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  • How to create reference tables using fluent nhibernate

    - by Akk
    How can i create a 3 table schema from the following model classes. public class Product { public int Id {get; set;} public string Name {get; set;} public IList<Photo> Photos {get; set;} } public class Photo { public int Id {get; set;} public string Path {get; set;} } I want to create the following table structure in the database: Product ------- Id Name ProductPhotos ------------- ProductId (FK Products.Id) PhotoId (FK Photos.Id) Photos ------ Id Path How i can express the above Database Schema using Fluent NHibernate? I could only manage the following the Mapping but this does not get me the 3rd Photo ref table. public class ProductMap : ClassMap<Product> { public CityMap() { Id(x => x.Id); Map(x => x.Name); Table("Products"); HasMany(x => x.Photos).Table("ProductPhotos").KeyColumn("ProductId"); } }

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  • Generic IEqualityComparer

    - by Nettuce
    A generic equality comparer that takes a property expression or a comparison Func public class GenericComparer<T> : IEqualityComparer<T> where T : class         {             private readonly Func<T, T, bool> comparerExpression;             private readonly string propertyName;             public GenericComparer(Func<T, T, bool> comparerExpression)             {                 this.comparerExpression = comparerExpression;             }             public GenericComparer(Expression<Func<T, object>> propertyExpression)             {                 propertyName = (propertyExpression.Body is UnaryExpression ? (MemberExpression)((UnaryExpression)propertyExpression.Body).Operand : (MemberExpression)propertyExpression.Body).Member.Name;             }             public bool Equals(T x, T y)             {                 return comparerExpression == null ? x.GetType().GetProperty(propertyName).GetValue(x, null).Equals(y.GetType().GetProperty(propertyName).GetValue(y, null)) : comparerExpression.Invoke(x, y);             }             public int GetHashCode(T obj)             {                 return obj.ToString().GetHashCode();             }         }

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  • C# : Problem in creating diffrent types of columns in a gridview

    - by Royson
    My windows form application has a grid view control with filename as a default column. User should create a column of following types Text, Number, Currency, Combo Box, Check Box, Radio Button ,Date time type (should display DateTimePicker control) and Hyper Link type. After that i want to pass all rows to next screen for further processing. We can create a column of these types in a grid view but how can i store it in a data table so that i can pass it to next screen. Or should i create a column in a data table and then assign data table to grid view by gridview.DataSource = dt; but can we create a these types of columns in a data table. I am so confused!! Please help me to solve this problem. Thanks

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  • database assignment

    - by eric
    Hi, Given the following table: CREATE TABLE T1 (A INTEGER NOT NULL); CREATE TABLE T3 (A SMALLINT NOT NULL); INSERT T1 VALUES (32768.5); SELECT * FROM T1; INSERT T3 SELECT * FROM T1; SELECT * FROM T3; What is the output of above query? If any error occured please declare the line of it?Explain your answer!

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  • Question on different ways to link tables

    - by dotnetdev
    What is the difference between linking two tables and then the PK is an FK in the other table, but the FK has not got the primary key option (so it does not have the gold key), and having the PK in one table as a PK in another table? Am I right to think that the second option is for a many-to-many relationship? Thanks

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  • update record only works when there is no auto_increment

    - by every_answer_gets_a_point
    i am accessing a mysql table through an odbc connection in excel here is how i am updating the table: With rs .AddNew ' create a new record ' add values to each field in the record .Fields("datapath") = dpath .Fields("analysistime") = atime .Fields("reporttime") = rtime .Fields("lastcalib") = lcalib .Fields("analystname") = aname .Fields("reportname") = rname .Fields("batchstate") = "bstate" .Fields("instrument") = "NA" .Update ' stores the new record End With when the schema of the table is this, updating it works: create table batchinfo(datapath text,analysistime text,reporttime text,lastcalib text,analystname text, reportname text, batchstate text, instrument text); but when i have auto_increment in there it does not work: CREATE TABLE batchinfo ( rowid int(11) NOT NULL AUTO_INCREMENT, datapath text, analysistime text, reporttime text, lastcalib text, analystname text, reportname text, batchstate text, instrument text, PRIMARY KEY (rowid) ) ENGINE=InnoDB AUTO_INCREMENT=67 DEFAULT CHARSET=latin1 has anyone experienced a problem like this where updating does not work when there is an auto_increment field involved? connection string: Private Sub ConnectDB() Set oConn = New ADODB.Connection oConn.Open "DRIVER={MySQL ODBC 5.1 Driver};" & _ "SERVER=localhost;" & _ "DATABASE=employees;" & _ "USER=root;" & _ "PASSWORD=pas;" & _ "Option=3" End Sub also here's the rs.open: rs.Open "batchinfo", oConn, adOpenKeyset, adLockOptimistic, adCmdTable

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  • [SQL] Getting the sum of several columns from two tables

    - by romaintaz
    I want to get the sum of several columns from 2 different tables (these tables share the same structure). If I only consider one table, I would write this kind of query: SELECT MONTH_REF, SUM(amount1), SUM(amount2) FROM T_FOO WHERE seller = XXX GROUP BY MONTH_REF; However, I would like to also work with the data from the table T_BAR, and then have a select query that return the following columns: MONTH_REF SUM(T_FOO.amount1) + SUM(T_BAR.amount1) SUM(T_FOO.amount2) + SUM(T_BAR.amount2) everything grouped by the value of MONTH_REF. Note that a record for a given MONTH_REF can be found in one table but not in the other table. In this case, I would like to get the sum of T_FOO.amount1 + 0 (or 0 + T_BAR.amount1). How can I write my SQL query to get this information? For information, my database is Oracle 10g.

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  • LAbeling with Percentage in R plot

    - by Libo Cannici
    Hi I have made this function that takes a table and prepare the label for a barplot prepare_labels <- function(ft){ labs <- ft labs <- paste(labs, "\n", sep="") labs <- paste(labs, round(prop.table(ft)*100,2), sep="") labs <- paste(labs, "%", sep="") return(labs) } It actually works fine, but is there any better way to write that function, the above code looks ugly and I want to write beautiful code :-) ex: ft <- table(mydata$phone_partner_products) prepare_labels(ft) [1] "3752\n34.09%" "226\n2.05%" "2907\n26.41%" "1404\n12.76%" "1653\n15.02%" [6] "1065\n9.68%"

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  • SQL update statement to change the value of a field and not replace it

    - by wzzrd
    I'm in the process of migrating some databases. I have this table that has a couple of hundred rows, and has a filename column. To each record in this table, the filename column needs to be altered and part of a path needs to be prepended to the value that is in that field. The table is like: | 1 | filename1 | | 2 | filename2 | and needs to become: | 1 | path/filename1 | | 2 | path/filename2 | I am not an SQL guru, but I know the basics. This eludes me though. Is there a way to do something like: update table set filename = 'path/' + filename where id = 1;

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  • SQL: find entries in 1:n relation that don't comply with condition spanning multiple rows

    - by milianw
    I'm trying to optimize SQL queries in Akonadi and came across the following problem that is apparently not easy to solve with SQL, at least for me: Assume the following table structure (should work in SQLite, PostgreSQL, MySQL): CREATE TABLE a ( a_id INT PRIMARY KEY ); INSERT INTO a (a_id) VALUES (1), (2), (3), (4); CREATE TABLE b ( b_id INT PRIMARY KEY, a_id INT, name VARCHAR(255) NOT NULL ); INSERT INTO b (b_id, a_id, name) VALUES (1, 1, 'foo'), (2, 1, 'bar'), (3, 1, 'asdf'), (4, 2, 'foo'), (5, 2, 'bar'), (6, 3, 'foo'); Now my problem is to find entries in a that are missing name entries in table b. E.g. I need to make sure each entry in a has at least the name entries "foo" and "bar" in table b. Hence the query should return something similar to: a_id = 3 is missing name "bar" a_id = 4 is missing name "foo" and "bar" Since both tables are potentially huge in Akonadi, performance is of utmost importance. One solution in MySQL would be: SELECT a.a_id, CONCAT('|', GROUP_CONCAT(name ORDER BY NAME ASC SEPARATOR '|'), '|') as names FROM a LEFT JOIN b USING( a_id ) GROUP BY a.a_id HAVING names IS NULL OR names NOT LIKE '%|bar|foo|%'; I have yet to measure the performance tomorrow, but severly doubt it's any fast for tens of thousand of entries in a and thrice as many in b. Furthermore we want to support SQLite and PostgreSQL where to my knowledge the GROUP_CONCAT function is not available. Thanks, good night.

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  • What's the best way to store custom objects in relational database?

    - by user342610
    I have my objects with their properties. Objects could change their structure: properties may be added/removed/changed. Objects could be absolutely dropped. So object's metadata (description, classes, call them like you want :) )could be changed. The database should store objects schemas and instances of these objects. What's the best way to organise a relational database structure to store data mentioned above? Currently I see only two ways: 1) Store objects schemas in a few tables: schema general data,schema properties, possible properties types. Store instances in their tables: instance general data, a few tables - per each type from possible properties types table to store instance properties data. And so on. 2) store objects schemas like in p1 but store instances like XML files in one table: one table for general instance info and one table with instance XML. please, don't ask why/for what I need this. Just need to store custom objects and DB should work fast :)

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  • Multiple column foreign key contraints

    - by eugene4968
    I want to setup table constraints for the following scenario and I’m not sure how to do it or if it’s even possible in SQL Server 2005. I have three tables A,B,C. C is a child of B. B will have a optional foreign key(may be null) referencing A. For performance reasons I also want table C to have the same foreign key reference to table A. The constraint on table C should be that C must reference its parent (B) and also have the same foreign key reference to A as its parent. Anyone have any thoughts on how to do this?

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  • dynamic SQL not working as expected

    - by christine33990
    create or replace procedure createtables Authid current_user as begin execute immediate 'create table newcustomer as select * from customer'; end; create or replace procedure e is begin createtables; select * from newcustomer; end; I got two procedures above. first one will create a new tables called newcustomer, second procedure will call the first procedure and query to the newcustomer table. when I try to compile this code, it says the table is not yet created, I don't really get it as I have called createtables procedure so I assume I have created the table. Any help will be appreciated. Thanks

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  • The right way to write "ID" in columns in SQL

    - by radbyx
    My first question in here. I like the site so much :) I've a SQL table called Product. In that table I want to make a column for the ID of the product, and I really like to now the right way of write ID because I make alot of ID columns in the long run. So is it: "ID" or "Id" ? And also a foreign key in another table, is that called ProductID or ProductId? Thx guys.

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  • TableView on Tab Bar Application ? Application is crashing.

    - by Andrei
    Steps to reproduce: 1. Create a Tab Bar Application called "TestApp" 2. Add new file, a UIViewController subclass with a XIB user interface called "Table" 3. Open up MainWindows.xib, click on the Second tab bar item and in Inspector change the NIB Name from "SecondView" to "Table". Save and close. 4. Open up Table.xib and drag a TableView on top of the view. Now link the dataSource and delegate outlets of the TableView to the Table.xib File's Owner. 5. Add the following code to Table.m: - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { NSLog(@"Returning num sections"); return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { NSLog(@"Returning num rows"); return 1; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"Trying to return cell"); static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease]; } cell.text = @"Hello"; NSLog(@"Returning cell"); return cell; } 6.Run the application and select the Second tab bar item. If I start with a View-based application, add a TableView to it, link the outlets to the File's owner and add that piece of code it all works just fine. What am I doing wrong ? Why is the application crashing ?

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  • Customers and suppliers database design issue

    - by hectorsq
    I am developing a web application in which I will have customers and suppliers. Initially I thought on using a Customers table and a Suppliers table. Then when I was thinking on bank transactions, I noticed that each transaction needs to refer to a customer or a supplier, so I thought on using a single table named Business in which I will save both customers and suppliers. If I use Customers and Suppliers tables when I want to list the bank transactions I will have to search in both tables to get the company name. If I use a Businesses table I will have to use a business type column, and have the union of possible fields for all businesses types. Any suggestions on the design?

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  • What is the difference between check and foreign key?

    - by GigaPr
    Hi, i am quite confused about the difference between a FOREIGN KEY and CHECK constraint. they appear to me to achieve the same result. I mean I could create a table and enforce a Foreign key on another table, but i could create a CHECK to ensure the value in in another table. What is the difference and when to use the one or the other? thanks

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  • Jquery .text() call returns null?

    - by Alex
    Hey all, I'm practicing Jquery and I've written this simple Jquery statement: var someText = $("table tr td").text(); Should this not return all text of td elements found within tr's that are found within tables? How do I fix this? Currently when I run this, it says that table tr td is null, but I have a table on the page I'm testing on. Thanks!

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  • Data from two tables without repeating data from the first?

    - by Aran
    I have two tables. Users table and Users Meta Table I am looking for a way to get all the information out of both tables with one query. But without repeating the information from Users table. This is all information relating to the users id number as well. So for example user_id = 1. Is there a way to query the database and collect all the information I from both tables without repeating the information from the first?

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  • Debugging (displaying) SQL command sent to the db by SQLAlchemy

    - by morpheous
    I have an ORM class called Person, which wraps around a person table: After setting up the connection to the db etc, I run the ff statement. people = session.query(Person).all() The person table does not contain any data (as yet), so when I print the variable people, I get an empty list. I renamed the table referred to in my ORM class People, to people_foo (which does not exist). I then run the script again. I was surprised that no exception was thrown when attempting to access a table that does not exist. I therefore have the following 2 questions: How may I setup SQLAlchemy so that it propagates db errors back to the script? How may I view (i.e. print) the SQL that is being sent to the db engine If it helps, I am using PostgreSQL as the db

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  • Extendable accessing of sqlite database on android platform

    - by mscriven
    Hi, I am fairly new to the android sdk and databases and have been searching for an answer to this quite some time. I am trying to build an app which has multiple tables within a database. e.g. one for weapons, armours etc. However, my DatabaseManager class which handles all of my table creating, DatabaseHelper inner class and populating of data is creating for an extremely large class requiring high maintenance. Every time I would like to add or remove a table column I need to change quite a few areas of code, - Every reference to the addition of a row in that table with data - The method that the above calls - The method returning all of the database rows - The code in the helper class creating the table - Any specific update methods My question is this: Surely there must be some better way of coding this system, maybe using a database isn't the best way to go, or am i just not used to such large classes having only learned java at university and my largest class consisting of a mere 400-600 lines of code. Thanks for any help!

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  • continuously fetch data from database using JAVA

    - by deathcaller
    Hi all, I've a scenario where my java program has to continuously communicate with the database table, example my java program has to get the data of my table when new rows are added to it at runtime. There should be continuous communication between my program and database. if the table has 10 rows initially and 2 rows are added by the user, it must detect this and return the rows. My program shouldn't use AJAX and timers. Please Help.

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  • SQL Select -> product -> comments -> user

    - by user1492716
    thanks for yout time helping on this ;) I'm new to SQL and wish to solve somethign in just one query and i dont know how to do it.- Basically I've a table of products, a table of users and a table of comments, linked by products.id - comments.pid and user.id - comments.uid , i wish to know what is the best practice to create just 1 query and get all products with child comments, including username.

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