ( `directoryid` int(11) NOT NULL AUTO_INCREMENT, `directoryname` varchar(255) NOT NULL, PRIMARY KEY (`directoryid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; How to get a list of all folders and the number of files they hold, including folders who have no (zero) files? Recursion must not be taken into account. Found it select folders.directoryid, folders.directoryname, count(files.fileid) as no_files from folders left join files on files.folder = folders.directoryid group by folders.directoryid, folders.directoryname I hope it will help someone.

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  • help with sql query - in access 2007

    - by Gold
    hi i have 2 tables table items has 144602 records table A has 27721 records code in items = BAR8 in A i want to show all records that equal i try this: SELECT Items.Code, A.BAR8 FROM Items INNER JOIN A ON Items.Code = A.BAR8; and i get 28048 records !!! i need to get 27721 , how to do it ? thank's in advance

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  • How do I exclude outliers from an aggregate query?

    - by Margaret
    I'm creating a report comparing total time and volume across units. Here a simplification of the query I'm using at the moment: SELECT m.Unit, COUNT(*) AS Count, SUM(m.TimeInMinutes) AS TotalTime FROM main_table m WHERE m.unit <> '' AND m.TimeInMinutes > 0 GROUP BY m.Unit HAVING COUNT(*) > 15 However, I have been told that I need to exclude cases where the row's time is in the highest or lowest 5% to try and get rid of a few wacky outliers. (As in, remove the rows before the aggregates are applied.) How do I do that?

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  • Showing an image after laoding it from sql database

    - by user330075
    I have a problem showing the image form database in a view Details and a ImageController. Inside the view i have: img src=Url.Action("GetFile","Image", new {id= Model.id}) and in controller: public FileContentResult GetFile(int idl) { //int idl = 32; SqlDataReader rdr; byte[] fileContent = null; ........... return File(,,); } When the view is called, function GetFile it just wont work,but if i cut out the parameter int id1 and i instantiate it as a variable it'l work. public FileContentResult GetFile() { int idl = 32; SqlDataReader rdr; byte[] fileContent = null; ........... return File(,,); } Why?

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  • Counting the instances of customers

    - by Mikae Combarado
    Say that I have a table with one column named CustomerId. The example of the instance of this table is : CustomerId 14 12 11 204 14 204 I want to write a query that counts the number of occurences of customer IDs. At the end, I would like to have a result like this : CustomerId NumberOfOccurences 14 2 12 1 11 1 204 2 14 1 I cannot think of a way to do this.

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  • removing comma from string array

    - by sarah
    Hi, I want to execute a query like select ID from "xyz_DB"."test" where user in ('a','b') so the corresponding code is like String s="("; for(String user:selUsers){ s+= " ' " + user + " ', "; } s+=")"; Select ID from test where userId in s; The following code is forming the value of s as ('a','b',) i want to remove the comma after the end of array how to do this ?

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  • How do database servers decide which order to return rows without any "order by" statements?

    - by Chris
    Kind of a whimsical question, always something I've wondered about and I figure knowing why it does what it does might deepen my understanding a bit. Let's say I do "SELECT TOP 10 * FROM TableName". In short timeframes, the same 10 rows come back, so it doesn't seem random. They weren't the first or last created. In my massive sample size of...one table, it isn't returning the min or max auto-incrementing primary key value. I also figure the problem gets more complex when taking joins into account. My database of choice is MSSQL, but I figure this might be an interesting question regardless of the platform.

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  • distinction between using .text and .value in VBA access

    - by every_answer_gets_a_point
    i am passing the textbox1.text values into a query and sometimes into a string sometimes i say this: dim combor1 as string combor1 = comboReason1.Text how do i know when i should put combor1=comboreason1.value ?? also why do i need to set focus for a control to reference its property? that doesn't make sense to me also when i set combor4 = comboReason4.Value and the .value is null, then i get an error about invalid use of null please help!

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  • PHP Try and Catch for SQL Insert

    - by meme
    I have a page on my website (high traffic) that does an insert on every page load. I am curious of the fastest and safest way to (catch an error) and continue if the system is not able to do the insert into MySQL. Should I use try/catch or die or something else. I want to make sure the insert happens but if for some reason it can't I want the page to continue to load anyway. ... $db = mysql_select_db('mobile', $conn); mysql_query("INSERT INTO redirects SET ua_string = '$ua_string'") or die('Error #10'); mysql_close($conn); ...

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  • is NATURAL JOIN any better than SELECT FROM WHERE in terms of performance ?

    - by ashy_32bit
    Today I got into a debate with my project manager about Cartesian products. He says a 'natural join' is somehow much better than using 'select from where' because the later cause the db engine to internally perform a Cartesian product but the former uses another approach that prevents this. As far as I know, the natural join syntax is not any different in anyway than 'select from where' in terms of performance or meaning, I mean you can use either based on your taste. SELECT * FROM table1,table2 WHERE table1.id=table2.id SELECT * FROM table1 NATURAL JOIN table2 please elaborate about the first query causing a Cartesian product but the second one being somehow more smart

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