partition table - Page 539

SQL Query to retrieve highest item up to a point in a group

- by James

The best way of describing this is I have a table of people with their names and ages. Assume that people with the same surname are from the same family. I need a query in oracle which will retrieve a list of the oldest person in each family, but not older than a certain age. Table: person name surname age =============================== James Smith 23 Sarah Powell 17 Barry Smith 31 Mark Smith 35 Mary Smith 18 Bob Powell 30 How do I retrieve the oldest person in each family under 30? Results I'm after name surname age =============================== James Smith 23 Sarah Powell 17

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Using MS Moles with datacontext and stored procedures without using a Connection string.

- by Brian

I have just begun to work with MS Moles for testing and I have followed the idea/pattern in which jcollum(thanks) uses a Mole for a table in this stackoverflow question here. But I am having a problem as I do not want to have to pass a connection string when I use the datasource as such: using (TheDataContext dataContext = new TheDataContext(myConnectionString)) { dataContext.ExecuteStoredprocedure(value, ref ValueExists); } I really like the fact that I just need to mole the table and everything else is done for me. I realize I could just mole the ExecuteStoredProcedure method, but I am wondering if I could just somehow avoid the sql exception I am getting here when I do not pass in the connection string. Or, if I there is a better way to do this? Therefore, does anyone have a solution so that I can avoid placing in the connection string? Thanks in advance.

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JPA @ManyToOne and composite PK

- by Fleuri F

Good Morning, I am working on project using JPA. I need to use a @ManyToOne mapping on a class that has three primary keys. You can find the errors and the classes after this. If anyone has an idea! Thanks in advance! FF javax.persistence.PersistenceException: No Persistence provider for EntityManager named JTA_pacePersistence: Provider named oracle.toplink.essentials.PersistenceProvider threw unexpected exception at create EntityManagerFactory: javax.persistence.PersistenceException javax.persistence.PersistenceException: Exception [TOPLINK-28018] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.EntityManagerSetupException Exception Description: predeploy for PersistenceUnit [JTA_pacePersistence] failed. Internal Exception: Exception [TOPLINK-7220] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.ValidationException Exception Description: The @JoinColumns on the annotated element [private java.util.Set isd.pacepersistence.common.Action.permissions] from the entity class [class isd.pacepersistence.common.Action] is incomplete. When the source entity class uses a composite primary key, a @JoinColumn must be specified for each join column using the @JoinColumns. Both the name and the referenceColumnName elements must be specified in each such @JoinColumn. at oracle.toplink.essentials.internal.ejb.cmp3.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:643) at oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider.createEntityManagerFactory(EntityManagerFactoryProvider.java:196) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:110) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83) at isd.pacepersistence.common.DataMapper.(Unknown Source) at isd.pacepersistence.server.MainServlet.getDebugCase(Unknown Source) at isd.pacepersistence.server.MainServlet.doGet(Unknown Source) at javax.servlet.http.HttpServlet.service(HttpServlet.java:718) at javax.servlet.http.HttpServlet.service(HttpServlet.java:831) at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:411) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:290) at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:271) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:202) There is the source code of my classes : Action : @Entity @Table(name="action") public class Action { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private int num; @ManyToOne(cascade= { CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH }) @JoinColumn(name="domain_num") private Domain domain; private String name; private String description; @OneToMany @JoinTable(name="permission", joinColumns= { @JoinColumn(name="action_num", referencedColumnName="action_num", nullable=false, updatable=false) }, inverseJoinColumns= { @JoinColumn(name="num") }) private Set<Permission> permissions; public Action() { } Permission : @SuppressWarnings("serial") @Entity @Table(name="permission") public class Permission implements Serializable { @EmbeddedId private PermissionPK primaryKey; @ManyToOne @JoinColumn(name="action_num", insertable=false, updatable=false) private Action action; @ManyToOne @JoinColumn(name="entity_num", insertable=false, updatable=false) private isd.pacepersistence.common.Entity entity; @ManyToOne @JoinColumn(name="class_num", insertable=false, updatable=false) private Clazz clazz; private String kondition; public Permission() { } PermissionPK : @SuppressWarnings("serial") @Entity @Table(name="permission") public class Permission implements Serializable { @EmbeddedId private PermissionPK primaryKey; @ManyToOne @JoinColumn(name="action_num", insertable=false, updatable=false) private Action action; @ManyToOne @JoinColumn(name="entity_num", insertable=false, updatable=false) private isd.pacepersistence.common.Entity entity; @ManyToOne @JoinColumn(name="class_num", insertable=false, updatable=false) private Clazz clazz; private String kondition; public Permission() { }

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how do i load a csv file in rails from a migrate usiing load data local infile ?

- by Chris Drappier

Hi All, I have my csv file in my public folder, and i'm trying to load it from a migration, but I get a file not found error using this script : ActiveRecord::Base.connection.execute( "load data local infile '#{RAILS_ROOT}/public/muds_variables.csv' into table muds_variables " + "fields terminated by ',' " + "lines terminated by '\n' " + "(variable_name, definition)") I've checked and re-checked the file path, and that's definitely where it lives, I've also tried it just using the file name without any of the path, and a few other combos, but I can't make it work :(. can anyone help me out with this? here's the error : Mysql::Error: File '/home/chris/rails_projects/muds/public/muds_variables.csv' not found (Errcode: 2): load data local infile '/home/chris/rails_projects/muds/public/muds_variables.csv' into table muds_variables fields terminated by ',' lines terminated by ' ' (variable_name, definition) -C

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Visualforce dataTable: is there a way to stop it from rendering cellpadding attribute?

- by codeulike

In Visualforce, I'm using an <apex:dataTable> component as follows: <apex:dataTable value="{!Qualifications}" var="qual" styleClass="cv_table" >  ... and then I'm using CSS to style the table, via the class name. Trouble is, VisualForce renders HTML like this: <table class="cv_table" id="j_id0:j_id26" border="0" cellpadding="0" cellspacing="0">  The class attribute is there as I wanted, but there's also cellpadding and cellspacing specified, that interfere with my CSS. Is there a way to stop Visualforce from rendering the cellpadding and cellspacing attributes for an <apex:dataTable>?

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Implementing EAV pattern with Hibernate for User -> Settings relationship

- by Trevor

I'm trying to setup a simple EAV pattern in my web app using Java/Spring MVC and Hibernate. I can't seem to figure out the magic behind the hibernate XML setup for this scenario. My database table "SETUP" has three columns: user_id (FK) setup_item setup_value The database composite key is made up of user_id | setup_item Here's the Setup.java class: public class Setup implements CommonFormElements, Serializable { private Map data = new HashMap(); private String saveAction; private Integer speciesNamingList; private User user; Logger log = LoggerFactory.getLogger(Setup.class); public String getSaveAction() { return saveAction; } public void setSaveAction(String action) { this.saveAction = action; } public User getUser() { return user; } public void setUser(User user) { this.user = user; } public Integer getSpeciesNamingList() { return speciesNamingList; } public void setSpeciesNamingList(Integer speciesNamingList) { this.speciesNamingList = speciesNamingList; } public Map getData() { return data; } public void setData(Map data) { this.data = data; } } My problem with the Hibernate setup, is that I can't seem to figure out how to map out the fact that a foreign key and the key of a map will construct the composite key of the table... this is due to a lack of experience using Hibernate. Here's my initial attempt at getting this to work: <composite-id> <key-many-to-one foreign-key="id" name="user" column="user_id" class="Business.User"> <meta attribute="use-in-equals">true</meta> </key-many-to-one> </composite-id> <map lazy="false" name="data" table="setup"> <key column="user_id" property-ref="user"/> <composite-map-key class="Command.Setup"> <key-property name="data" column="setup_item" type="string"/> </composite-map-key> <element column="setup_value" not-null="true" type="string"/> </map> Any insight into how to properly map this common scenario would be most appreciated!

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Add comma-separated value of grouped rows to existing query

- by Peter Lang

I've got a view for reports, that looks something like this: SELECT a.id, a.value1, a.value2, b.value1, /* (+50 more such columns)*/ FROM a JOIN b ON (b.id = a.b_id) JOIN c ON (c.id = b.c_id) LEFT JOIN d ON (d.id = b.d_id) LEFT JOIN e ON (e.id = d.e_id) /* (+10 more inner/left joins) */ It joins quite a few tables and returns lots of columns, but indexes are in place and performance is fine. Now I want to add another column to the result, showing comma-separated values ordered by value from table y outer joined via intersection table x if a.value3 IS NULL, else take a.value3 To comma-separate the grouped values I use Tom Kyte's stragg, could use COLLECT later. Pseudo-code for the SELECT would look like that: SELECT xx.id, COALESCE( a.value3, stragg( xx.val ) ) value3 FROM ( SELECT x.id, y.val FROM x WHERE x.a_id = a.id JOIN y ON ( y.id = x.y_id ) ORDER BY y.val ASC ) xx GROUP BY xx.id What is the best way to do it? Any tips?

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Databound Checkbox list with textboxes in a webform

- by zSysop

Hi all, I'm having trouble coming up with a solution for the following problem and i was wondering if someone here would help me out. I need to pull a list of supplies from a db table and list them along with two textboxes (one for quantity, and another for manufacturer) so the list would look something like this. checkbox for supply 1 | Quantity | Manufacturer checkbox for supply 2 | Quantity | Manufacturer .. I also need to store all of the checked items in a db table. I'm not sure how i should go about doing this. I've heard some talk about a repeater control being useful but i've not come across any examples that do this type of thing. Thanks in advance

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asp.net mvc textbox date format

- by maxxxee

My form contains a textbox for date input. When submitted the data is used to add a row to the table. The view is strongly typed to the table. The problem is that the database server is configured with US date format. But the users need to use UK date format in the textbox. When users enter uk date format error is thrown. The database server configuration cannot be changed. So what can be done so that users can enter date in uk format?

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SQL Query - Count column values separately

- by user575535

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HP ENVY TouchSmart 15t-j000 Quad Edition + custom mSata Plextor M5M 64GB SSD

- by Akash Ramani

The ssd did not come along with the laptop, so i bought one myself and physically installed it. I've booted into Ubuntu from a USB drive and my goal is to install / and /home in the SSD. (because most of the actual media exists on the HDD) The only problem is i'm unable to detect the SSD while configuring the partitions. I know the SSD is not the problem because it recognizes in a different laptop. I've followed the instructions shown in https://help.ubuntu.com/community/UEFI but that still doesn't help in identifying the SSD partition. Any help would be appreciated. (p.s: I'm wondering if i have to prepare the SSD through windows or something like that)

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OT: US Banks: Bank Routing Number and BIC/SWIFT

- by Konerak

I know it is a bit offtopic, but I've been having a hard time finding more information to this question, and since this site is visited by a lot of people from the United States, you guys might know/find the answer more easily. Banks in europe each have a SWIFT Number, while US Banks use Routing Numbers. This leads to following questions: Does each bank in the US also carry a BIC number? (SWIFT) Is there a 1-1 relationship between BIC and SWIFT? Is there a list of these numbers somewhere? (background information: we're adding international payments to our bookkeeping application. Users can add international suppliers, but my boss prefered not to change the current supplier table but to have the ROUTING NUMBER in another table, with as PK the BIC. I'm wondering if BIC is a valid choice, or if it should just be BANK ACCOUNT NUMBER.)

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Column locking in innodb?

- by ming yeow

I know this sounds weird, but apparently one of my columns is locked. select * from table where type_id = 1 and updated_at < '2010-03-14' limit 1; select * from table where type_id = 3 and updated_at < '2010-03-14' limit 10; the first one would not finish running even in a few hours, while the second one completes smoothly. the only difference is the type_id between the 2 queries. a bit of background, the first statement screwed up before which i had to kill manually. Thanks in advance for your help - i have an urgent data job to finish, and this problem is driving me crazy

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Racket: change dotted pair to list

- by user2963128

I have a program that recursively calls a hashtable and prints out data from it. Unfortunately my hashtable seems to be saving data as dotted pairs so when I call the hashtable I get an error saying that there is no data for it because its tryign to search the hashtable for a dotted pair instead of a list. Is there an easy way to make the dotted pair into a regular list? IE im getting '("was" . "beginning") instead of '("was" "beginning") Is there a way to change this without re-writing how my hashtable store stuff? im using the let function to set a variable to this and then calling another function based on this variable (let ((data ( list-ref(hash-ref Ngram-table key) (random (length (hash-ref Ngram-table key)))))) is there a way to make the value stored in data just a list like this '("var1" "var2") instead of a dotted pair? edit: im getting dotted pairs because im using let to set data to the part of the hashtable's key and one of the elements in that hash.

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Advice on displaying and allowing editing of data using ASP.NET MVC?

- by Remnant

I am embarking upon my first ASP.NET MVC project and I would like to get some input on possible ways to display database data and general best practice. In short, the body of my webpage will show data from my database in a table like format, with each table row showing similar data. For example: Name Age Position Date Joined Jon Smith 23 Striker 18th Mar 2005 John Doe 38 Defender 3rd Jan 1988 In terms of functionality, primarily I’d like to give the user the ability to edit the data and, after the edit, commit the edit to the database and refresh the view.The reason I want to refresh the view is because the data is date ordered and I will need to re-sort if the user edits a date field. My main question is what architecture / tools would be best suited to this fulfil my requirements at a high level? From the research I have done so far my initial conclusions were: ADO.NET for data retrieval. This is something I have used before and feel comfortable with. I like the look of LINQ to SQL but don’t want to make the learning curve any steeper for my first outing into MVC land just yet. Partial Views to create a template and then iterate through a datatable that I have pulled back from my database model. jQuery to allow the user to edit data in the table, error check edited data entries etc. Also, my intial view was that caching the data would not be a key requirement here. The only field a user will be able to update is the field and, if they do, I will need to commit that data to the database immediately and then refresh the view (as the data is date sorted). Any thoughts on this? Alternatively, I have seen some jQuery plug-ins that emulate a datagrid and provide associated functionality. My first thoughts are that I do not need all the functionality that comes with these plug-ins (e.g. zebra striping, ability to sort by column using sort glyph in column headers etc .) and I don’t really see any benefit to this over and above the solution I have outlined above. Again, is there reason to reconsider this view? Finally, when a user edits a date , I will need to refresh the view. In order to do this I had been reading about Html.RenderAction and this seemed like it may be a better option than using Partial Views as I can incorporate application logic into the action method. Am I right to consider Html.RenderAction or have I misunderstood its usage? Hope this post is clear and not too long. I did consider separate posts for each topic (e.g. Partial View vs. Html.RenderAction, when to use jQury datagrid plug-in) but it feels like these issues are so intertwined that they need to be dealt with in contect of each other. Thanks

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Purple Screen then Black Screen while Booting from CD or Windows Install

- by Tyler

Whenever I try to run Ubuntu from my internal CD drive, I see this screen minus the Ubuntu Text: Then the screen goes black, not even the internal light stays on. Sometimes it restarts itself, other times the black screen is indefinite until I restart the laptop myself. I'm on an HP Quad-Core AMD A8-3500M APU with 8 GB RAM and a Radeon AMD 6620g Discrete-Graphics Card. (HP dv6-6145dx) This is my first time using Linux, I am not too technically-inclined so any simplification would be welcomed. I am good at following technical instructions though which is how I was able to partition my hard drive and change the boot order to allow the internal CD drive first. Thanks in advance!

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Removing last word from FOREACH loop

- by Stoosh

I'm building a basic function, which builds out Mysql WHERE clauses based on how many are in the array. $array = array('id' => '3', 'name' => 'roger'); $sql = "SELECT * FROM table WHERE "; foreach ($array as $k => $v) { $sql .= $k . ' = ' . $v . ' AND '; } which will output SELECT * FROM table WHERE id = 3 AND name = roger AND However obviously I don't want that last AND, how do I go about removing it from the string? Thanks

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Grub bootloader goes fail to boot in dual boot system after installing Ubuntu 12.10

- by K.K Patel

I had 12.04 with my dual boot system. Yesterday I downloaded Ubuntu 12.10 make bootable USB and choose Upgrade option in Installer. After installation Grub failed to boot my machine. I tried following to fix grub bootloder . Same problem I fixed with Ubuntu 12.04 using live USB but this solution not work for Ubuntu 12.10. Now coming at exactly where this solution goes fail. I followed this steps after booting Live USB and opening terminal. 1) sudo fdisk -l to see where Linux is installed 2) sudo mount /dev/sda9 /mnt where sda9 is my linux partition 3) sudo mount /dev/sda9 /mnt/boot 4) sudo mount --bind /dev /mnt/dev 5) sudo chroot /mnt (No problems with this steps done perfectly) 6) grub-install /dev/sda when I type command I got error that source_dir doesn't exist Please specify --target or --directory How can I solve this ?

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SQL 2003 Distance Latitude Longitude

- by J.Hendrix

I have a table full of Dealers along with their latitude and longitude. I am trying to determine the top n closest dealers to any given lat and lon. I already have the function to calculate distance between locations, but I want to do as few calculations as possible (my table can contain many thousands of entries). Currently I have to calculate the distance for each entry then sort them. Is there any way to sort before I do the calculation to improve performance? This question is good, but I will not always know my range. Should I just pick an arbitrarily high range then refine my results? I am thankful for any help the community can offer. declare @Lat real declare @lon real Set @lat = 41.05 Set @lon = -73.53 SELECT top 10 MemberID, Address1, City, State, Zip, Phone, Lat, Lon, (SELECT fun_DistanceLatLon] (@Lat,@lon,Lat,Lon)) as mDistance --Calculate distance FROM Dealers Order by (SELECT fun_DistanceLatLon] (@Lat,@lon,Lat,Lon))

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Ubuntu 13.10 software raid

- by Piotr Belniak

I had already Ubuntu OS installed on my desktop PC, where the software RAID 5 is configured ( 3 partitions /, swap and home ). This system was upgraded from the 11.04 till 13.04, it was quite messy, so I decided to install fresh system on existing partitions. 1st of all i found that there is no alternate version of the installer ( which i used to create previous installation ), so i stared with the regular image. I installed mdadm tools, assemble the partitions - fdisk are showing them properly - so i'm starting the installation - and everything i going fine until the GRUB instalation - this part fails - regardless of which partition i use as a target. From the other hand, neither OpenSUse and Ubuntu 12.04 alternate does not have any problems with installing the GRUB - on this configuration, unfortunatelly Ubuntu 12.04 - 12.10 upgrade is failing bacause of some Xorg issues ;(. Maybe someone has an experience with installation of ubuntu 13.10 GRUB on the RAID 5 partitions - and could give me a hint, how to solve my problem. Thanks in advance, Piotr

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How can I transfer output that appears on the console and format it so that it appears on a web page

- by lojayna

package collabsoft.backlog_reports.c4; import java.sql.CallableStatement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; //import collabsoft.backlog_reports.c4.Report; public class Report { private Connection con; public Report(){ connectUsingJDBC(); } public static void main(String args[]){ Report dc = new Report(); dc.reviewMeeting(6, 8, 10); dc.createReport("dede",100); //dc.viewReport(100); // dc.custRent(3344,123,22,11-11-2009); } /** the following method is used to connect to the database **/ public void connectUsingJDBC() { // This is the name of the ODBC data source String dataSourceName = "Simple_DB"; try { // loading the driver in the memory Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); // This is the connection URL String dbURL = "jdbc:odbc:" + dataSourceName; con = DriverManager.getConnection("jdbc:mysql://localhost:3306/Collabsoft","root",""); // This line is used to print the name of the driver and it would throw an exception if a problem occured System.out.println("User connected using driver: " + con.getMetaData().getDriverName()); //Addcustomer(con,1111,"aaa","aaa","aa","aam","111","2222","111"); //rentedMovies(con); //executePreparedStatement(con); //executeCallableStatement(con); //executeBatch(con); } catch (Exception e) { e.printStackTrace(); } } /** *this code is to link the SQL code with the java for the task *as an admin I should be able to create a report of a review meeting including notes, tasks and users *i will take the task id and user id and note id that will be needed to be added in the review *meeting report and i will display the information related to these ida **/ public void reviewMeeting(int taskID, int userID, int noteID)// law el proc bt return table { try{ CallableStatement callableStatement = con.prepareCall("{CALL report_review_meeting(?,?,?)}"); callableStatement.setInt(1,taskID); callableStatement.setInt(2,userID); callableStatement.setInt(3,noteID); ResultSet resultSet = callableStatement.executeQuery(); // or executeupdate() or updateQuery ResultSetMetaData rsm = resultSet.getMetaData(); int numOfColumns = rsm.getColumnCount(); System.out.println("lojayna"); while (resultSet.next()) { System.out.println("New Row:"); for (int i = 1; i <= numOfColumns; i++) System.out.print(rsm.getColumnName(i) + ": " + resultSet.getObject(i) + " "); System.out.println(); } } catch(Exception e) { System.out.println("E"); } } ////////////////////////////////// ///////////////////////////////// public void allproject(int projID)// law el proc bt return table { try{ CallableStatement callableStatement = con.prepareCall("{CALL all_project(?)}"); callableStatement.setInt(1,projID); //callableStatement.setInt(2,userID); //callableStatement.setInt(3,noteID); ResultSet resultSet = callableStatement.executeQuery(); // or executeupdate() or updateQuery ResultSetMetaData rsm = resultSet.getMetaData(); int numOfColumns = rsm.getColumnCount(); System.out.println("lojayna"); while (resultSet.next()) { System.out.println("New Row:"); for (int i = 1; i <= numOfColumns; i++) System.out.print(rsm.getColumnName(i) + ": " + resultSet.getObject(i) + " "); System.out.println(); } } catch(Exception e) { System.out.println("E"); } } /////////////////////////////// /** * here i take the event id and i take a string report and then * i relate the report with the event **/ public void createReport(String report,int E_ID )// law el proc bt return table { try{ Statement st = con.createStatement(); st.executeUpdate("UPDATE e_vent SET e_vent.report=report WHERE e_vent.E_ID= E_ID;"); /* CallableStatement callableStatement = con.prepareCall("{CALL Create_report(?,?)}"); callableStatement.setString(1,report); callableStatement.setInt(2,E_ID); ResultSet resultSet = callableStatement.executeQuery(); // or executeupdate() or updateQuery ResultSetMetaData rsm = resultSet.getMetaData(); int numOfColumns = rsm.getColumnCount(); System.out.println("lojayna"); while (resultSet.next()) { System.out.println("New Row:"); for (int i = 1; i <= numOfColumns; i++) System.out.print(rsm.getColumnName(i) + ": " + resultSet.getObject(i) + " "); System.out.println(); }*/ } catch(Exception e) { System.out.println("E"); System.out.println(e); } } /** *in the following method i view the report of the event having the ID eventID **/ public void viewReport(int eventID)// law el proc bt return table { try{ CallableStatement callableStatement = con.prepareCall("{CALL view_report(?)}"); callableStatement.setInt(1,eventID); ResultSet resultSet = callableStatement.executeQuery(); // or executeupdate() or updateQuery ResultSetMetaData rsm = resultSet.getMetaData(); int numOfColumns = rsm.getColumnCount(); System.out.println("lojayna"); while (resultSet.next()) { System.out.println("New Row:"); for (int i = 1; i <= numOfColumns; i++) System.out.print(rsm.getColumnName(i) + ": " + resultSet.getObject(i) + " "); System.out.println(); } } catch(Exception e) { System.out.println("E"); } } } // the result of these methods is being showed on the console , i am using WIcket and i want it 2 be showed on the web how is that done ?!

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mysql first record retrieval

- by Sammy

While very easy to do in Perl or PHP, I cannot figure how to use mysql only to extract the first unique occurence of a record. For example, given the following table: Name Date Time Sale John 2010-09-12 10:22:22 500 Bill 2010-08-12 09:22:37 2000 John 2010-09-13 10:22:22 500 Sue 2010-09-01 09:07:21 1000 Bill 2010-07-25 11:23:23 2000 Sue 2010-06-24 13:23:45 1000 I would like to extract the first record for each individual in asc time order. After sorting the table is ascending time order, I need to extract the first unique record by name. So the output would be : Name Date Time Sale John 2010-09-12 10:22:22 500 Bill 2010-07-25 11:23:23 2000 Sue 2010-06-24 13:23:45 1000 Is this doable in an easy fashion with mySQL? Thanks, Sammy

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MySQL index cardinality - performance vs storage efficiency

- by Sean

Say you have a MySQL 5.0 MyISAM table with 100 million rows, with one index (other than primary key) on two integer columns. From my admittedly poor understanding of B-tree structure, I believe that a lower cardinality means the storage efficiency of the index is better, because there are less parent nodes. Whereas a higher cardinality means less efficient storage, but faster read performance, because it has to navigate through less branches to get to whatever data it is looking for to narrow down the rows for the query. (Note - by "low" vs "high", I don't mean e.g. 1 million vs 99 million for a 100 million row table. I mean more like 90 million vs 95 million) Is my understanding correct? Related question - How does cardinality affect write performance?

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Display/Edit fields across tables in a Django Form

- by jamida

I have 2 tables/models, which for all practical purposes are the same as the standard Author/Book example, but with the additional restriction that in my application each Author can only write 0 or 1 books. (eg, the ForeignKey field in the Book model is or can be a OneToOneField, and there may be authors who have no corresponding book in the Book table.) I would like to be able to display a form showing multiple books and also show some fields from the corresponding Author table (eg author_name, author_address). I followed the example of the inlineformset and but that doesn't even display the author name in the generated form.

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Asp.Net Login control (Visual Web Dev)

- by craig

This is the code when you take the Login control from the toolbox. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <div> <asp:Login ID="Login1" runat="server" onauthenticate="Login1_Authenticate" BackColor="#F7F7DE" BorderColor="#CCCC99" BorderStyle="Solid" BorderWidth="1px" Font-Names="Verdana" Font-Size="10pt"> <LayoutTemplate> <table border="0" cellpadding="1" cellspacing="0" style="border-collapse:collapse;"> <tr> <td> <table border="0" cellpadding="0"> <tr> <td align="center" colspan="2"> Log In</td> </tr> <tr> <td align="right"> <asp:Label ID="UserNameLabel" runat="server" AssociatedControlID="UserName">User Name:</asp:Label> </td> <td> <asp:TextBox ID="UserName" runat="server" ></asp:TextBox> <asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="UserName" ErrorMessage="User Name is required." ToolTip="User Name is required." ValidationGroup="Login1">*</asp:RequiredFieldValidator> </td> </tr> <tr> <td align="right"> <asp:Label ID="PasswordLabel" runat="server" AssociatedControlID="Password">Password:</asp:Label> </td> <td> <asp:TextBox ID="Password" runat="server" TextMode="Password"></asp:TextBox> <asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="Password" ErrorMessage="Password is required." ToolTip="Password is required." ValidationGroup="Login1">*</asp:RequiredFieldValidator> </td> </tr> <tr> <td colspan="2"> <asp:CheckBox ID="RememberMe" runat="server" Text="Remember me next time." /> </td> </tr> <tr> <td align="center" colspan="2" style="color:Red;"> <asp:Literal ID="FailureText" runat="server" EnableViewState="False"></asp:Literal> </td> </tr> <tr> <td align="right" colspan="2"> <asp:Button ID="LoginButton" runat="server" CommandName="Login" Text="Log In" ValidationGroup="Login1" onclick="LoginButton_Click" /> </td> </tr> </table> </td> </tr> </table> </LayoutTemplate> <TitleTextStyle BackColor="#6B696B" Font-Bold="True" ForeColor="#FFFFFF" /> </asp:Login> </div> </form> </body> </html> Part of my aspx.cs protected void LoginButton_Click(object sender, EventArgs e) { String sUserName = UserName.Text; String sPassword = Password.Text; Error 1 The name 'UserName' does not exist in the current context Error 2 The name 'Password' does not exist in the current context Error 3 'ASP.default_aspx' does not contain a definition for 'Login1_Authenticate' and no extension method 'Login1_Authenticate' accepting a first argument of type 'ASP.default_aspx' could be found (are you missing a using directive or an assembly reference?) What am I doing wrong?

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