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  • Choosing between a union and a boolean condition

    - by bread
    Does this require a UNION? SELECT vend_id, prod_id, prod_price FROM products WHERE prod_price <= 5 UNION SELECT vend_id, prod_id, prod_price FROM products WHERE vend_id IN (1001,1002); Or is it the same if you do it this way? SELECT vend_id, prod_id, prod_price FROM products WHERE prod_price <= 5 OR vend_id IN (1001,1002);

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  • Best way to model Customer <--> Address

    - by Jen
    Every Customer has a physical address and an optional mailing address. What is your preferred way to model this? Option 1. Customer has foreign key to Address Customer (id, phys_address_id, mail_address_id) Address (id, street, city, etc.) Option 2. Customer has one-to-many relationship to Address, which contains a field to describe the address type Customer (id) Address (id, customer_id, address_type, street, city, etc.) Option 3. Address information is de-normalized and stored in Customer Customer (id, phys_street, phys_city, etc. mail_street, mail_city, etc.) One of my overriding goals is to simplify the object-relational mappings, so I'm leaning towards the first approach. What are your thoughts?

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  • How to insert values using Joins in asp.net stroed procedure?

    - by Samba Siva
    CREATE PROC [dbo].[K_HRM_Insert_VehicleAssign] @vehiclename varchar(50), @empname varchar(50), @updatedby varchar(50), @updatedon datetime as begin insert into K_MasterEmpDetails ME inner join K_HRM_Vehicle_Assign VA on VA.[empname+id] = ME.Firstname +' '+ME.Lastname+' - '+ME.kjlid as ME.Employee (VA.vehiclename,ME.Employee,VA.updatedby,VA.updatedon)values(@vehiclename,@empname, @updatedby,getdate()) end I am getting an error near ME...please help me

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  • How to check with PHP does a SQL database already have

    - by Dan Horvat
    I've tried to find the answer to this question but none of the answers fit. I have two databases, one has 15.000.000 entries and I want to extract the necessary data and store it in a much smaller database with around 33.000 entries. Both databases are open at the same time. Or at least they should be. While having the big database open and extracting the entries from it, is it possible to check whether the value already exists in the smaller database? I just need some generic way which checks that.

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  • Stop invalid data in a attribute with foreign key constraint using triggers?

    - by Eternal Learner
    How to specify a trigger which checks if the data inserted into a tables foreign key attribute, actually exists in the references table. If it exist no action should be performed , else the trigger should delete the inserted tuple. Eg: Consider have 2 tables R(A int Primary Key) and S(B int Primary Key , A int Foreign Key References R(A) ) . I have written a trigger like this : Create Trigger DelS BEFORE INSERT ON S FOR EACH ROW BEGIN Delete FROM S where New.A <> ( Select * from R;) ); End; I am sure I am making a mistake while specifying the inner sub query within the Begin and end Blocks of the trigger. My question is how do I make such a trigger ?

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  • Queue access to the database to avoid multiple cache items

    - by MikeJ
    I have a music related ASP.NET web site which caches a lot of static information from the database on the first request. Sometimes, the application is reset and cache is cleared while the application is on heavy load and then all http requests go to the database to retrieve that static data and cache it for other requests. How can I ensure that only one request go to the database and cache the results, so that other request simply read that info from cache and not needlessly retrieve the same info over and over again. Can I use thread locking? For example, can I do something like lock(this) { db access here }?

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  • Best indexing strategy for several varchar columns in Postgres

    - by Corey
    I have a table with 10 columns that need to be searchable (the table itself has about 20 columns). So the user will enter query criteria for at least one of the columns but possibly all ten. All non-empty criteria is then put into an AND condition Suppose the user provided non-empty criteria for column1 and column4 and column8 the query would be: select * from the_table where column1 like '%column1_query%' and column4 like '%column4_query%' and column8 like '%column8_query%' So my question is: am I better off creating 1 index with 10 columns? 10 indexes with 1 column each? Or do I need to find out what sets of columns are queried together frequently and create indexes for them (an index on cols 1,4 and 8 in the case above). If my understanding is correct a single index of 10 columns would only work effectively if all 10 columns are in the condition. Open to any suggestions here, additionally the rowcount of the table is only expected to be around 20-30K rows but I want to make sure any and all searches on the table are fast. Thanks!

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  • Reading from an write-only(OUT) parameter in pl/sql

    - by sqlgrasshopper5
    When I tried writing to an read-only parameter(IN) of a function, Oracle complains with an error. But that is not the case when reading from an write-only(OUT) parameter of a function. Oracle silently allows this without any error. What is the reason for this behaviour?. The following code executes without any assignment happening to "so" variable: create or replace function foo(a OUT number) return number is so number; begin so := a; --no assignment happens here a := 42; dbms_output.put_line('HiYA there'); dbms_output.put_line('VAlue:' || so); return 5; end; / declare somevar number; a number := 6; begin dbms_output.put_line('Before a:'|| a); somevar := foo(a); dbms_output.put_line('After a:' || a); end; / Here's the output I got: Before a:6 HiYA there VAlue: After a:42

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  • MySQL Query involving column names containing math operators

    - by devil_fingers
    I'm a MySQL scrub, and I have asked around and checked around the internet for what I'm sure will turn out to be something obvious, but I'm very frustrated with what I thought would be a very, very simple query not working. So here goes. Please be gentle. Basically, in a large database, some of the column names contain mathematical operators like "/" and "+." (Don't ask, it's not my database, I can't do anything about it). Here is the "essence" of my query (I took out the irrelevant stuff for the sake of this question): SELECT PlayerId, Season, WPA/LI AS WPALI FROM tht.stats_batting_master WHERE Season = "2010" AND teamid > 0 AND PA >= 502 GROUP BY playerid ORDER BY WPALI DESC When I run this, it returns "Unknown column 'LI' in 'field list'," I assume because it sees the "/" in WPA/LI as a division sign. Like I said, I'm sure this is easy enough to work around (it must be given how much this database is used), but I haven't' been able to figure out how. Thanks in advance for any help.

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  • integrating jquery with AJAX using MVC for ddl/html.dropdownlist

    - by needhelp
    the situation: a user on the page in question selects a category from a dropdown which then dynamically populates all the users of that category in a second dropdown beside it. all the data is being retrieved using LinqtoSQL and i was wondering if this can be done a) using html.dropdownlist in a strongly typed view? b) using jquery to trigger the ajax request on selected index change instead of a 'populate' button trigger? sorry i dont have code as what i was trying really wasnt working at all. I am having trouble with how to do it conceptually and programatically! will appreciate any links to examples etc greatly! thanks in advance! EDIT: this is kind of what i was trying to achieve.. first the ViewPage: <script type="text/javascript"> $(document).ready function TypeSearch() { $.getJSON("/Home/Type", null, function(data) { //dont know what to do here }); } </script> <p> <label for="userType">userType:</label> <%= Html.DropDownList("userType") %> <%= Html.ValidationMessage("userType", "*") %> <input type="submit" runat="server" onclick="TypeSearch()" /> <label for="accountNumber">accountNumber:</label> <%= Html.DropDownList("accountNumber") %> <%= Html.ValidationMessage("accountNumber", "*") %> </p> Then home controller action: public ActionResult Type() { string accountType = dropdownvalue; List<Account> accounts = userRep.GetAccountsByType(accountType).ToList(); return Json(accounts); }

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  • How to use SQL trigger to record the affected column's row number

    - by Freeman
    I want to have an 'updateinfo' table in order to record every update/insert/delete operations on another table. In oracle I've written this: CREATE TABLE updateinfo ( rnumber NUMBER(10), tablename VARCHAR2(100 BYTE), action VARCHAR2(100 BYTE), UPDATE_DATE date ) DROP TRIGGER TRI_TABLE; CREATE OR REPLACE TRIGGER TRI_TABLE AFTER DELETE OR INSERT OR UPDATE ON demo REFERENCING NEW AS NEW OLD AS OLD FOR EACH ROW BEGIN if inserting then insert into updateinfo(rnumber,tablename,action,update_date ) values(rownum,'demo', 'insert',sysdate); elsif updating then insert into updateinfo(rnumber,tablename,action,update_date ) values(rownum,'demo', 'update',sysdate); elsif deleting then insert into updateinfo(rnumber,tablename,action,update_date ) values(rownum,'demo', 'delete',sysdate); end if; -- EXCEPTION -- WHEN OTHERS THEN -- Consider logging the error and then re-raise -- RAISE; END TRI_TABLE; but when checking updateinfo, all rnumber column is zero. is there anyway to retrieve the correct row number?

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  • Converting delimited string to multiple values in mysql

    - by epo
    I have a mysql legacy table which contains an client identifier and a list of items, the latter as a comma-delimited string. E.g. "xyz001", "foo,bar,baz". This is legacy stuff and the user insists on being able to edit a comma delimited string. They now have a requirement for a report table with the above broken into separate rows, e.g. "xyz001", "foo" "xyz001", "bar" "xyz001", "baz" Breaking the string into substrings is easily doable and I have written a procedure to do this by creating a separate table, but that requires triggers to deal with deletes, updates and inserts. This query is required rarely (say once a month) but has to be absolutely up to date when it is run, so e.g. the overhead of triggers is not warranted and scheduled tasks to create the table might not be timely enough. Is there any way to write a function to return a table or a set so that I can join the identifier with the individual items on demand?

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  • Double Inner Join generates unexpected error

    - by Itamar Marom
    In my database I have three tables: Users: UserID (Auto Numbering), UserName, UserPassword and a few other unimportant fields. PrivateMessages: MessageID (Auto Numbering), SenderID and a few other fields defining the message content. MessageStatus: MessageID, ReceiverID, MessageWasRead (Boolean) What I need is a query to which I input a user's id and I get all the private messages he has received. In addition, I also need to receive each message's sender UserName. For this I wrote the following query: SELECT Users.*, PrivateMessages.*, MessageStatus.* FROM PrivateMessages INNER JOIN Users ON PrivateMessages.SenderID = Users.UserID INNER JOIN MessageStatus ON PrivateMessages.MessageID = MessageStatus.MessageID WHERE MessageStatus.ReceiverID=[@userid]; But for some reason when I try saving it in my Access database, I get the following error (translated to English by me, since my office is in a different language): Syntax error (missing operator) at expression: "PrivateMessages.SenderID = Users.UserID INNER JOIN MessageStatus ON PrivateMessages.MessageID = MessageStatus.MessageI". Any ideas what could cause this? Thanks.

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  • Which of these queries is preferable?

    - by bread
    I've written the same query as a subquery and a self-join. Is there any obvious argument for one over the other here? SUBQUERY: SELECT prod_id, prod_name FROM products WHERE vend_id = (SELECT vend_id FROM products WHERE prod_id = ‘DTNTR’); SELF-JOIN: SELECT p1.prod_id, p1.prod_name FROM products p1, products p2 WHERE p1.vend_id = p2.vend_id AND p2.prod_id = ‘DTNTR’;

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  • SqlException: Login failed for user

    - by Younes
    I use a dbml for my Data Access Layer to provide the data that i need in my app. When i connect from the server explorer everything seems fine. I choose to use my windows authentication and the connection test shows everything works just fine. When i Build my solution and run it on my IIS it says that i'm using a login that is not working. How to solve this issue?

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  • Ways to implement tags - pros and cons of each

    - by bobobobo
    Related Using SO as an example, what is the most sensible way to manage tags if you anticipate they will change often? Way 1: Seriously denormalized (comma delimited) table posts +--------+-----------------+ | postId | tags | +--------+-----------------+ | 1 | c++,search,code | Here tags are comma delimited. Pros: Tags are retrieved at once with a single select query. Updating tags is simple. Easy and cheap to update. Cons: Extra parsing on tag retrieval, difficult to count how many posts use which tags. (alternatively, if limited to something like 5 tags) table posts +--------+-------+-------+-------+-------+-------+ | postId | tag_1 | tag_2 | tag_3 | tag_4 | tag_5 | +--------+-------+-------+-------+-------+-------+ | 1 | c++ |search | code | | | Way 2: "Slightly normalized" (separate table, no intersection) table posts +--------+-------------------+ | postId | title | +--------+-------------------+ | 1 | How do u tag? | table taggings +--------+---------+ | postId | tagName | +--------+---------+ | 1 | C++ | | 1 | search | Pros: Easy to see tag counts (count(*) from taggings where tagName='C++'). Cons: tagName will likely be repeated many, many times. Way 3: The cool kid's (normalized with intersection table) table posts +--------+---------------------------------------+ | postId | title | +--------+---------------------------------------+ | 1 | Why is a raven like a writing desk? | table tags +--------+---------+ | tagId | tagName | +--------+---------+ | 1 | C++ | | 2 | search | | 3 | foofle | table taggings +--------+---------+ | postId | tagId | +--------+---------+ | 1 | 1 | | 1 | 2 | | 1 | 3 | Pros: No repeating tag names. More girls will like you. Cons: More expensive to change tags than way #1.

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  • Best method to search hierarchical data

    - by WDuffy
    I'm looking at building a facility which allows querying for data with hierarchical filtering. I have a few ideas how I'm going to go about it but was wondering if there are any recommendations or suggestions that might be more efficient. As an example imagine that a user is searching for a job. The job areas would be as follows. 1: Scotland 2: --- West Central 3: ------ Glasgow 4: ------ Etc 5: --- North East 6: ------ Ayrshire 7: ------ Etc A user can search specific (i.e. Glasgow) or in a larger area (i.e. Scotland). The two approaches I am considering are: keep a note of children in the database for each record (i.e. cat 1 would have 2, 3, 4 in its children field) and query against that record with a SELECT * FROM Jobs WHERE Category IN Areas.childrenField. Use a recursive function to find all results who have a relation to the selected area. The problems I see from both are: Holding this data in the db will mean having to keep track of all changes to structure. Recursion is slow and inefficent. Any ideas, suggestion or recommendations on the best approach? I'm using C# ASP.NET with MSSQL 2005 DB.

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  • jpa join query on a subclass

    - by Brian
    I have the following relationships in JPA (hibernate). Object X has two subclasses, Y and Z. Object A has a manyToOne relationship to object X. (Note, this is a one-sided relationship so object X cannot see object A). Now, I want to get the max value of a column in object A, but only where the relationship is of a specific subtype, ie...Y. So, that equates to...get the max value of column1 in object A, across all instances of A where they have a relationship with Y. Is this possible? I'm a bit lost as how to query it. I was thinking of something like: String query = "SELECT MAX(a.columnName) FROM A a join a.x; Query query = super.entityManager.createQuery(query); query.execute(); However that doesn't take account of the subclass of X...so I'm a bit lost. Any help would be much appreciated.

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  • PgJDBC: "no suitable driver found" when following tutorial, why?

    - by Celeritas
    I'm writing a Java program that queries a PostgreSQL database. I'm following this example and have trouble here: connection = DriverManager.getConnection( "jdbc:postgresql://127.0.0.1:5432/testdb", "mkyong", "123456"); According to the JavaDoc for DriverManager the first string is "a database url of the form jdbc:subprotocol:subname. When I connect to the server I type in psql -h dataserv.abc.company.com -d app -U emp24 and give the password qwe123 (for example sake). What should the first argument of getConnection be? I've tried connection = DriverManager.getConnection( "jdbc:postgresql://dataserv.abc.company.com", "emp24", "qwe123"); and get the run time error: no suitable driver found. I've download JDBC4 Postgresql Driver, Version 9.2-1000.

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  • Why is this postgresql query so slow?

    - by user315975
    I'm no database expert, but I have enough knowledge to get myself into trouble, as is the case here. This query SELECT DISTINCT p.* FROM points p, areas a, contacts c WHERE ( p.latitude > 43.6511659465 AND p.latitude < 43.6711659465 AND p.longitude > -79.4677941889 AND p.longitude < -79.4477941889) AND p.resource_type = 'Contact' AND c.user_id = 6 is extremely slow. The points table has fewer than 2000 records, but it takes about 8 seconds to execute. There are indexes on the latitude and longitude columns. Removing the clause concering the resource_type and user_id make no difference. The latitude and longitude fields are both formatted as number(15,10) -- I need the precision for some calculations. There are many, many other queries in this project where points are compared, but no execution time problems. What's going on?

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  • How to return a message from my repository class to my controller and then to my view in asp.net-mvc

    - by Pandiya Chendur
    I use this for checking an existing emailId in my table and inserting it...It works fine how to show message to user when he tries to register with an existing mailId.... if (!taxidb.Registrations.Where(u => u.EmailId == reg.EmailId).Any()) { taxidb.Registrations.InsertOnSubmit(reg); taxidb.SubmitChanges(); } and my controller has this, RegistrationBO reg = new RegistrationBO(); reg.UserName = collection["UserName"]; reg.OrgName = collection["OrgName"]; reg.Address = collection["Address"]; reg.EmailId = collection["EmailId"]; reg.Password = collection["Password"]; reg.CreatedDate = System.DateTime.Now; reg.IsDeleted = Convert.ToByte(0); regrep.registerUser(reg); Any sugesstion how to show "EmailID" already exists to the user with asp.net mvc...

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