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  • MySQL create view from concat value

    - by cnotethegr8
    Lets say I have a table as follows, +----+-------------+ | id | value | +----+-------------+ | 1 | aa,bb,cc,dd | | 2 | ee,ff,gg,hh | +----+-------------+ I want to be able to search this table to see if id = 1 AND value = 'cc'. Im assuming a good way of doing this is to grab the id = 1 row and split its values into separate rows in a new view. Something like, +-----+ | val | +-----+ | aa | | bb | | cc | | dd | +-----+ I would like to do all of this in MySQL. How can i do this, and is there possibly a better way to do it?

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  • filter duplicates in SQL join

    - by Will
    When using a SQL join, is it possible to keep only rows that have a single row for the left table? For example: select * from A, B where A.id = B.a_id; a1 b1 a2 b1 a2 b2 In this case, I want to remove all except the first row, where a single row from A matched exactly 1 row from B. I'm using MySQL.

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  • Is this postgres function cost efficient or still have to clean

    - by kiranking
    There are two tables in postgres db. english_all and english_glob First table contains words like international,confidential,booting,cooler ...etc I have written the function to get the words from english_all then perform for loop for each word to get word list which are not inserted in anglish_glob table. Word list is like I In Int Inte Inter .. b bo boo boot .. c co coo cool etc.. for some reason zwnj(zero-width non-joiner) is added during insertion to english_all table. But in function I am removing that character with regexp_replace. Postgres function for_loop_test is taking two parameter min and max based on that I am selecting words from english_all table. function code is like DECLARE inMinLength ALIAS FOR $1; inMaxLength ALIAS FOR $2; mviews RECORD; outenglishListRow english_word_list;--custom data type eng_id,english_text BEGIN FOR mviews IN SELECT id,english_all_text FROM english_all where wlength between inMinLength and inMaxLength ORDER BY english_all_text limit 30 LOOP FOR i IN 1..char_length(regexp_replace(mviews.english_all_text,'(?)$','')) LOOP FOR outenglishListRow IN SELECT distinct on (regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','')) mviews.id, regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') where regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') not in(select english_glob.english_text from english_glob where i=english_glob.wlength) order by regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') LOOP RETURN NEXT outenglishListRow; END LOOP; END LOOP; END LOOP; END; Once I get the word list I will insert that into another table english_glob. My question is is there any thing I can add to or remove from function to make it more efficient. edit Let assume english_all table have words like footer,settle,question,overflow,database,kingdom If inMinLength = 5 and inmaxLength=7 then in the outer loop footer,settle,kingdom will be selected. For above 3 words inner two loop will apply to get words like f,fo,foo,foot,foote,footer,s,se,set,sett,settl .... etc. In the final process words which are bold will be entered into english_glob with another parameter like 1 to denote it is a proper word and stored in the another filed of english_glob table. Remaining word will be stored with another parameter 0 because in the next call words which are saved in database should not be fetched again. edit2: This is a complete code CREATE TABLE english_all ( id serial NOT NULL, english_all_text text NOT NULL, wlength integer NOT NULL, CONSTRAINT english_all PRIMARY KEY (id), CONSTRAINT english_all_kan_text_uq_id UNIQUE (english_all_text) ) CREATE TABLE english_glob ( id serial NOT NULL, english_text text NOT NULL, is_prop integer default 1, CONSTRAINT english_glob PRIMARY KEY (id), CONSTRAINT english_glob_kan_text_uq_id UNIQUE (english_text) ) insert into english_all(english_text) values ('ant'),('forget'),('forgive'); on function call with parameter 3 and 6 fallowing rows should fetched a an ant f fo for forg forge forget next is insert to another table based on above row insert into english_glob(english_text,is_prop) values ('a',1),('an',1), ('ant',1),('f',0), ('fo',0),('for',1), ('forg',0),('forge',1), ('forget',1), on function call next time with parameter 3 and 7 fallowing rows should fetched.(because f,fo,for,forg are all entered in english_glob table) forgi forgiv forgive

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  • Whats better query with long where in condition or many small queries?

    - by DCrystal
    Maybe it's a little dumb, but i'm just not sure what is better. If i have to check about 30k rows in db for existanse, what i'd do? #1 - one query select id from table1 where name in (smth1,smth2...{till 30k}) #2 - many queries select id from table1 where name=smth1 Though, perfomance is not the goal, i don't want to go down with mysql either ;) Maybe, any other solutions will be more suitable... Thanks.

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  • mysql query help please

    - by moustafa
    i have forum_topics table and have topics_posts table now i want to select from forum_topics where have no posts from topics_posts can any one give me the one syntax like this selct from * forum_topics where have no rows in topics_posts table

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  • Subband decomposition using Daubechies filter

    - by misha
    I have the following two 8-tap filters: h0 ['-0.010597', '0.032883', '0.030841', '-0.187035', '-0.027984', '0.630881', '0.714847', '0.230378'] h1 ['-0.230378', '0.714847', '-0.630881', '-0.027984', '0.187035', '0.030841', '-0.032883', '-0.010597'] Here they are on a graph: I'm using it to obtain the approximation (lower subband of an image). This is a(m,n) in the following diagram: I got the coefficients and diagram from the book Digital Image Processing, 3rd Edition, so I trust that they are correct. The star symbol denotes one dimensional convolution (either over rows or over columns). The down arrow denotes downsampling in one dimension (either over rows, or columns). My problem is that the filter coefficients for h0 and h1 sum to greater than 1 (approximately 1.4 or sqrt(2) to be exact). Naturally, if I convolve any image with the filter, the image will get brighter. Indeed, here's what I get (expected result on right): Can somebody suggest what the problem is here? Why should it work if the convolution filter coefficients sum to greater than 1? I have the source code, but it's quite long so I'm hoping to avoid posting it here. If it's absolutely necessary, I'll put it up later. EDIT What I'm doing is: Decompose into subbands Filter one of the subbands Recompose subbands into original image Note that the point isn't just to have a displayable subband-decomposed image -- I have to be able to perfectly reconstruct the original image from the subbands as well. So if I scale the filtered image in order to compensate for my decomposition filter making the image brighter, this is what I will have to do: Decompose into subbands Apply intensity scaling Filter one of the subbands Apply inverse intensity scaling Recompose subbands into original image Step 2 performs the scaling. This is what @Benjamin is suggesting. The problem is that then step 4 becomes necessary, or the original image will not be properly reconstructed. This longer method will work. However, the textbook explicitly says that no scaling is performed on the approximation subband. Of course, it's possible that the textbook is wrong. However, what's more possible is I'm misunderstanding something about the way this all works -- this is why I'm asking this question.

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  • Mass update of data in sql from int to varchar

    - by Christopher Kelly
    we have a large table (5608782 rows and growing) that has 3 columns Zip1,Zip2, distance all columns are currently int, we would like to convert this table to use varchars for international usage but need to do a mass import into the new table convert zip < 5 digits to 0 padded varchars 123 becomes 00123 etc. is there a way to do this short of looping over each row and doing the translation programmaticly?

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  • Memory Allocation increases in didSelectRowAtIndexPath

    - by mongeta
    Hello, I'm testing my App and in a very simple view, each time a tap on a UITableView row, my allocation overall bytes get higher and higher and never go downs. I don't have any special code there, so I created a new project from scratch with a very simple view, force one section and just three rows. In the didSelectRowAtIndexPath code do nothing, and fire it with instruments and memory allocation and, the memory goes up with every cell selection ... Is this normal behaviour ? thanks, regards, m.

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  • What is the equivalent of REGEXP_SUBSTR in mysql?

    - by KandadaBoggu
    I want to extract a word from a string column of a table. description =========================== abc order_id: 2 xxxx yyy aa mmm order_id: 3 nn kk yw Expected result set order_id =========================== 2 3 Table will at most have 100 rows, text length is ~256 char and column always has one order_id present. So performance is not an issue. In Oracle, I can use REGEXP_SUBSTR for this problem. How would I solve this in MySQL?

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  • Datable.Select sort expression

    - by xyz
    Hi, I have datatable with column name tag and 100 rows of data.I need to filter this table with tag starting with "UNKNOWN". What should my sortexpression for datatable.select be ? I'm trying the following. Datarow[] abc = null; abc = dtTagList.Select(string.format("tag='{0}'","UNKNOWN")) How can I achieve tag startswith 'UNKNOWN' in the above code ?

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  • Two UITableView in one UIViewController problem

    - by georgij
    I considered to use two UITableView in one UIViewController which is also do data source for them but encountered the problem that while both tables visit numberOfRowsInSection only one visit cellForRowAtIndexPath at the start and both tables contain empty rows. Do someone know why this happens?

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  • Multi-Column Primary Key in MySQL 5

    - by Kaji
    I'm trying to learn how to use keys and to break the habit of necessarily having SERIAL type IDs for all rows in all my tables. At the same time, I'm also doing many-to-many relationships, and so requiring unique values on either column of the tables that coordinate the relationships would hamper that. How can I define a primary key on a table such that any given value can be repeated in any column, so long as the combination of values across all columns is never repeated exactly?

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  • what is the event to handle row scrolling in EXTJS Gridpanel?

    - by user1480705
    I am displaying data in a GridPanel. My requirement is to hide some menu items based on the row selections. I have this perfectly working when a user clicks or rightclicks - i am handling the event for rowclick and rowcontextmenu respecitvely. But i am facing issue to locate the event - If the user first clicks on the row and them use up and down arrows to move on to other rows. Thanks in Advance

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  • Linq to SQL - Returning two values with one query

    - by Sir Psycho
    Hi, Is it possible to return a single value and an enumerable collection using LINQ to SQL? The problem is, I'm trying to do paging across a large recordset. I only want to return 10 rows at a time so I'm using .Skip(20).Take(10) approach. However I need to know the total number of records so I can show an appropriate page x of y. Trying to avoid two separate queries. Thanks

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  • Mysql select - improve performances

    - by realshadow
    Hey, I am working on an e-shop which sells products only via loans. I display 10 products per page in any category, each product has 3 different price tags - 3 different loan types. Everything went pretty well during testing time, query execution time was perfect, but today when transfered the changes to the production server, the site "collapsed" in about 2 minutes. The query that is used to select loan types sometimes hangs for ~10 seconds and it happens frequently and thus it cant keep up and its hella slow. The table that is used to store the data has approximately 2 milion records and each select looks like this: SELECT * FROM products_loans WHERE KOD IN("X17/Q30-10", "X17/12", "X17/5-24") AND 369.27 BETWEEN CENA_OD AND CENA_DO; 3 loan types and the price that needs to be in range between CENA_OD and CENA_DO, thus 3 rows are returned. But since I need to display 10 products per page, I need to run it trough a modified select using OR, since I didnt find any other solution to this. I have asked about it here, but got no answer. As mentioned in the referencing post, this has to be done separately since there is no column that could be used in a join (except of course price and code, but that ended very, very badly). Here is the show create table, kod and CENA_OD/CENA_DO very indexed via INDEX. CREATE TABLE `products_loans` ( `KOEF_ID` bigint(20) NOT NULL, `KOD` varchar(30) NOT NULL, `AKONTACIA` int(11) NOT NULL, `POCET_SPLATOK` int(11) NOT NULL, `koeficient` decimal(10,2) NOT NULL default '0.00', `CENA_OD` decimal(10,2) default NULL, `CENA_DO` decimal(10,2) default NULL, `PREDAJNA_CENA` decimal(10,2) default NULL, `AKONTACIA_SUMA` decimal(10,2) default NULL, `TYP_VYHODY` varchar(4) default NULL, `stage` smallint(6) NOT NULL default '1', PRIMARY KEY (`KOEF_ID`), KEY `CENA_OD` (`CENA_OD`), KEY `CENA_DO` (`CENA_DO`), KEY `KOD` (`KOD`), KEY `stage` (`stage`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 And also selecting all loan types and later filtering them trough php doesnt work good, since each type has over 50k records and the select takes too much time as well... Any ides about improving the speed are appreciated. Edit: Here is the explain +----+-------------+----------------+-------+---------------------+------+---------+------+--------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------------+-------+---------------------+------+---------+------+--------+-------------+ | 1 | SIMPLE | products_loans | range | CENA_OD,CENA_DO,KOD | KOD | 92 | NULL | 190158 | Using where | +----+-------------+----------------+-------+---------------------+------+---------+------+--------+-------------+ I have tried the combined index and it improved the performance on the test server from 0.44 sec to 0.06 sec, I cant access the production server from home though, so I will have to try it tomorrow.

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  • SQL Server - Test the result of a stored procedure

    - by Melursus
    In SQL Server, it is possible to test the result of a stored procedure to know if the result return rows or nothing ? Example : EXEC _sp_MySp 1, 2, 3 IF @@ROWCOUNT = 0 BEGIN PRINT('Empty') END ELSE BEGIN PRINT(@@ROWCOUNT) END But @@ROWCOUNT always return 0 so maybe is there another way of doing this ?

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  • Keeping DB Table sorted using multi-field formula (Microsoft SQL Server)

    - by user298167
    I have a JOB table, with two interesting columns: Creation Date Importance (high - 3, medium 2, low - 1). A JOB record's priority calculated like this: Priority = Importance * (time passed since creation) The problem is, every time I would like to pick 200 jobs with highest priority, and I don't want to resort the table. Is there a way to keep rows sorted? I was also thinking about having three tables one for High, Medium and Low and then sort those by Creation Date.

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  • Paginating data, has to be a better way

    - by John Tyler
    I've read like 10 or so "tutorials", and they all involve the same thing: Pull a count of the data set Pull the relevant data set (LIMIT, OFFSET) IE: SELECT COUNT(*) FROM table WHERE something = ? SELECT * FROM table WHERE something =? LIMIT ? offset ?` Two very similar queries, no? There has to be a better way to do this, my dataset is 600,000+ rows and already sluggish (results are determined by over 30 where clauses, and vary from user to user, but are properly indexed of course).

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  • ActiveRecord finding from inside a serialized field

    - by JP
    While working with ActiveRecord I have a table which stores a serialized array of participant usernames for each row. Is there an easy way to search for all rows who contain a specific user? I realise I could just make a new linked table for the participants, but I feel like that would increase my overhead unnecessarily -- what do you think?

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