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  • Good Hash Function for Strings

    - by Leif Andersen
    I'm trying to think up a good hash function for strings. And I was thinking it might be a good idea to sum up the unicode values for the first five characters in the string (assuming it has five, otherwise stop where it ends). Would that be a good idea, or is it a bad one? I am doing this in Java, but I wouldn't imagine that would make much of a difference.

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  • NHibernate Left Outer Join

    - by Matthew
    I'm looking to create a Left outer join Nhibernate query with multiple on statements akin to this: SELECT * FROM [Database].[dbo].[Posts] p LEFT JOIN [Database].[dbo].[PostInteractions] i ON p.PostId = i.PostID_TargetPost And i.UserID_ActingUser = 202 I've been fooling around with the critera and aliases, but I haven't had any luck figuring out how do to this. Any suggestions?

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  • SQL - How to join on similar (not exact) columns

    - by BlueRaja
    I have two tables which get updated at almost the exact same time - I need to join on the datetime column. I've tried this: SELECT * FROM A, B WHERE ABS(DATEDIFF(second, A.Date_Time, B.Date_Time) = ( SELECT MIN(ABS(DATEDIFF(second, A.Date_Time, B2.Date_Time))) FROM B AS B2 ) But it tells me: Multiple columns are specified in an aggregated expression containing an outer reference. If an expression being aggregated contains an outer reference, then that outer reference must be the only column referenced in the expression. How can I join these tables?

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  • Use hash or case-statement [Ruby]

    - by user94154
    Generally which is better to use?: case n when 'foo' result = 'bar' when 'peanut butter' result = 'jelly' when 'stack' result = 'overflow' return result or map = {'foo' => 'bar', 'peanut butter' => 'jelly', 'stack' => 'overflow'} return map[n] More specifically, when should I use case-statements and when should I simply use a hash?

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  • SQL join produces one result only

    - by Rami
    Can anyone please tell me why this result is generation only one results? taking in mind that everything is set right and the three tables are populated correctly, i took out the group_concat and it worked but of course with a php undefined index error! SELECT `songs`.`song_name`, `songs`.`add_date`, `songs`.`song_id`, `songs`.`song_picture`, group_concat(DISTINCT artists.artist_name) as artist_name FROM (`songs`) JOIN `mtm_songs_artists` ON `songs`.`song_id` = `mtm_songs_artists`.`song_id` JOIN `artists` ON `artists`.`artist_id` = `mtm_songs_artists`.`artist_id` ORDER BY `songs`.`song_id` DESC LIMIT 10 so i'm guessing it's something related to group_concat. best regards, Rami

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  • Using CASE Statements in LEFT OUTER JOIN in SQL

    - by s khan
    I've got a scenario where I want to switch on two different tables in an outer join. It goes something like this:- select mytable.id, yourtable.id from mytable left outer join (case when mytable.id = 2 then table2 yourtable on table1.id = table2.id else table3 yourtable on table1.id = table3.id end) ...but it doesn't work. Any suggestions?

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  • web application , join event on facebook using php api

    - by Mohammed Al-shareif
    enter code herei created my events on facebook throw php api (form my website) ...every thing its fine with me and the events appear 100% on FB calendar , i got the FB event id and save to my db , enter code here my users can join the same event on my website i need them to join the same event on facebook also i have the facebook event id , and user accept my permission to access his/here calendar please anybody help!!!

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  • join two table for insert data in database in android

    - by shadi
    I have two table(t1,t2) in android, t1 has a primary key that it is foreign key for t2,i want to insert data to this tables,is it necessary to join these two table?if yes, what is code for join these table? i insert data in one of them like this: public long insertQuote(String Quote,int Count1 ) { ContentValues initialValues = new ContentValues(); initialValues.put(GoodName, Quote); initialValues.put(CartID, Count1); return db.insert(DATABASE_TABLE, null, initialValues); }

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  • linq to entites left outer join

    - by parminder
    I am struggling linq to entities left outer join. I have two entities (tables): Listings { ListingID, MakeID (nullable) } Makes { MakeID, Description } I want to write something like this in LINQ: select listings.listingID ,listings.makeid , IsNull(makes.Description, 'NA') from listings left outer join makes on listings.makeid = makes.makeid

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  • Data retrieval and Join operations with cluster db server

    - by Goerge
    If any database spreads across multiple servers (ex. Microsoft Sql Server), how can we do join or filter operations. In my scenario, if suppose: A single table spreads across multiple servers how can we filter rows based on user input? If master table is there on one db server and transaction table is at another db server, how can we do join operations? Please let me know how can we achieve this and where can I get more details about this?

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  • Appending a prefix when using join in Perl

    - by syker
    I have an array of strings that I would like to use the join function on. However, I would like to prefix each string with the same string. Can I do this in one line as opposed to iterating through the array first and changing each value before using join?

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  • entity framework join

    - by Luca Romagnoli
    Hi, i have 2 table (user, user_profile) without a explicit relationship in the sql db. and i can't add it to the db. so, i can't do this: db.user.include("user_profile") the attribute in for the join is user_id is possible do anything like this? db.user.join("user_profile On user.id = user_profile.user_id") How can i do that? thanks

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  • LINQ 2 SQL:Left outer join for my SQL statement

    - by Shyju
    Can any one tell me the LINQ 2 SQL version (in vb.net) of the below Left outer join query.I am trying to get all Employees with name "Shyju" and their address line 1 if it exist in the address table SELECT E.EMPLOYEE_NAME, E.AGE,A.ADRESS_LINE1 FROM EMPLOYEE_MASTER E LEFT OUTER JOIN ADDRESS_MASTER A ON E.ID=A.EMPLOYEE_ID WHERE E.EMPLOYEE_NAME='Shyju' Thanks in advance

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  • hash password in mssql (asp.net)

    - by ile
    Is this how hashed password stored in mssql should look like? This is function I use to hash password (I found it in some tutorial) public string EncryptPassword(string password) { //we use codepage 1252 because that is what sql server uses byte[] pwdBytes = Encoding.GetEncoding(1252).GetBytes(password); byte[] hashBytes = System.Security.Cryptography.MD5.Create().ComputeHash(pwdBytes); return Encoding.GetEncoding(1252).GetString(hashBytes); } Thanks, Ile

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  • Python: Split, strip, and join in one line

    - by PandemoniumSyndicate
    I'm curious if their is some python magic I may not know to accomplish a bit of frivolity given the line: csvData.append(','.join([line.split(":").strip() for x in L])) I'm attempting to split a line on :, trim whitespace around it, and join on , problem is, since the array is returned from line.split(":"), the for x in L #<== L doesn't exist! causes issues since I have no name for the array returned by line.split(":") So I'm curious if there is a sexy piece of syntax I could use to accomplish this in one shot? Cheers!

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  • Perl, convert hash to array

    - by Mike
    If I have a hash in Perl that contains complete and sequential integer mappings (ie, all keys from from 0 to n are mapped to something), is there a means of converting this to an Array? I know I could iterate over the key/value pairs and place them into a new array, but something tells me there should be a built-in means of doing this.

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  • MySQL: Use CASE/ELSE value as join parameter

    - by DRJ
    I'm trying to join the NAME and PHOTO from USERS table to the TRANSACTIONS table based on who is the payer or payee. It keeps telling me can't find the table this -- What am I doing wrong? SELECT name,photo,amount,comment, ( CASE payer_id WHEN 72823 THEN payee_id ELSE payer_id END ) AS this FROM transactions RIGHT JOIN users ON (users.id=this) WHERE payee_id=72823 OR payer_id=72823

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  • Join two results in Powershell

    - by Hinek
    I've got two CMDlets that return lists of objects. One returns objects of the type SPSolution, which contains the property Id, the other returns objects of the type SPFeature with a property SolutionId. Now I want to join/merge this data something like this: $f = Get-Feature $s = Get-Solution $result = <JOIN> $f $s <ON> $f.SolutionId = $s.Id <SELECT> FeatureName = $f.DisplayName, SolutionName = $s.Name

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  • Complex multiple join query across 3 tables

    - by Keir Simmons
    I have 3 tables: shops, PRIMARY KEY cid,zbid shop_items, PRIMARY KEY id shop_inventory, PRIMARY KEY id shops a is related to shop_items b by the following: a.cid=b.cid AND a.zbid=b.szbid shops is not directly related to shop_inventory shop_items b is related to shop_inventory c by the following: b.cid=c.cid AND b.id=c.iid Now, I would like to run a query which returns a.* (all columns from shops). That would be: SELECT a.* FROM shops a WHERE a.cid=1 AND a.zbid!=0 Note that the WHERE clause is necessary. Next, I want to return the number of items in each shop: SELECT a.*, COUNT(b.id) items FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid WHERE a.cid=1 GROUP BY b.szbid,b.cid As you can see, I have added a GROUP BY clause for this to work. Next, I want to return the average price of each item in the shop. This isn't too hard: SELECT a.*, COUNT(b.id) items, AVG(COALESCE(b.price,0)) average_price FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid WHERE a.cid=1 GROUP BY b.szbid,b.cid My next criteria is where it gets complicated. I also want to return the unique buyers for each shop. This can be done by querying shop_inventory c, getting the COUNT(DISTINCT c.zbid). Now remember how these tables are related; this should only be done for the rows in c which relate to an item in b which is owned by the respective shop, a. I tried doing the following: SELECT a.*, COUNT(b.id) items, AVG(COALESCE(b.price,0)) average_price, COUNT(DISTINCT c.zbid) FROM shops a LEFT JOIN shop_items b ON b.cid=a.cid AND b.szbid=a.zbid LEFT JOIN shop_inventory c ON c.cid=b.cid AND c.iid=b.id WHERE a.cid=1 GROUP BY b.szbid,b.cid However, this did not work as it messed up the items value. What is the proper way to achieve this result? I also want to be able to return the total number of purchases made in each shop. This would be done by looking at shop_inventory c and adding up the c.quantity value for each shop. How would I add that in as well?

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  • LINQ Joins - Performance

    - by Meiscooldude
    I am curious on how exactly LINQ (not LINQ to SQL) is performing is joins behind the scenes in relation to how Sql Server performs joins. Sql Server before executing a query, generates an Execution Plan. The Execution Plan is basically an Expression Tree on what it believes is the best way to execute the query. Each node provides information on whether to do a Sort, Scan, Select, Join, ect. On a 'Join' node in our execution plan, we can see three possible algorithms; Hash Join, Merge Join, and Nested Loops Join. Sql Server will choose which algorithm to for each Join operation based on expected number of rows in Inner and Outer tables, what type of join we are doing (some algorithms don't support all types of joins), whether we need data ordered, and probably many other factors. Join Algorithms: Nested Loop Join: Best for small inputs, can be optimized with ordered inner table. Merge Join: Best for medium to large inputs sorted inputs, or an output that needs to be ordered. Hash Join: Best for medium to large inputs, can be parallelized to scale linearly. LINQ Query: DataTable firstTable, secondTable; ... var rows = from firstRow in firstTable.AsEnumerable () join secondRow in secondTable.AsEnumerable () on firstRow.Field<object> (randomObject.Property) equals secondRow.Field<object> (randomObject.Property) select new {firstRow, secondRow}; SQL Query: SELECT * FROM firstTable fT INNER JOIN secondTable sT ON fT.Property = sT.Property Sql Server might use a Nested Loop Join if it knows there are a small number of rows from each table, a merge join if it knows one of the tables has an index, and Hash join if it knows there are a lot of rows on either table and neither has an index. Does Linq choose its algorithm for joins? or does it always use one?

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  • showing null rows using join

    - by Pradyut Bhattacharya
    Hi, In mysql i m selecting from a table shouts having a foreign key to another table named "roleuser" with the matching column as user_id Now the user_id column in the shouts table for some rows is null (not actually null but with no inserts in mysql) How to show all the rows of the shouts table either with user_id null or not I m executing the sql statement SELECT s.*, r.firstname, r.lastname FROM shouts s left join roleuser r where r.user_id = s.user_id limit 50; which does not executes and shows You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'where r.user_id = s.user_id limit 50' at line 2 but using inner join the sql executes which shows rows which only have user_id values in the shouts table. the nulls are not shown. SELECT s.*, r.firstname, r.lastname FROM shouts s inner join roleuser r where r.user_id = s.user_id limit 50; How can i show all the rows from the shouts table and null values in the firstname and lastname columns where the user_id is null in the shouts table. If not at all possible with sql may be using stored procedures... Thanks Pradyut

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  • Problem with duplicates in a SQL Join

    - by Chris Ballance
    I have the following result set from a join of three tables, an articles table, a products table, an articles to products mapping table. I would like to have the results with duplicates removed similar to a select distinct on content id. Current result set: [ContendId] [Title] [productId] 1 article one 2 1 article one 3 1 article one 9 4 article four 1 4 article four 10 4 article four 14 5 article five 1 6 article six 8 6 article six 10 6 article six 11 6 article six 13 7 article seven 14 Desired result set: [ContendId] [Title] [productId] 1 article one * 4 article four * 5 article five * 6 article six * 7 article seven * Here is condensed example of the relevant SQL: IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'tempdb.dbo.products') AND type = (N'U')) drop table tempdb.dbo.products go CREATE TABLE tempdb.dbo.products ( productid int, productname varchar(255) ) go IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articles') AND type = (N'U')) drop table tempdb.dbo.articles go create table tempdb.dbo.articles ( contentid int, title varchar(255) ) IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articles') AND type = (N'U')) drop table tempdb.dbo.articles go create table tempdb.dbo.articles ( contentid int, title varchar(255) ) IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articleproducts') AND type = (N'U')) drop table tempdb.dbo.articleproducts go create table tempdb.dbo.articleproducts ( contentid int, productid int ) insert into tempdb.dbo.products values (1,'product one'), (2,'product two'), (3,'product three'), (4,'product four'), (5,'product five'), (6,'product six'), (7,'product seven'), (8,'product eigth'), (9,'product nine'), (10,'product ten'), (11,'product eleven'), (12,'product twelve'), (13,'product thirteen'), (14,'product fourteen') insert into tempdb.dbo.articles VALUES (1,'article one'), (2, 'article two'), (3, 'article three'), (4, 'article four'), (5, 'article five'), (6, 'article six'), (7, 'article seven'), (8, 'article eight'), (9, 'article nine'), (10, 'article ten') INSERT INTO tempdb.dbo.articleproducts VALUES (1,2), (1,3), (1,9), (4,1), (4,10), (4,14), (5,1), (6,8), (6,10), (6,11), (6,13), (7,14) GO select DISTINCT(a.contentid), a.title, p.productid from articles a JOIN articleproducts ap ON a.contentid = ap.contentid JOIN products p ON a.contentid = ap.contentid AND p.productid = ap.productid ORDER BY a.contentid

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