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• Looking for books

  - by robblot

  When I was learning Visual Basic.net 2008 I found a book that not only taught the basics but by the end of the book I had developed a fully working database application. Does anyone know where I might find a simular book but using Visual C++?

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• How do I replace NOT EXISTS with JOIN?

  - by YelizavetaYR

  I've got the following query: select distinct a.id, a.name from Employee a join Dependencies b on a.id = b.eid where not exists ( select * from Dependencies d where b.id = d.id and d.name = 'Apple' ) and exists ( select * from Dependencies c where b.id = c.id and c.name = 'Orange' ); I have two tables, relatively simple. The first Employee has an id column and a name column The second table Dependencies has 3 column, an id, an eid (employee id to link) and names (apple, orange etc). the data looks like this Employee table looks like this id | name ----------- 1 | Pat 2 | Tom 3 | Rob 4 | Sam Dependencies id | eid | Name -------------------- 1 | 1 | Orange 2 | 1 | Apple 3 | 2 | Strawberry 4 | 2 | Apple 5 | 3 | Orange 6 | 3 | Banana As you can see Pat has both Orange and Apple and he needs to be excluded and it has to be via joins and i can't seem to get it to work. Ultimately the data should only return Rob

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• triggers for generating userID based on user's information.

  - by nectar

  I have complaint table 1. tblProfile with columns userId | name | age | address | mobileno | 2. tblUserId with columns userId | role | status now when user fills the form I want to insert one row in tblProfile, before inserting a new row I want to create userId by combining starting letters of name and mobile no and then insert into tblprofile with userId after this I want to insert that UserId into tblUserId table. for this I have to use two triggers one is before insert trigger and another is after insert trigger.but I dont know how to capture user information to create userId and how to pass that Id to second trigger.

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• count(*) is it really expensive ?

  - by Anil Namde

  I have a page where i have 4 tabs displaying 4 different reports based of different tables. Now i get row count of each tabled using select count() from table query and display number of rows available in each table on the tabs. Now with each page post back 5 count() queries are executed (4 to get counts and 1 for pagination) and 1 query for getting report. Now my question is should is count(*) query really expensive that i should keep the row counts (at least which are displayed on tab) in view state of page instead of queering each time? How much expensive it is ?

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• CTE to build a list of departments and managers (hierarchical)

  - by Milky Joe

  I need to generate a list of users that are managers, or managers of managers, for company departments. I have two tables; one details the departments and one contains the manager hierarchy (simplified): CREATE TABLE [dbo].[Manager]( [ManagerId] [int], [ParentManagerId] [int]) CREATE TABLE [dbo].[Department]( [DepartmentId] [int], [ManagerId] [int]) Basically, I'm trying to build a CTE that will give me a list of DepartmentIds, together with all ManagerIds that are in the manager hierarchy for that department. So... Say Manager 1 is the Manager for Department 1, and Manager 2 is Manager 1's Manager, and Manager 3 is Manager 2's Manager, I'd like to see: DepartmentId, ManagerId 1, 1 1, 2 1, 3 Basically, managers are able to deal with all of their sub-manager's departments. Building the CTE to return the Manager hierarchy was fairly simple, but I'm struggling to inject the Departments in there: WITH DepartmentManagers AS ( SELECT ManagerId, ParentManagerId, 0 AS Depth From Manager UNION ALL SELECT Manager.ManagerId, Manager.ParentManagerId, DepartmentManagers.Depth + 1 AS Depth FROM Manager INNER JOIN DepartmentManagers ON DepartmentManagers.ManagerId = Manager.ParentManagerId ) Can anyone help?

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• MySQL - Structure for Permissions to Objects

  - by Kerry

  What would be an ideal structure for users permissions of objects. I've seen many related posts for general permissions, or what sections a user can access, which consists of a users, userGroups and userGroupRelations or something of that nature. In my system there are many different objects that can get created, and each one has to be able to be turned on or off. For instance, take a password manager that has groups and sub groups. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Group 9 Group 10 Each group can contain a set of passwords. A user can be given read, write, edit and delete permissions to any group. More groups can get created at any point in time. If someone has permission to a group, I should be able to make him have permissions to all sub groups OR restrict it to just that group. My current thought is to have a users table, and then a permissions table with columns like: permission_id (int) PRIMARY_KEY user_id (int) INDEX object_id (int) INDEX type (varchar) INDEX read (bool) write (bool) edit (bool) delete (bool) This has worked in the past, but the new system I'm building needs to be able to scale rapidly, and I am unsure if this is the best structure. It also makes the idea of having someone with all subgroup permissions of a group more difficult. So, as a question, should I use the above structure? Or can someone point me in the direction of a better one?

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• How to prune data set by frequency to conform to paper's description

  - by sakura90

  The MovieLens data set provides a table with columns: userid | movieid | tag | timestamp I have trouble reproducing the way they pruned the MovieLens data set used in: Tag Informed Collaborative Filtering, by Zhen, Li and Young In 4.1 Data Set of the above paper, it writes "For the tagging information, we only keep those tags which are added on at least 3 distinct movies. As for the users, we only keep those users who used at least 3 distinct tags in their tagging history. For movies, we only keep those movies that are annotated by at least 3 distinct tags." I tried to query the database: select TMP.userid, count(*) as tagnum from (select distinct T.userid as userid, T.tag as tag from tags T) AS TMP group by TMP.userid having tagnum >= 3; I got a list of 1760 users who labeled 3 distinct tags. However, some of the tags are not added on at least 3 distinct movies. Any help is appreciated.

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• mysqli_stmt_bind_param SQL Injection

  - by profitphp

  Is there still an injection risk when using prepared statements and mysqli_stmt_bind_param? For example: $malicious_input = 'bob"; drop table users'; mysqli_stmt_bind_param($stmt, 's', $malicious_input); Behind the scenes does mysqli_stmt_bind_param pass this query string to mysql: SET @username = "bob"; drop table users"; Or does it perform the SET command through the API, or use some type of protection to keep this from happening?

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• Synchronise structure of multiple database

  - by phenevo

  Hi, I have 2 database: production and to test. Production should have the same fields and tables like testdatabase. is there any software, or script to show difference between this two databases?

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• MySQL: Count occurrences of known (or enumerated) distinct values

  - by Eilidh

  After looking at how to count the occurrences of distinct values in a field, I am wondering how to count the occurrences of each distinct value if the distinct values are known (or enumerated). For example, if I have a simple table - TrafficLight Colour ------------ ------ 1 Red 2 Amber 3 Red 4 Red 5 Green 6 Green where one column (in this case Colour) has known (or enumerated) distinct values, how could I return the count for each colour as a separate value, rather than as an array, as in the linked example. To return an array with a count of each colour (using the same method as in the linked example), the query would be something like SELECT Colour COUNT(*) AS ColourCount FROM TrafficLights GROUP BY Colour, and return an array - Colour ColourCount ------ ----------- Red 3 Amber 1 Green 2 What I would like to do is to return the count for each Colour AS a separate total (e.g. RedCount). How can I do this?

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• Custom SQL function for NHibernate dialect

  - by Kristoffer Ahl

  I want to be able to call a custom function called "recent_date" as part of my HQL. Like this: [Date] >= recent_date() I created a new dialect, inheriting from MsSql2000Dialect and specified the dialect for my configuration. public class NordicMsSql2000Dialect : MsSql2000Dialect { public NordicMsSql2000Dialect() { RegisterFunction( "recent_date", new SQLFunctionTemplate( NHibernateUtil.Date, "dateadd(day, -15, getdate())" ) ); } } var configuration = Fluently.Configure() .Database( MsSqlConfiguration.MsSql2000 .ConnectionString(c => .... ) .Cache(c => c.UseQueryCache().ProviderClass<HashtableCacheProvider>()) .Dialect<NordicMsSql2000Dialect>() ) .Mappings(m => ....) .BuildConfiguration(); When calling recent_date() I get the following error: System.Data.SqlClient.SqlException: 'recent_date' is not a recognized function name I'm using it in a where statement for a HasMany-mapping like below. HasMany(x => x.RecentValues) .Access.CamelCaseField(Prefix.Underscore) .Cascade.SaveUpdate() .Where("Date >= recent_date()"); What am I missing here?

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• How can I make a multi search SPROC/UDF by passing a tabled-value to it?

  - by Shimmy

  I actually want to achieve the following description This is the table argument I want to pass to the server <items> <item category="cats">1</item> <item category="dogs">2</item> </items> SELECT * FROM Item WHERE Item.Category = <one of the items in the XML list> AND Item.ReferenceId = <the corresponding value of that item xml element> --Or in other words: SELECT FROM Items WHERE Item IN XML according to the splecified columns. Am I clear enought? I don't mind to do it in a different way other than xml. What I need is selecting values that mach an array of two of its columns' values.

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• Accessing non-related entities in LinqToSql entity classes

  - by Chris Johnson

  In LinqToSql, if I want to access a non-related entity in an entity partial class, how do I do this without creating a new DataContext? Here's the scenario: I have the tables Client, IssueType and ClientIssueType. A Client may specify a list of IssueTypes if they do not want to use the default IssueTypes. I have the default IssueTypes in the ClientIssueType table with a ClientId of null. In my Client partial I'd like to try to retrieve all IssueTypes, and if none are found, return all default IssueTypes. The only way I can see of accessing the IssueTypes with a null ClientId is by accessing the table through a new DataContext, which is problematic once I want to start assigning them to Issues. Where am I going wrong?

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• Generate dynamic UPDATE command from Expression<Func<T, T>>

  - by Rui Jarimba

  I'm trying to generate an UPDATE command based on Expression trees (for a batch update). Assuming the following UPDATE command: UPDATE Product SET ProductTypeId = 123, ProcessAttempts = ProcessAttempts + 1 For an expression like this: Expression<Func<Product, Product>> updateExpression = entity => new Product() { ProductTypeId = 123, ProcessAttempts = entity.ProcessAttempts + 1 }; How can I generate the SET part of the command? SET ProductTypeId = 123, ProcessAttempts = ProcessAttempts + 1

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• how to avoid sub-query to gain performance

  - by chun

  hi i have a reporting query which have 2 long sub-query SELECT r1.code_centre, r1.libelle_centre, r1.id_equipe, r1.equipe, r1.id_file_attente, r1.libelle_file_attente,r1.id_date, r1.tranche, r1.id_granularite_de_periode,r1.granularite, r1.ContactsTraites, r1.ContactsenParcage, r1.ContactsenComm, r1.DureeTraitementContacts, r1.DureeComm, r1.DureeParcage, r2.AgentsConnectes, r2.DureeConnexion, r2.DureeTraitementAgents, r2.DureePostTraitement FROM ( SELECT cc.id_centre_contact, cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe, a.id_file_attente, f.libelle_file_attente, a.id_date, g.tranche, g.id_granularite_de_periode, g.granularite, sum(Nb_Contacts_Traites) as ContactsTraites, sum(Nb_Contacts_en_Parcage) as ContactsenParcage, sum(Nb_Contacts_en_Communication) as ContactsenComm, sum(Duree_Traitement/1000) as DureeTraitementContacts, sum(Duree_Communication / 1000 + Duree_Conference / 1000 + Duree_Com_Interagent / 1000) as DureeComm, sum(Duree_Parcage/1000) as DureeParcage FROM agr_synthese_activite_media_fa_agent a, centre_contact cc, direction_contact dc, granularite_de_periode g, media m, file_attente f WHERE m.id_media = a.id_media AND cc.id_centre_contact = a.id_centre_contact AND a.id_direction_contact = dc.id_direction_contact AND dc.direction_contact ='INCOMING' AND a.id_file_attente = f.id_file_attente AND m.media = 'PHONE' AND ( ( g.valeur_min = date_format(a.id_date,'%d/%m') and g.granularite = 'Jour') or ( g.granularite = 'Heure' and a.id_th_heure = g.id_granularite_de_periode) ) GROUP by cc.id_centre_contact, a.id_equipe, a.id_file_attente, a.id_date, g.tranche, g.id_granularite_de_periode) r1, ( (SELECT cc.id_centre_contact,cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe, a.id_date, g.tranche, g.id_granularite_de_periode,g.granularite, count(distinct a.id_agent) as AgentsConnectes, sum(Duree_Connexion / 1000) as DureeConnexion, sum(Duree_en_Traitement / 1000) as DureeTraitementAgents, sum(Duree_en_PostTraitement / 1000) as DureePostTraitement FROM activite_agent a, centre_contact cc, granularite_de_periode g WHERE ( g.valeur_min = date_format(a.id_date,'%d/%m') and g.granularite = 'Jour') AND cc.id_centre_contact = a.id_centre_contact GROUP BY cc.id_centre_contact, a.id_equipe, a.id_date, g.tranche, g.id_granularite_de_periode ) UNION (SELECT cc.id_centre_contact,cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe, a.id_date, g.tranche, g.id_granularite_de_periode,g.granularite, count(distinct a.id_agent) as AgentsConnectes, sum(Duree_Connexion / 1000) as DureeConnexion, sum(Duree_en_Traitement / 1000) as DureeTraitementAgents, sum(Duree_en_PostTraitement / 1000) as DureePostTraitement FROM activite_agent a, centre_contact cc, granularite_de_periode g WHERE ( g.granularite = 'Heure' AND a.id_th_heure = g.id_granularite_de_periode) AND cc.id_centre_contact = a.id_centre_contact GROUP BY cc.id_centre_contact,a.id_equipe, a.id_date, g.tranche, g.id_granularite_de_periode) ) r2 WHERE r1.id_centre_contact = r2.id_centre_contact AND r1.id_equipe = r2.id_equipe AND r1.id_date = r2.id_date AND r1.tranche = r2.tranche AND r1.id_granularite_de_periode = r2.id_granularite_de_periode GROUP BY r1.id_centre_contact , r1.id_equipe, r1.id_file_attente, r1.id_date, r1.tranche, r1.id_granularite_de_periode ORDER BY r1.code_centre, r1.libelle_centre, r1.equipe, r1.libelle_file_attente, r1.id_date, r1.id_granularite_de_periode,r1.tranche the EXPLAIN shows | id | select_type | table | type| possible_keys | key | key_len | ref| rows | Extra | '1', 'PRIMARY', '<derived3>', 'ALL', NULL, NULL, NULL, NULL, '2520', 'Using temporary; Using filesort' '1', 'PRIMARY', '<derived2>', 'ALL', NULL, NULL, NULL, NULL, '4378', 'Using where; Using join buffer' '3', 'DERIVED', 'a', 'ALL', 'fk_Activite_Agent_centre_contact', NULL, NULL, NULL, '83433', 'Using temporary; Using filesort' '3', 'DERIVED', 'g', 'ref', 'Index_granularite,Index_Valeur_min', 'Index_Valeur_min', '23', 'func', '1', 'Using where' '3', 'DERIVED', 'cc', 'ALL', 'PRIMARY', NULL, NULL, NULL, '6', 'Using where; Using join buffer' '4', 'UNION', 'g', 'ref', 'PRIMARY,Index_granularite', 'Index_granularite', '23', '', '24', 'Using where; Using temporary; Using filesort' '4', 'UNION', 'a', 'ref', 'fk_Activite_Agent_centre_contact,fk_activite_agent_TH_heure', 'fk_activite_agent_TH_heure', '5', 'reporting_acd.g.Id_Granularite_de_periode', '2979', 'Using where' '4', 'UNION', 'cc', 'ALL', 'PRIMARY', NULL, NULL, NULL, '6', 'Using where; Using join buffer' NULL, 'UNION RESULT', '<union3,4>', 'ALL', NULL, NULL, NULL, NULL, NULL, '' '2', 'DERIVED', 'g', 'range', 'PRIMARY,Index_granularite,Index_Valeur_min', 'Index_granularite', '23', NULL, '389', 'Using where; Using temporary; Using filesort' '2', 'DERIVED', 'a', 'ALL', 'fk_agr_synthese_activite_media_fa_agent_centre_contact,fk_agr_synthese_activite_media_fa_agent_direction_contact,fk_agr_synthese_activite_media_fa_agent_file_attente,fk_agr_synthese_activite_media_fa_agent_media,fk_agr_synthese_activite_media_fa_agent_th_heure', NULL, NULL, NULL, '20903', 'Using where; Using join buffer' '2', 'DERIVED', 'cc', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Centre_Contact', '1', '' '2', 'DERIVED', 'f', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_File_Attente', '1', '' '2', 'DERIVED', 'dc', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Direction_Contact', '1', 'Using where' '2', 'DERIVED', 'm', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Media', '1', 'Using where' don't know it very clear, but i think is the problem of seems it take full scaning than i change all the sub-query to views(create view as select sub-query), and the result is the same thanks for any advice

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• Database indexes and their Big-O notation

  - by miket2e

  I'm trying to understand the performance of database indexes in terms of Big-O notation. Without knowing much about it, I would guess that: Querying on a primary key or unique index will give you a O(1) lookup time. Querying on a non-unique index will also give a O(1) time, albeit maybe the '1' is slower than for the unique index (?) Querying on a column without an index will give a O(N) lookup time (full table scan). Is this generally correct ? Will querying on a primary key ever give worse performance than O(1) ? My specific concern is for SQLite, but I'd be interested in knowing to what extent this varies between different databases too.

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• Meaning of tA tC and tP

  - by Greg Wiley

  If this is a duplicate I appoligize, but looking for two-letter strings is quite hard in any search. I'm looking for the meaning of tA tC and tP in the context of a mysql query. And in the spirit of "teaching a man how to fish" it would be great if you could point me in the right direction of where to find this info in the future. Edit: The Query $wpdb->get_row($wpdb->prepare("SELECT tA.* FROM ".AMYLITE_ADS." tA, ".AMYLITE_ADS_CAMPAIGNS." tC, ".AMYLITE_PACKAGES." tP WHERE tA.id=tC.ad_id AND tC.campaign_id=tP.campaign_id AND tP.zone_id=%d AND tP.date_end>CURDATE() GROUP BY tA.id ORDER BY RAND()", $zone->id));

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• I want to run two or more procedures in parallel

  - by binod gyawali

  I have list of procedures. All procedures are not dependent upon each other. So, I need to do is, to run the independent procedures in parallel. I have 4 procedures that are to be run parallel. When the procedures are run successfully, now I need to go to the next task. These procedures create about 10 tables. Next task is to execute the set of procedures. I have made one table, where I describe the dependency of these procedures to the tables created above. After any one of the above procedures is completed, I should come to this set of procedures, and find out those procedures whose dependency tables are already created. If any procedure whose dependent tables creation is completed, I need to execute this procedure. Running 4 procedures parallel is done by dts. But, difficulty for me is to transfer the task from the above 4 procedures to the below set of procedures. Please help me to complete my task. Thanks in advance

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• SQLite - ON DUPLICATE KEY UPDATE

  - by Alix Axel

  MySQL has something like this: INSERT INTO visits (ip, hits) VALUES ('127.0.0.1', 1) ON DUPLICATE KEY UPDATE hits = hits + 1; As far as I'm know this feature doesn't exist in SQLite, what I want to know is if there is any way to archive the same effect without having to execute two queries. Also, if this is not possible, what do you prefer: SELECT + (INSERT or UPDATE) or UPDATE (+ INSERT if UPDATE fails)

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• get output of last Process on SSAS cube

  - by Raj More

  I have processed a SSAS cube. After it was done processing, I hit the close button - and then realized that I should have saved the output. I think SSAS stores the processing log as a text or XML file, but I do not know what folder to look into. Can someone direct me to retrieving processing logs?

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• how to implement undo operation in datagridview

  - by ush

  Hi, I have created one application in c#.net.Using this application we can update datagridview,now i need to implement undo in it plz give me some ideas. private void button29_Click(object sender, EventArgs e) { Datatable dt; dt.RejectChanges(); } using above code i can do undo before updating. but i need a undo feature as in word plz suggest me thanks in advance

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• Oracle (Old?) Joins

  - by Grasper

  I have been porting oracle selects, and I have been running across a lot of queries like so: SELECT e.last_name, d.department_name FROM employees e, departments d WHERE e.department_id(+) = d.department_id; ...and: SELECT last_name, d.department_id FROM employees e, departments d WHERE e.department_id = d.department_id(+); Are there any guides/tutorials for converting all of the variants of the (+) syntax? What is that syntax even called (so I can scour google)? When was this standard phased out? Any info is appreciated.

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• sybase - values from one table that aren't on another, on opposite ends of a 3-table join

  - by Lazy Bob

  Hypothetical situation: I work for a custom sign-making company, and some of our clients have submitted more sign designs than they're currently using. I want to know what signs have never been used. 3 tables involved: table A - signs for a company sign_pk(unique) | company_pk | sign_description 1 --------------------1 ---------------- small 2 --------------------1 ---------------- large 3 --------------------2 ---------------- medium 4 --------------------2 ---------------- jumbo 5 --------------------3 ---------------- banner table B - company locations company_pk | company_location(unique) 1 ------|------ 987 1 ------|------ 876 2 ------|------ 456 2 ------|------ 123 table C - signs at locations (it's a bit of a stretch, but each row can have 2 signs, and it's a one to many relationship from company location to signs at locations) company_location | front_sign | back_sign 987 ------------ 1 ------------ 2 987 ------------ 2 ------------ 1 876 ------------ 2 ------------ 1 456 ------------ 3 ------------ 4 123 ------------ 4 ------------ 3 So, a.company_pk = b.company_pk and b.company_location = c.company_location. What I want to try and find is how to query and get back that sign_pk 5 isn't at any location. Querying each sign_pk against all of the front_sign and back_sign values is a little impractical, since all the tables have millions of rows. Table a is indexed on sign_pk and company_pk, table b on both fields, and table c only on company locations. The way I'm trying to write it is along the lines of "each sign belongs to a company, so find the signs that are not the front or back sign at any of the locations that belong to the company tied to that sign." My original plan was: Select a.sign_pk from a, b, c where a.company_pk = b.company_pk and b.company_location = c.company_location and a.sign_pk *= c.front_sign group by a.sign_pk having count(c.front_sign) = 0 just to do the front sign, and then repeat for the back, but that won't run because c is an inner member of an outer join, and also in an inner join. This whole thing is fairly convoluted, but if anyone can make sense of it, I'll be your best friend.

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• How can I display an Error Message when my program can't connect to database?

  - by Rafael

  Hi, I need to know a way to show a message or something like that when I compile my program and the user or password are wrong, because when I do this nothing happens. I'm making a system that save logs. log4net just using C#. if you can help me I'd appreciate. thanks!

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• Select a row having a column with max value - On a date range

  - by Abhi

  Excuse me for posting a similar question. Please consider this: date value 18/5/2010, 1 pm 40 18/5/2010, 2 pm 20 18/5/2010, 3 pm 60 18/5/2010, 4 pm 30 18/5/2010, 5 pm 60 18/5/2010, 6 pm 25 19/5/2010, 6 pm 300 19/5/2010, 6 pm 450 19/5/2010, 6 pm 375 20/5/2010, 6 pm 250 20/5/2010, 6 pm 310 The query is to get the date and value for each day such that the value obtained for that day is max. If the max value is repeated on that day, the lowest time stamp is selected. The result should be like: 18/5/2010, 3 pm 60 19/5/2010, 6 pm 450 20/5/2010, 6 pm 310 The query should take in a date range like the one given below and find results for that range in the above fashion: where date = to_date('26/03/2010','DD/MM/YYYY') AND date < to_date('27/03/2010','DD/MM/YYYY')

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