Search Results

Search found 27519 results on 1101 pages for 'sql learner'.

Page 673/1101 | < Previous Page | 669 670 671 672 673 674 675 676 677 678 679 680  | Next Page >

  • One on One table relation - is it harmful to keep relation in both tables?

    - by EBAGHAKI
    I have 2 tables that their rows have one on one relation.. For you to understand the situation, suppose there is one table with user informations and there is another table that contains a very specific informations and each user can only link to one these specific kind of informations ( suppose second table as characters ) And that character can only assign to the user who grabs it, Is it against the rules of designing clean databases to hold the relation key in both tables? User Table: user_id, name, age, character_id Character Table: character_id, shape, user_id I have to do it for performance, how do you think about it?

    Read the article

  • MYSQL: COUNT with GROUP BY, LEFT JOIN and WHERE clause doesn't return zero values

    - by Paul Norman
    Hi guys, thanks in advance for any help on this topic! I'm sure this has a very simply answer, but I can't seem to find it (not sure what to search on!). A standard count / group by query may look like this: SELECT COUNT(`t2`.`name`) FROM `table_1` `t1` LEFT JOIN `table_2` `t2` ON `t1`.`key_id` = `t2`.`key_id` GROUP BY `t1`.`any_col` and this works as expected, returning 0 if no rows are found. So does: SELECT COUNT(`t2`.`name`) FROM `table_1` `t1` LEFT JOIN `table_2` `t2` ON `t1`.`key_id` = `t2`.`key_id` WHERE `t1`.`another_column` = 123 However: SELECT COUNT(`t2`.`name`) FROM `table_1` `t1` LEFT JOIN `table_2` `t2` ON `t1`.`key_id` = `t2`.`key_id` WHERE `t1`.`another_column` = 123 GROUP BY `t1`.`any_col` only works if there is at least one row in table_1 and fails miserably returning an empty result set if there are zero rows. I would really like this to return 0! Anyone enlighten me on this? Beer can be provided in exchange if you are in London ;-)

    Read the article

  • Access database query locks ability to edit table?

    - by Sattvic
    I created a query in Microsoft Access like the one below: SELECT Deliverables.ID, Deliverables.Title, Deliverables.Summary, Deliverables.Header_Code, Deliverables.Header_Code.Value, Deliverables.Sort_order, Deliverables.Pillar, Deliverables.Pillar.Value, Deliverables.Misc_ID FROM Deliverables WHERE (((Deliverables.Pillar.Value)="Link Building")); But my problem is that this query locks my fields and I cannot make changes to the table using the query view. Any suggestions? I am using Microsoft Access 2007

    Read the article

  • Does the order of the columns in a SELECT statement make a difference?

    - by Frank Computer
    This question was inspired by a previous question posted on SO, "Does the order of the WHERE clause make a differnece?". Would it improve a SELECT statement's performance if the the columns used in the WHERE section are placed at the begining of the SELECT statement? example: SELECT customer.id, transaction.id, transaction.efective_date, transaction.a, [...] FROM customer, transaction WHERE customer.id = transaction.id; I do know that limiting the list of columns to only the needed ones in a SELECT statement improves performance as opposed to using SELECT * because the current list is smaller.

    Read the article

  • Database design

    - by Hadad
    Hello, I've a system, that have two types of users (Companies and individuals).all types have a shared set of properties but they differ in another. What is the best design merge all in one table that allows null for unmatched properties, or separate them in two tables related to a basic table with a one to one relationship. Thanks.

    Read the article

  • Query returning an ascending group number

    - by Dougman
    I have a query like below that has groups (COL1) and that group's values (COL2). select col1, col2 from (select 'A' col1, 1 col2 from dual union all select 'A' col1, 2 col2 from dual union all select 'B' col1, 1 col2 from dual union all select 'B' col1, 2 col2 from dual union all select 'C' col1, 1 col2 from dual union all select 'C' col1, 2 col2 from dual ) order by col1, col2; The output of this query looks like: COL1 COL2 ---- ---- A 1 A 2 B 1 B 2 C 1 C 2 What I need is a query that will return an ordered number increasing for each different group (COL1). It seems like there would be a simple way to accomplish this (maybe with analytics) but for some reason it is escaping me. GRPNUM COL1 COL2 ------ ---- ---- 1 A 1 1 A 2 2 B 1 2 B 2 3 C 1 3 C 2 I am running Oracle 10gR2.

    Read the article

  • limiting mysql results by range of a specific key INCLUDING DUPLICATES

    - by aVC
    I have a query SELECT p.*, m.*, (SELECT COUNT(*) FROM newPhotoonAlert n WHERE n.userIDfor='$id' AND n.threadID=p.threadID and n.seen='0') AS unReadCount FROM posts p JOIN myMembers m ON m.id = p.user_id LEFT JOIN following f ON (p.user_id = f.user_id AND f.follower_id='$id' AND f.request='0' AND f.status='1') JOIN myMembers searcher ON searcher.id = '$id' WHERE ((f.follower_id = searcher.id) OR m.id='$id') AND p.flagged <'5' ORDER BY p.threadID DESC,p.positionID It brings result as expected but I want to add Another CLAUSE to limit the results. Say a sample (minimal shown) set of data looks like this with the above query. threadID postID positionID url 564 1254 2 a.com 564 1245 1 a1.com 541 1215 3 b1.com 541 1212 2 b2.com 541 1210 1 b3.com 523 745 1 c1.com 435 689 2 d2.com 435 688 1 a4.com 256 345 1 s3.com 164 316 1 f1.com . . I want to get ROWS corresponding to 2 DISTINCT threadIDs starting from MAX, but I want to include duplicates as well. Something like AND p.threadID IN (Select just Two of all threadIDs currently selected, but include duplicate rows) So my result should be threadID postID positionID url 564 1254 2 a.com 564 1245 1 a1.com 541 1215 3 b1.com 541 1212 2 b2.com 541 1210 1 b3.com

    Read the article

  • Insert into select and update in single query

    - by Ossi
    I have 4 tables: tempTBL, linksTBL and categoryTBL, extra on my tempTBL I have: ID, name, url, cat, isinserted columns on my linksTBL I have: ID, name, alias columns on my categoryTBL I have: cl_id, link_id,cat_id on my extraTBL I have: id, link_id, value How do I do a single query to select from tempTBL all items where isinsrted = 0 then insert them to linksTBL and for each record inserted, pickup ID (which is primary) and then insert that ID to categoryTBL with cat_id = 88. after that insert extraTBL ID for link_id and url for value. I know this is so confusing, put I'll post this anyhow... This is what I have so far: INSERT IGNORE INTO linksTBL (link_id,link_name,alias) VALUES(NULL,'tex2','hello'); # generate ID by inserting NULL INSERT INTO categoryTBL (link_id,cat_id) VALUES(LAST_INSERT_ID(),'88'); # use ID in second table I would like to add here somewhere that it only selects items where isinserted = 0 and iserts those records, and onse inserted, will change isinserted to 1, so when next time it runs, it will not add them again.

    Read the article

  • Oracle - truncating a global temporary table

    - by superdario
    I am processing large amounts of data in iterations, each and iteration processes around 10-50 000 records. Because of such large number of records, I am inserting them into a global temporary table first, and then process it. Usually, each iteration takes 5-10 seconds. Would it be wise to truncate the global temporary table after each iteration so that each iteration can start off with an empty table? There are around 5000 iterations.

    Read the article

  • left join without duplicate values using MIN()

    - by Clipper87
    I have a table_1: id custno 1 1 2 2 3 3 and a table_2: id custno qty descr 1 1 10 a 2 1 7 b 3 2 4 c 4 3 7 d 5 1 5 e 6 1 5 f When I run this query to show the minimum order quantities from every customer: SELECT DISTINCT table_1.custno,table_2.qty,table_2.descr FROM table_1 LEFT OUTER JOIN table_2 ON table_1.custno = table_2.custno AND qty = (SELECT MIN(qty) FROM table_2 WHERE table_2.custno = table_1.custno ) Then I get this result: custno qty descr 1 5 e 1 5 f 2 4 c 3 7 d Customer 1 appears twice each time with the same minimum qty (& a different description) but I only want to see customer 1 appear once. I don't care if that is the record with 'e' as a description or 'f' as a description. How could I do this ? Thx!

    Read the article

  • is Payment table needed when you have an invoice table like this?

    - by EBAGHAKI
    this is my invoice table: Invoice Table: invoice_id creation_date due_date payment_date status enum('not paid','paid','expired') user_id total_price I wonder if it's Useful to have a payment table in order to record user payments for invoices. payment table can be like this: payment_id payment_date invoice_id price_paid status enum('successful', 'not successful')

    Read the article

  • Performance optimization for mssql: decrease stored procedures execution time or unload the server?

    - by tim
    Hello everybody! We have a web service which provides search over hotels. There is a problem with performance: a single request to the service takes around 5000 ms. Almost all of the time is spent in database by executing storing procedures. During the request our server (mssql2008) consumes ~90% of the processor time. When 2 requests are made in parallel the average time grows and is around 7000 ms. When number of request is increasing, the average time of response is increasing as well. We have 20-30 requests per minute. Which kind of optimization is the best in this case having in mind that the goal is to provide stable response time for the service: 1) Try to decrease the stored procedures execution time 2) Try to find the way how to unload the server It is interesting to hear from people who deal with booking sites. Thanks!

    Read the article

  • Redundancy in doing sum()

    - by Abhi
    table1 - id, time_stamp, value This table consists of 10 id's. Each id would be having a value for each hour in a day. So for 1 day, there would be 240 records in this table. table2 - id Table2 consists of a dynamically changing subset of id's present in table1. At a particular instance, the intention is to get sum(value) from table1, considering id's only in table2, grouping by each hour in that day, giving the summarized values a rank and repeating this each day. the query is at this stage: select time_stamp, sum(value), rank() over (partition by trunc(time_stamp) order by sum(value) desc) rn from table1 where exists (select t2.id from table2 t2 where id=t2.id) and time_stamp >= to_date('05/04/2010 00','dd/mm/yyyy hh24') and time_stamp <= to_date('25/04/2010 23','dd/mm/yyyy hh24') group by time_stamp order by time_stamp asc If the query is correct, can this be made more efficient, considering that, table1 will actually consist of thousand's of id's instead of 10 ? EDIT: I am using sum(value) 2 times in the query, which I am not able to get a workaround such that the sum() is done only once. Pls help on this

    Read the article

  • Combine First, Middle Initial, Last name and Suffix in T-SQL (No extra spaces)

    - by Paul
    I'm trying not to reinvent the wheel here...I have these four fields [tbl_Contacts].[FirstName], [tbl_Contacts].[MiddleInitial], [tbl_Contacts].[LastName], [tbl_Contacts].[Suffix] And I want to create a FullName field in a view, but I can't have extra spaces if fields are blank...So I can't do FirstName + ' ' + MiddleInitial + ' ' + LastName + ' ' + Suffix...Because if there is no middle initial or suffix I'd have 2 extra spaces in the field. I think I need a Case statement, but I thought someone would have a handy method for this...Also, the middleinitial and suffix may be null.

    Read the article

  • Cakephp Autoconvert find() fields?

    - by Razor Storm
    In cake php I can grab a model's fields by using the find() method. What if I wish to apply a transformation function to the fields? Is there a way to directly accomplish this task? Suppose I have a model called RaceTime with the fields racerId and timeMillis RaceTime +------------+ | Field | +------------+ | id | | racerId | | timeMillis | +------------+ timeMillis is an int specifying how long the race took in milliseconds. Obviously saying a race took 15651 milliseconds isn't very useful to a human reader, and I would wish to convert this to a human readable format. Is there a way to accomplish this directly in find()? Or is the only option to loop through the results after find() finishes?

    Read the article

  • How can I combine a LINQ query with an IQueryable<Guid>

    - by John
    I have a LINQ query that uses 1 table + a large number of views. I'd like to be able to write something like this: IQueryable<Guid> mostViewedWriters; switch (datePicker) { case DatePicker.Last12Hours: mostViewedWriters = from x in context.tempMostViewed12Hours select x.GuidId; break; case DatePicker.Last24Hours: mostViewedWriters = from x in context.tempMostViewed12Hours select x.GuidId; break; case DatePicker.Last36Hours: mostViewedWriters = from x in context.tempMostViewed12Hours select x.GuidId; break; } var query = from x1 in context.Articles join x2 in context.Authors on x1.AuthorId == x2.AuthorId join x3 in mostViewedWriters on x2.AuthorId == x3.Id select new { x2.AuthorName, x1.ArticleId, x1.ArticleTitle }; The above C# is pseudo-code written to protect the innocent (me). The gist of the question is this: I have a query that is related to the results of a view. That view, however, could be one of many different views. All the views return the same data type. I thought that I might be able to create an IQueryable that would contain the Ids that I need and use that query. Alas, that effort has stalled.

    Read the article

  • Help needed for writing a Set Based query for finding the highest marks obtained by the students

    - by priyanka.sarkar_2
    I have the below table declare @t table (id int identity, name varchar(50),sub1 int,sub2 int,sub3 int,sub4 int) insert into @t select 'name1',20,30,40,50 union all select 'name2',10,30,40,50 union all select 'name3',40,60,100,50 union all select 'name4',80,30,40,80 union all select 'name5',80,70,40,50 union all select 'name6',10,30,40,80 The desired output should be Id Name Sub1 Sub2 Sub3 Sub4 3 Name3 100 4 Name4 80 80 5 Name5 80 70 6 Name6 80 What I have done so far is ;with cteSub1 as ( select rn1 = dense_rank() over(order by sub1 desc),t.id,t.name,t.sub1 from @t t ) ,cteSub2 as ( select rn2 = dense_rank() over(order by sub2 desc),t.id,t.name,t.sub2 from @t t ) ,cteSub3 as ( select rn3 = dense_rank() over(order by sub3 desc),t.id,t.name,t.sub3 from @t t ) ,cteSub4 as ( select rn4 = dense_rank() over(order by sub4 desc),t.id,t.name,t.sub4 from @t t ) select x1.id,x2.id,x3.id,x4.id ,x1.sub1,x2.sub2,x3.sub3,x4.sub4 from (select c1.id,c1.sub1 from cteSub1 c1 where rn1 =1) as x1 full join (select c2.id,c2.sub2 from cteSub2 c2 where rn2 =1)x2 on x1.id = x2.id full join (select c3.id,c3.sub3 from cteSub3 c3 where rn3 =1)x3 on x1.id = x3.id full join (select c4.id,c4.sub4 from cteSub4 c4 where rn4 =1)x4 on x1.id = x4.id which is giving me the output as id id id id sub1 sub2 sub3 sub4 5 5 NULL NULL 80 70 NULL NULL 4 NULL NULL 4 80 NULL NULL 80 NULL NULL 3 NULL NULL NULL 100 NULL NULL NULL NULL 6 NULL NULL NULL 80 Help needed. Also how can I reduce the number of CTE's?

    Read the article

< Previous Page | 669 670 671 672 673 674 675 676 677 678 679 680  | Next Page >