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• Database Modeling - Either/Or in Many-to-Many

  - by EkoostikMartin

  I have an either/or type of situation in a many-to-many relationship I'm trying to model. So I have these tables: Message ---- *MessageID MessageText Employee ---- *EmployeeID EmployeeName Team ---- *TeamID TeamName MessageTarget ---- MessageID EmployeeID (nullable) TeamID (nullable) So, a Message can have either a list of Employees, or a list of Teams as a MessageTarget. Is the MessageTarget table I have above the best way to implement this relationship? What constraints can I place on the MessageTarget effectively? How should I create a primary key on MessageTarget table?

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• SQL Concurrent test update question

  - by ptoinson

  Howdy Folks, I have a SQLServer 2008 database in which I have a table for Tags. A tag is just an id and a name. The definition of the tags table looks like: CREATE TABLE [dbo].[Tag]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](255) NOT NULL CONSTRAINT [PK_Tag] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) Name is also a unique index. further I have several processes adding data to this table at a pretty rapid rate. These processes use a stored proc that looks like: ALTER PROC [dbo].[lg_Tag_Insert] @Name varchar(255) AS DECLARE @ID int SET @ID = (select ID from Tag where Name=@Name ) if @ID is null begin INSERT Tag(Name) VALUES (@Name) RETURN SCOPE_IDENTITY() end else begin return @ID end My issues is that, other than being a novice at concurrent database design, there seems to be a race condition that is causing me to occasionally get an error that I'm trying to enter duplicate keys (Name) into the DB. The error is: Cannot insert duplicate key row in object 'dbo.Tag' with unique index 'IX_Tag_Name'. This makes sense, I'm just not sure how to fix this. If it where code I would know how to lock the right areas. SQLServer is quite a different beast. First question is what is the proper way to code this 'check, then update pattern'? It seems I need to get an exclusive lock on the row during the check, rather than a shared lock, but it's not clear to me the best way to do that. Any help in the right direction will be greatly appreciated. Thanks in advance.

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• Sending changes from multiple tables in disconnected dataset to SQLServer...

  - by Stecy

  We have a third party application that accept calls using an XML RPC mechanism for calling stored procs. We send a ZIP-compressed dataset containing multiple tables with a bunch of update/delete/insert using this mechanism. On the other end, a CLR sproc decompress the data and gets the dataset. Then, the following code gets executed: using (var conn = new SqlConnection("context connection=true")) { if (conn.State == ConnectionState.Closed) conn.Open(); try { foreach (DataTable table in ds.Tables) { string columnList = ""; for (int i = 0; i < table.Columns.Count; i++) { if (i == 0) columnList = table.Columns[0].ColumnName; else columnList += "," + table.Columns[i].ColumnName; } var da = new SqlDataAdapter("SELECT " + columnList + " FROM " + table.TableName, conn); var builder = new SqlCommandBuilder(da); builder.ConflictOption = ConflictOption.OverwriteChanges; da.RowUpdating += onUpdatingRow; da.Update(ds, table.TableName); } } catch (....) { ..... } } Here's the event handler for the RowUpdating event: public static void onUpdatingRow(object sender, SqlRowUpdatingEventArgs e) { if ((e.StatementType == StatementType.Update) && (e.Command == null)) { e.Command = CreateUpdateCommand(e.Row, sender as SqlDataAdapter); e.Status = UpdateStatus.Continue; } } and the CreateUpdateCommand method: private static SqlCommand CreateUpdateCommand(DataRow row, SqlDataAdapter da) { string whereClause = ""; string setClause = ""; SqlConnection conn = da.SelectCommand.Connection; for (int i = 0; i < row.Table.Columns.Count; i++) { char quoted; if ((row.Table.Columns[i].DataType == Type.GetType("System.String")) || (row.Table.Columns[i].DataType == Type.GetType("System.DateTime"))) quoted = '\''; else quoted = ' '; string val = row[i].ToString(); if (row.Table.Columns[i].DataType == Type.GetType("System.Boolean")) val = (bool)row[i] ? "1" : "0"; bool isPrimaryKey = false; for (int j = 0; j < row.Table.PrimaryKey.Length; j++) { if (row.Table.PrimaryKey[j].ColumnName == row.Table.Columns[i].ColumnName) { if (whereClause != "") whereClause += " AND "; if (row[i] == DBNull.Value) whereClause += row.Table.Columns[i].ColumnName + "=NULL"; else whereClause += row.Table.Columns[i].ColumnName + "=" + quoted + val + quoted; isPrimaryKey = true; break; } } /* Only values for column that is not a primary key can be modified */ if (!isPrimaryKey) { if (setClause != "") setClause += ", "; if (row[i] == DBNull.Value) setClause += row.Table.Columns[i].ColumnName + "=NULL"; else setClause += row.Table.Columns[i].ColumnName + "=" + quoted + val + quoted; } } return new SqlCommand("UPDATE " + row.Table.TableName + " SET " + setClause + " WHERE " + whereClause, conn); } However, this is really slow when we have a lot of records. Is there a way to optimize this or an entirely different way to send lots of udpate/delete on several tables? I would really much like to use TSQL for this but can't figure a way to send a dataset to a regular sproc. Additional notes: We cannot directly access the SQLServer database. We tried without compression and it was slower.

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• Oracle - Parameterized Query has EXECUTIONS = PARSE_CALLS

  - by Cory Grimster

  We have a .NET application talking to Oracle 10g. Our DBA recently pulled a list of queries where executions is equal to parse_calls. We assumed that this would help us find all of the unparameterized queries in our code. Unexpectedly, the following query showed up near the top of this list, with 1,436,169 executions and 1,436,151 parses: SELECT bar.foocolumn FROM bartable bar, baztable baz WHERE bar.some_id = :someId AND baz.another_id = :anotherId AND baz.some_date BETWEEN bar.start_date AND (nvl(bar.end_date, baz.some_date + (1/84600)) - (1/84600)) Why is executions equal to parse_calls for this query?

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• Why would you Truncate immediately before Dropping a temp table?

  - by d03boy

  I see some code where the author has truncated a temp table immediately before dropping the temp table. Is there a reason for doing this? TRUNCATE TABLE #Temp DROP TABLE #Temp

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• Tables with no Primary Key

  - by Matt Hamilton

  I have several tables whose only unique data is a uniqueidentifier (a Guid) column. Because guids are non-sequential (and they're client-side generated so I can't use newsequentialid()), I have made a non-primary, non-clustered index on this ID field rather than giving the tables a clustered primary key. I'm wondering what the performance implications are for this approach. I've seen some people suggest that tables should have an auto-incrementing ("identity") int as a clustered primary key even if it doesn't have any meaning, as it means that the database engine itself can use that value to quickly look up a row instead of having to use a bookmark. My database is merge-replicated across a bunch of servers, so I've shied away from identity int columns as they're a bit hairy to get right in replication. What are your thoughts? Should tables have primary keys? Or is it ok to not have any clustered indexes if there are no sensible columns to index that way?

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• Any code quality tool for pl/sql?

  - by Serkan Kasapbasi

  Hi, is there any tool, library that can analyze plsql code, like PMD/CheckStyle do for Java ?

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• How the return type is determined in a method that uses Linq2Sql?

  - by Richard77

  Hello, I've usually have difficulties with return types when it comes to linq. I'll explain by the following examples. Let's say I have a Table Products with ProductID, Name, Category, and Price as columns : 1) IQueryable<Product public IQueryable<Product> GetChildrenProducts() { return (from pd in db.Products where pd.Category == "Children" select pd); } 2) Product public Product GetProduct(int id) { return (from pd in db.Products where pd.ProductID == id select pd).FirstOrDefault(); } Now, if I decide to select, for instance, only one column (Price or Name) or even 2 or 3 columns (Name and Price), but in any case, less than the 4 columns, what's going to be the return type? I mean this: public returnType GetSomeInformation() { return (from pd in db.Products select new { pd.Name, pd.Price } } What SHOULD BE the returnType for the GetSomeInformation()? Thanks for helping

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• Result Set Problem

  - by vipul

  Hello Friends, It is possible to Use two query with in single ResultSet

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• Best way to store sales tax information

  - by Seph

  When designing a stock management database system (sales / purchases) what would be the best way to store the various taxes and other such amounts? A few of the fields that could be saved are: Unit price excluding tax Unit price including tax Tax per item Total excluding tax (rounded to 2 decimals) Total including tax (rounded to 2 decimals) Total tax (rounded to 2 decimals) Currently the most reasonable solution so far is storing down (roughly) item, quantity, total excluding tax (rounded) and the total tax (rounded). Can anyone suggest some better way of storing this details for a generic system? Also, given the system needs to be robust, what should be done if there were multiple tax values (eg: state and city) which might need to be separated, in this case a separate table would be in order, but would it be considered excessive to just have a rowID and some taxID mapping to a totalTax column?

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• Can't return a List from a Compiled Query.

  - by Andrew

  I was speeding up my app by using compiled queries for queries which were getting hit over and over. I tried to implement it like this: Function Select(ByVal fk_id As Integer) As List(SomeEntity) Using db As New DataContext() db.ObjectTrackingEnabled = False Return CompiledSelect(db, fk_id) End Using End Function Shared CompiledSelect As Func(Of DataContext, Integer, List(Of SomeEntity)) = _ CompiledQuery.Compile(Function(db As DataContext, fk_id As Integer) _ (From u In db.SomeEntities _ Where u.SomeLinkedEntity.ID = fk_id _ Select u).ToList()) This did not work and I got this error message: Type : System.ArgumentNullException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Message : Value cannot be null. Parameter name: value However, when I changed my compiled query to return IQueryable instead of List like so: Function Select(ByVal fk_id As Integer) As List(SomeEntity) Using db As New DataContext() db.ObjectTrackingEnabled = False Return CompiledSelect(db, fk_id).ToList() End Using End Function Shared CompiledSelect As Func(Of DataContext, Integer, IQueryable(Of SomeEntity)) = _ CompiledQuery.Compile(Function(db As DataContext, fk_id As Integer) _ From u In db.SomeEntities _ Where u.SomeLinkedEntity.ID = fk_id _ Select u) It worked fine. Can anyone shed any light as to why this is? BTW, compiled queries rock! They sped up my app by a factor of 2.

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• How to designing a generic databse whos layout may change over time?

  - by mawg

  Here's a tricky one - how do I programatically create and interrogate a database who's contents I can't really foresee? I am implementing a generic input form system. The user can create PHP forms with a WYSIWYG layout and use them for any purpose he wishes. He can also query the input. So, we have three stages: a form is designed and generated. This is a one-off procedure, although the form can be edited later. This designs the database. someone or several people make use of the form - say for daily sales reports, stock keeping, payroll, etc. Their input to the forms is written to the database. others, maybe management, can query the database and generate reports. Since these forms are generic, I can't predict the database structure - other than to say that it will reflect HTML form fields and consist of a the data input from collection of edit boxes, memos, radio buttons and the like. Questions and remarks: A) how can I best structure the database, in terms of tables and columns? What about primary keys? My first thought was to use the control name to identify each column, then I realized that the user can edit the form and rename, so that maybe "name" becomes "employee" or "wages" becomes ":salary". I am leaning towards a unique number for each. B) how best to key the rows? I was thinking of a timestamp to allow me to query and a column for the row Id from A) C) I have to handle column rename/insert/delete. Foe deletion, I am unsure whether to delete the data from the database. Even if the user is not inputting it from the form any more he may wish to query what was previously entered. Or there may be some legal requirements to retain the data. Any gotchas in column rename/insert/delete? D) For the querying, I can have my PHP interrogate the database to get column names and generate a form with a list where each entry has a database column name, a checkbox to say if it should be used in the query and, based on column type, some selection criteria. That ought to be enough to build searches like "position = 'senior salesman' and salary 50k". E) I probably have to generate some fancy charts - graphs, histograms, pie charts, etc for query results of numerical data over time. I need to find some good FOSS PHP for this. F) What else have I forgotten? This all seems very tricky to me, but I am database n00b - maybe it is simple to you gurus?

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• LINQtoSQL Custom Constructor off Partial Class?

  - by sah302

  Hi all, I read this question here: http://stackoverflow.com/questions/82409/is-there-a-way-to-override-the-empty-constructor-in-a-class-generated-by-linqtosq Typically my constructor would look like: public User(String username, String password, String email, DateTime birthday, Char gender) { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, as read in that question, you want to use partial method OnCreated() instead to assign values and not overwrite the default constructor. Okay so I got this : partial void OnCreated() { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, this gives me two errors: Partial Methods must be declared private. Partial Methods must have empty method bodies. Alright I change it to Private Sub OnCreated() to remove both of those errors. However I am still stuck with...how can I pass it values as I would with a normal custom constructor? Also I am doing this in VB (converted it since I know most know/prefer C#), so would that have an affect on this?

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• Passing multiple values for a single parmeter in Reporting Services

  - by Scott and the Dev Team

  I have several Multi-Select parameters in my report. I am trying to find a way to pass in multiple values for a single parameter in the web query string? If I pass in a single value, it works fine. The report runs fine selecting multiple choices for a single param. My trouble lies in the web query string.

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• Aggregate Functions on subsets of data based on current row values with SQL

  - by aasukisuki

  Hopefully that title makes sense... Let's say I have an employee table: ID | Name | Title | Salary ---------------------------- 1 | Bob | Manager | 15285 2 | Joe | Worker | 10250 3 | Al | Worker | 11050 4 | Paul | Manager | 16025 5 | John | Worker | 10450 What I'd like to do is write a query that will give me the above table, along with an averaged salary column, based on the employee title: ID | Name | Title | Salary | Pos Avg -------------------------------------- 1 | Bob | Manager | 15285 | 15655 2 | Joe | Worker | 10250 | 10583 3 | Al | Worker | 11050 | 10583 4 | Paul | Manager | 16025 | 15655 5 | John | Worker | 10450 | 10583 I've tried doing this with a sub-query along the lines of: Select *, (select Avg(e2.salary) from employee e2 where e2.title = e.title) from employee e But I've come to realize that the sub-query is executed first, and has no knowledge of the table alias'd e I'm sure I'm missing something REALLY obvious here, can anyone point me in the right diretion?

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• Why Banks or Financial Companies prefer Oracle than other RDBMS for their "Core" systems?

  - by edwin.nathaniel

  I'd like to know why most Banks or Financial companies prefer Oracle than other RDBMS for their core systems (the absolutely minimum features that a Bank must support). I found a few answers that didn't satisfy me. For example: Oracle has more features. But features for what? Can't you implement that in application level if you were not using Oracle? Could someone please describe a bit more technical but still on high-level overview of what the bank needs and how Oracle would solve it and the others can't or don't have the features yet? I came from the web-app (web 2.0) crowd who normally hear news about MySQL, PostgreSQL or even key-value/column-oriented storage solution. I have almost zero knowledge on how Banks or Financial companies operates from technical perspective. Thank you, Ed

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• Not getting the right expected output for my Mysql Query?

  - by user1878107

  i've 4 tables as shown below doctors id name ------------ 1 Mathew 2 Praveen 3 Rosie 4 Arjun 5 Denis doctors_appointments id doctors_id patient_name contact date status -------------------------------------------------------------------------------------- 1 5 Nidhin 9876543210 2012-12-10 15:39:41 Registered 2 5 Sunny 9876543210 2012-12-18 15:39:48 Registered 3 5 Mani 9876543210 2012-12-12 15:39:57 Registered 4 2 John 9876543210 2012-12-24 15:40:09 Registered 5 4 Raj 9876543210 2012-12-05 15:41:57 Registered 6 3 Samuel 9876543210 2012-12-14 15:41:33 Registered 7 2 Louis 9876543210 2012-12-24 15:40:23 Registered 8 1 Federick 9876543210 2012-12-28 15:41:05 Registered 9 2 Sam 9876543210 2012-12-12 15:40:38 Registered 10 4 Sita 9876543210 2012-12-12 15:41:00 Registered doctors_dutyplan id doctor_id weeks time no_of_patients ------------------------------------------------------------------ 1 1 3,6,7 9:00am-1:00pm 10 2 2 3,4,5 1:00pm-4:00pm 7 3 3 3,6,7 10:00am-2:00pm 10 4 4 3,4,5,6 8:30am-12:30pm 12 5 5 3,4,5,6,7 9:00am-4:00pm 30 emp_leave id empid leavedate -------------------------------- 1 2 2012-12-05 14:42:36 2 2 2012-12-03 14:42:59 3 3 2012-12-03 14:43:06 4 3 2012-12-06 14:43:14 5 5 2012-12-04 14:43:24 My task is to find all the days in a month in which the doctor is available excluding the leave dates. My query what is wrote is given below: SELECT DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) AS Date, ROW +1 AS DayOfMonth FROM ( SELECT @row := @row +1 AS ROW FROM ( SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 )t1, ( SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 )t2, ( SELECT @row := -1 )t3 LIMIT 31 )b WHERE DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) BETWEEN '2012-12-01' AND '2012-12-31' AND DAYOFWEEK( DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) ) =2 AND DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) NOT IN ( SELECT DATE_FORMAT( l.leavedate, '%Y-%m-%d' ) AS date FROM doctors_dutyplan d LEFT JOIN emp_leave AS l ON d.doctor_id = l.empid WHERE doctor_id =2 ) This works fine for all doctors who took any leave in a particular day in a month (here in the example it is Decemeber 2012). and the result is shown below: Date DayOfMonth ----------------------- 2012-12-10 10 2012-12-17 17 2012-12-24 24 2012-12-31 31 But on the other hand for the doctors who did'nt took any leave , for that my query is showing empty table, example for the doctor Mathew whose id is 1, my query returns an empty result can anyone please tell a solution for this problem. Thanks in advance.

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• Any way to speed up this hierarchical query?

  - by RenderIn

  I've got a serious performance problem with a hierarchical query that I can't seem to fix. I am modeling several organization charts in my database, each representing a virtual organization within our company. For example, we have several temporary committees that are created from time to time and there may be a Committee Organizer role at the top of this virtual hierarchy, with several people assigned to the Committee Member role beneath the organizer. Some of our virtual organizations have many levels and several branches at each level. I have a single table in which I represent all the role assignments. i.e. a ROLE_ID column and a PARENT_ROLE_ID column which is a foreign key to the ROLE_ID column. For each assignment we also store as a column the location in the company where this person has the assignment. For example, the Committee Organizer would have a company-level/ CEO assignment, while the committee members would have department-level assignments such as ACCOUNTING, MARKETING, etc. So to model the organizer/member relationship for two individuals we would have: ROLE_ID = 4 PARENT_ROLE_ID = NULL EMPLOYEE_NUMBER = 213423 COMPANY_LOCATION = CEO ROLE_ID = 5 PARENT_ROLE_ID = 4 EMPLOYEE_NUMBER = 838221 COMPANY_LOCATION = ACCOUNTING Here's where things get tricky. I have an application that every person in the organization can log in to. When they log in they should be able to view all the virtual organizations in our company. e.g. the committee members should be able to see the committee organizer and vice-versa. However, only the committee organizer should be able to edit the committee members. The difficulty is in determining whether an individual (who can have multiple role assignments) has edit access for each other assignment. While this seems simple in the example, consider a virtual organization in which we have President at the top, 5 departments directly beneath him, 2 subdepartments below each department. We only want people in the Accounting department to be able to edit individuals in the subdepartments belonging to the Accounting department. They should not have edit access to anybody in the Marketing department or its subdepartments. To determine edit access when a user views a virtual organization in our company I run a query that executes two inline views: A) Hierarchically query for all assignments in this virtual organization and using SYS_CONNECT_BY_PATH to store the entire path to each user/role/company_location and B) Hierarchically retrieve all the assignments the individual logged in has and using the SYS_CONNECT_BY_PATH to store the entire path to each of these assignments. The result of the query is all the records from A) plus a boolean determined by joining with B) which flags whether the logged in user has edit access for each record. Indexes don't seem to be helping... it simply appears that there is too much processing going on to separate all the records and then determine edit access. One issue is that I can't store the SYS_CONNECT_BY_PATH and index it... determining whether an individual record has edit access consists of comparing if: test_record_sys_path LIKE individual_record_sys_path || '%' Is a materialized view the answer?

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• How to debug issues with differing execution times in different contexts.

  - by Dave

  The following question seems to be haunting me more consistently than most other questions recently. What kinds of things would you suggest I suggest that they look for when trying to debug "performance issues" like this? ok, get this - running this in query analyzer takes < 1 second exec usp_MyAccount_Allowance_Activity '1/1/1900', null, 187128 debugging locally, this takes 10 seconds: DataSet allowanceBalance = SqlHelper.ExecuteDataset( WebApplication.SQLConn(), CommandType.StoredProcedure, "usp_MyAccount_Allowance_Activity", Params); same parameters

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• How can I add default values to a parameterized query

  - by Sean Taylor

  When using stored procedures I am able to add default values to parameters, for example: @name varchar(50) = NULL Is is possible to do something similar when using a parameterized query in .NET. Thanks

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• Code changes in the Dtsx file in an SSIS package not reflecting after deploying and running on the server

  - by SKumar

  I have some folder called Test-Deploy in which I keep all the dtsx files, manifest and configuration files. Whenever I want to deploy the ssis package, I run manifest file in this folder and deploy. My problem is I have to change one of the dtsx files out of it. So, I opened only that particular dtsx file BI studio, updated and built. After the build, I copied the dtsx file from bin folder and copied to my Test-Deploy folder. When I deployed and run this new package in the Test-Deploy folder, the changes I made are not reflecting in the result. I could not find any difference in the results before and after changing. My doubt is has it saved my previous dtsx file somewhere on the server and executing the same dtsx file instead of the new one?

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• Compiled Queries and "Parameters cannot be sequences"

  - by David B

  I thought that compiled queries would perform the same query translation as DataContext. Yet I'm getting a run-time error when I try to use a query with a .Contains method call. Where have I gone wrong? //private member which holds a compiled query. Func<DataAccess.DataClasses1DataContext, List<int>, List<DataAccess.TestRecord>> compiledFiftyRecordQuery = System.Data.Linq.CompiledQuery.Compile <DataAccess.DataClasses1DataContext, List<int>, List<DataAccess.TestRecord>> ((dc, ids) => dc.TestRecords.Where(tr => ids.Contains(tr.ID)).ToList()); //this method calls the compiled query. public void FiftyRecordCompiledQueryByID() { List<int> IDs = GetRandomInts(50); //System.NotSupportedException //{"Parameters cannot be sequences."} List<DataAccess.TestRecord> results = compiledFiftyRecordQuery (myContext, IDs); }

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• MySQL query advice

  - by vasion

  I am lost in MySQL documentation. I have a table with votes - it has these columns id song_id user_id created I cannot find the query which will process the information and output the 10 most voted songs in a given time period. What is it?

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• select rows with column that is not null?

  - by fayer

  by default i have one column in mysql table to be NULL. i want to select some rows but only if the field value in that column is not NULL. what is the correct way of typing it? $query = "SELECT * FROM names WHERE id = '$id' AND name != NULL"; is this correct?

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• What are the types and inner workings of a query optimizer?

  - by Frank Developer

  As I understand it, most query optimizers are cost-based. Some can be influenced by hints like FIRST_ROWS(). Others are tailored for OLAP. Is it possible to know more detailed logic about how Informix IDS and SE's optimizers decide what's the best route for processing a query, other than SET EXPLAIN? Is there any documentation which illustrates the ranking of SELECT statements? I would imagine that "SELECT col FROM table WHERE ROWID = n" ranks 1st. What are the rest of them?.. If I'm not mistaking, Informix's ROWID is a SERIAL(INT) which allows for a max. of 2GB nrows, or maybe it uses INT9 for TB's nrows?.. However, I think Oracle uses HEX values for ROWID. Too bad ROWID can't be oftenly used, since a rows ROWID can change. So maybe ROWID is used by the optimizer as a counter? Perhaps, it could be used for implementing the query progress idea I mentioned in my "Begin viewing query results before query completes" question? For some reason, I feel it wouldn't be that difficult to report a query's progress while being processed, perhaps at the expense of some slight overhead, but it would be nice to know ahead of time: A "Google-like" estimate of how many rows meet a query's criteria, display it's progress every 100, 200, 500 or 1,000 rows, give users the ability to cancel it at anytime and start displaying the qualifying rows as they are being put into the current list, while it continues searching?.. This is just one example, perhaps we could think other neat/useful features, the ingridients are more or less there. Perhaps we could fine-tune each query with more granularity than currently available? OLTP queries tend to be mostly static and pre-defined. The "what-if's" are more OLAP, so let's try to add more control and intelligence to it? So, therefore, being able to more precisely control, not "hint-influence" a query is what's needed and therefore it would be necessary to know how the optimizers logic is programmed. We can then have Dynamic SELECT and other statements for specific situations! Maybe even tell IDS to read blocks of indexes nodes at-a-time instead of one-by-one, etc. etc.

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