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  • mysql query for getting all messages that belong to user's contacts

    - by aharon
    So I have a database that is setup sort of like this (simplified, and in terms of the tables, all are InnoDBs): Users: contains based user authentication information (uid, username, encrypted password, et cetera) Contacts: contains two rows per relationship that exists between users as (uid1, uid2), (uid2, uid1) to allow for a good 1:1 relationship (must be mutual) between users Messages: has messages that consist of a blob, owner-id, message-id (auto_increment) So my question is, what's the best MySQL query to get all messages that belong to all the contacts of a specific user? Is there an efficient way to do this?

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  • TSQL: finding unique entries in a single table

    - by pcampbell
    Consider a table or CTE structured like this: Name Num ---- ---- Abc 12 Abc 12 XYZ 70 XYZ 80 Bar 50 Bar 55 Foo 44 Foo 44 Baz 88 The requirement is to determine the Name where multiple different Nums exist. The desired resultset is Name ---- XYZ Bar What TSQL statement would you use to derive this resultset?

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  • Linq2SQL vs NHibernate performance (have I gone mad?)

    - by HeavyWave
    I have written the following tests to compare performance of Linq2SQL and NHibernate and I find results to be somewhat strange. Mappings are straight forward and identical for both. Both are running against a live DB. Although I'm not deleting Campaigns in case of Linq, but that shouldn't affect performance by more than 10 ms. Linq: [Test] public void Test1000ReadsWritesToAgentStateLinqPrecompiled() { Stopwatch sw = new Stopwatch(); Stopwatch swIn = new Stopwatch(); sw.Start(); for (int i = 0; i < 1000; i++) { swIn.Reset(); swIn.Start(); ReadWriteAndDeleteAgentStateWithLinqPrecompiled(); swIn.Stop(); Console.WriteLine("Run ReadWriteAndDeleteAgentState: " + swIn.ElapsedMilliseconds + " ms"); } sw.Stop(); Console.WriteLine("Total Time: " + sw.ElapsedMilliseconds + " ms"); Console.WriteLine("Average time to execute queries: " + sw.ElapsedMilliseconds / 1000 + " ms"); } private static readonly Func<AgentDesktop3DataContext, int, EntityModel.CampaignDetail> GetCampaignById = CompiledQuery.Compile<AgentDesktop3DataContext, int, EntityModel.CampaignDetail>( (ctx, sessionId) => (from cd in ctx.CampaignDetails join a in ctx.AgentCampaigns on cd.CampaignDetailId equals a.CampaignDetailId where a.AgentStateId == sessionId select cd).FirstOrDefault()); private void ReadWriteAndDeleteAgentStateWithLinqPrecompiled() { int id = 0; using (var ctx = new AgentDesktop3DataContext()) { EntityModel.AgentState agentState = new EntityModel.AgentState(); var campaign = new EntityModel.CampaignDetail { CampaignName = "Test" }; var campaignDisposition = new EntityModel.CampaignDisposition { Code = "123" }; campaignDisposition.Description = "abc"; campaign.CampaignDispositions.Add(campaignDisposition); agentState.CallState = 3; campaign.AgentCampaigns.Add(new AgentCampaign { AgentState = agentState }); ctx.CampaignDetails.InsertOnSubmit(campaign); ctx.AgentStates.InsertOnSubmit(agentState); ctx.SubmitChanges(); id = agentState.AgentStateId; } using (var ctx = new AgentDesktop3DataContext()) { var dbAgentState = ctx.GetAgentStateById(id); Assert.IsNotNull(dbAgentState); Assert.AreEqual(dbAgentState.CallState, 3); var campaignDetails = GetCampaignById(ctx, id); Assert.AreEqual(campaignDetails.CampaignDispositions[0].Description, "abc"); } using (var ctx = new AgentDesktop3DataContext()) { ctx.DeleteSessionById(id); } } NHibernate (the loop is the same): private void ReadWriteAndDeleteAgentState() { var id = WriteAgentState().Id; StartNewTransaction(); var dbAgentState = agentStateRepository.Get(id); Assert.IsNotNull(dbAgentState); Assert.AreEqual(dbAgentState.CallState, 3); Assert.AreEqual(dbAgentState.Campaigns[0].Dispositions[0].Description, "abc"); var campaignId = dbAgentState.Campaigns[0].Id; agentStateRepository.Delete(dbAgentState); NHibernateSession.Current.Transaction.Commit(); Cleanup(campaignId); NHibernateSession.Current.BeginTransaction(); } Results: NHibernate: Total Time: 9469 ms Average time to execute 13 queries: 9 ms Linq: Total Time: 127200 ms Average time to execute 13 queries: 127 ms Linq lost by 13.5 times! Event with precompiled queries (both read queries are precompiled). This can't be right, although I expected NHibernate to be faster, this is just too big of a difference, considering mappings are identical and NHibernate actually executes more queries against the DB.

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  • What are the disadvantages of VistaDB

    - by PhantomTypist
    I am looking into using a lightweight serverless database engine like SQLite, Firebird, or VistaDB in an upcoming project. Someone asked about What are the advantages of VistaDB. I would like to know what are the disadvantages of using VistaDB versus other technology?

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  • How do views reduce code duplication?

    - by Debuger
    Hi! I read something like this about db views: Views are incredibly powerful and useful for one reason that stands out above all the other very good reasons. They reduce code duplication. That is, in most cases, the bottom line. If a query will be used in three or more places, then a view will drastically simplify your changes if the schema or query parameters change. I once had to edit 22 stored procedures to change some query logic. If the original architecture had utilized views, then I would have had only three changes. Can anyone explain to me how it works, and maybe give me some examples? Best regards!

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  • Mysql stored procedure where clause

    - by Mneva skoko
    I am having a problem with this stored procedure: Delimiter // Create procedure(in varchar(50)) Begin Select * from employees where email = eml; End// Delimiter ; I don't get errors when I run this procedure but when i call it in my php script it returns nothing.

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  • Round date to fiscal year

    - by Dave Jarvis
    The following database view rounds the date back to the closest fiscal year (April 1st): CREATE OR REPLACE VIEW FISCAL_YEAR_VW AS SELECT CASE WHEN to_number(to_char( SYSDATE, 'MM' )) < 4 THEN to_date('1-APR-'||to_char(add_months(SYSDATE, -12), 'YYYY'), 'dd-MON-yyyy') ELSE to_date('1-APR-'||to_char(SYSDATE, 'YYYY'), 'dd-MON-yyyy') END AS fiscal_year FROM dual; This allows us to calculate the current fiscal year based on today's date. How can this calculation be simplified or optimized?

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  • Loop Control within a DataflowTask in ETL

    - by Ben
    Hi, Being fairly new to SSIS and the ETL process, I was wondering if there is anyway to loop though a record set within a DataFlowTask and pass each row (deriving parameters from the row) into a Stored Procedure (the next step in the ETL phase). Once i have passed the row into the stored procedure, I want the results from each iteration to be written to a Table. Does anyone know how to do this? Thanks.

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  • Merging sql queries to get different results by date

    - by pedalpete
    I am trying to build a 'recent events' feed and can't seem to get either my query correct, or figure out how to possible merge the results from two queries to sort them by date. One table holds games/, and another table holds the actions of these games/. I am trying to get the recent events to show users 1) the actions taken on games that are publicly visible (published) 2) when a new game is created and published. So, my actions table has actionId, gameid, userid, actiontype, lastupdate My games table has gameid, startDate, createdby, published, lastupdate I currently have a query like this (simplified for easy understanding I hope). SELECT actionId, actions.gameid, userid, actiontype, actions.lastupdate FROM actions JOIN ( SELECT games.gameid, startDate, createdby, published, games.lastupdate FROM games WHERE published=1 AND lastupdate>today-2 ) publishedGames on actions.gameid=games.gameid WHERE actions.type IN (0,4,5,6,7) AND actions.lastupdate>games.lastupdate and published=1 OR games.lastupdate>today-2 AND published=1 This query is looking for actions from published games where the action took place after the game was published. That pretty much takes care of the first thing that needs to be shown. However, I also need to get the results of the SELECT games.gameid, startDate, createdby, published, games.lastupdate FROM games WHERE published=1 AND startDate>today-2 so I can include in the actions list, when a new game has been published. When I run the query as I've got it written, I get all the actionids, and their gameids, but I don't get a row which shows the gameid when it was published. I understand that it may be possible that I need to run two seperate queries, and then somehow merge the results afterword with php, but I'm completely lost on where to start with that as well.

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  • DataContext Refresh and PropertyChanging & PropertyChanged Events

    - by Scott
    I'm in a situation where I am being informed from an outside source that a particular entity has been altered outside my current datacontext. I'm able to find the entity and call refresh like so MyDataContext.Refresh(RefreshMode.OverwriteCurrentValues, myEntity); and the properties which have been altered on the entity are updated correctly. However neither of the INotifyPropertyChanging INotifyPropertyChanged appear to be raised when the refresh occurs and this leaves my UI displaying incorrect information. I'm aware that Refresh() fails to use the correct property getters and setters on the entity to raise the change notification events, but perhaps there is another way to accomplish the same thing? Am I doing something wrong? Is there a better method than Refresh? If Refresh is the only option, does anyone have a work around?

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  • Can't find which row is causing conversion error

    - by Marwan
    I have the following table: CREATE TABLE [dbo].[Accounts1]( [AccountId] [nvarchar](50) NULL, [ExpiryDate] [nvarchar](50) NULL ) I am trying to convert nvarchar to datetime using this query: select convert(datetime, expirydate) from accounts I get this error: Conversion failed when converting datetime from character string. The status bar says "2390 rows". I go to rows 2390, 2391 and 2392. There is nothing wrong with the data there. I even try to convert those particular rows and it works. How can I find out which row(s) is causing the conversion error?

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  • add row to a BindingSource gives different autoincrement value from whats saved into DB

    - by Ruben Trancoso
    I have a DataGridView that shows list of records and when I hit a insert button, a form should add a new record, edit its values and save it. I have a BindingSource bound to a DataGridView. I pass is as a parameter to a NEW RECORD form so // When the form opens it add a new row and de DataGridView display this new record at this time DataRowView currentRow; currentRow = (DataRowView) myBindindSource.AddNew(); when user confirm to save it I do a myBindindSource.EndEdit(); // inside the form and after the form is disposed the new row is saved and the bindingsorce position is updated to the new row DataRowView drv = myForm.CurrentRow; avaliadoTableAdapter.Update(drv.Row); avaliadoBindingSource.Position = avaliadoBindingSource.Find("ID", drv.Row.ItemArray[0]); The problem is that this table has a AUTOINCREMENT field and the value saved may not correspond the the value the bindingSource gives in EDIT TIME. So, when I close and open the DataGridView again the new rowd give its ID based on the available slot in the undelying DB at the momment is was saved and it just ignores the value the BindingSource generated ad EDIT TIME, Since the value given by the binding source should be used by another table as a foreingKey it make the reference insconsistent. There's a way to get the real ID was saved to the database?

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  • ORA-01722: invalid number

    - by Lluis Martinez
    I'm getting the infamous invalid number Oracle error. Hibernate is issuing an INSERT with a lot of columns, I want to know just the name of the column giving the problem. Is it possible? I hate Oracle messages, in 15 years they haven't improved a bit (the reason why is beyond my imagination). FYI the insert is this: insert into GEM_INVOICE_HEADER (ENDORSEE_ACCOUNT_ID, INVOICE_CODE, APPROVAL_ORGAN, APROVAL_DATE, APROVAL_REFERENCE, BALANCE_BASE_AMOUNT, BALANCE_DEDUCT_AMOUNT, BALANCE_TOTAL_AMOUNT, BALANCE_VAT_AMOUNT, BALANCE_VAT_DED_AMOUNT, BALANCE_VAT_NOT_DED_AMOUNT, DESCRIPTION, SUPPLIER_INVOICE_NUMBER, INVOICE_DATE, RECEIPT_DATE, MEMO, VAT_INTRACOM, INVOICE_BASE_AMOUNT, INVOICE_VAT_AMOUNT, INVOICE_VAT_DED_AMOUNT, INVOICE_VAT_NOT_DED_AMOUNT, INVOICE_DEDUCT_AMOUNT, INVOICE_TOTAL_AMOUNT, VAT_EXEMPT, RECTIFICATION_SIGN, REASON, LOT, FILE_ID, RETAINED, INSTITUTION_ID, PERIOD_CODE, IS_RECTIFIED, DEFAULT_OFFBUDGET_ACCOUNT, OFFBUDGET_DOC_ID, PHASE_OF_ACCOUNTING, ACCOUNTED_OFF_BUDGET, CANCEL_DOC_ID, BUDGET_TYPE, INVOICE_TYPE, SOURCE_ID, STATE_ID, MANAGER_UNIT_ID, DOCUMENT_TYPE_CODE, ACCOUNTED_DOC_ID, ACCOUNTING_LIST, ENDORSEE_ID, PAYMASTER_ID, SUPPLIER_ID, SUPPLIER_ACCOUNT_ID, PAY_JUSTIFY_ID, PETTY_CASH_ID, DBOID) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)

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  • How to efficiently SELECT rows from database table based on selected set of values

    - by Chau Chee Yang
    I have a transaction table of 1 million rows. The table has a field name "Code" to keep customer's ID. There are about 10,000 different customer code. I have an GUI interface allow user to render a report from transaction table. User may select arbitrary number of customers for rendering. I use IN operator first and it works for few customers: SELECT * FROM TRANS_TABLE WHERE CODE IN ('...', '...', '...') I quickly run into problem if I select few thousand customers. There is limitation using IN operator. An alternate way is create a temporary table with only one field of CODE, and inject selected customer codes into the temporary table using INSERT statement. I may then using SELECT A.* FROM TRANS_TABLE A INNER JOIN TEMP B ON (A.CODE=B.CODE) This works nice for huge selection. However, there is performance overhead for temporary table creation, INSERT injection and dropping of temporary table. Do you aware of better solution to handle this situation?

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  • Queries with Multiple Constraints

    - by ANITHA
    I have the following tables and fields: +------------------+ +-------------------+ +---------------+ | Request | | RequestItem | | Item | +------------------+ +-------------------+ +---------------+ | + Requester_Name | | + Request_No | | + Item | +------------------+ +-------------------+ +---------------+ | + Request_No | | + Item | +------------------+ +-------------------+ I would like to filter the items which are selected under a particular request number, along with a specific requester name. How might I go about doing this?

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  • Spaced repetition (SRS) for learning

    - by Fredrik Johansson
    A client has asked me to add a simple spaced repeition algorithm (SRS) for an onlinebased learning site. But before throwing my self into it, I'd like to discuss it with the community. Basically the site asks the user a bunch of questions (by automatically selecting say 10 out of 100 total questions from a database), and the user gives either a correct or incorrect answer. The users result are then stored in a database, for instance: userid questionid correctlyanswered dateanswered 1 123 0 (no) 2010-01-01 10:00 1 124 1 (yes) 2010-01-01 11:00 1 125 1 (yes) 2010-01-01 12:00 Now, to maximize a users ability to learn all answers, I should be able to apply an SRS algorithm so that a user, next time he takes the quiz, receives questions incorrectly answered more often; than questions answered correctly. Also, questions that are previously answered incorrectly, but recently often answered correctly should occur less often. Have anyone implemented something like this before? Any tips or suggestions? Theese are the best links I've found: http://en.wikipedia.org/wiki/Spaced_repetition http://www.mnemosyne-proj.org/principles.php http://www.supermemo.com/english/ol/sm2.htm

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  • Odd GROUP BY output DB2 - Results not as expected

    - by CallCthulhu
    If I run the following query: select load_cyc_num , crnt_dnlq_age_cde , sum(cc_min_pymt_amt) as min_pymt , sum(ec_tot_bal) as budget , case when ec_tot_bal 0 then 'Y' else 'N' end as budget , case when ac_stat_cde in ('A0P','A1P','ARP','A3P') then 'Y' else 'N' end as arngmnt , sum(sn_close_bal) as st_bal from statements where (sn_close_bal 0 or ec_tot_bal 0) and load_cyc_num in (200911) group by load_cyc_num , crnt_dnlq_age_cde , case when ec_tot_bal 0 then 'Y' else 'N' end , case when ac_stat_cde in ('A0P','A1P','ARP','A3P') then 'Y' else 'N' end then I get the correct "BUDGET" grouping, but not the correct "ARRANGEMENT" grouping, only two rows have a "Y". If I change the order of the case statements in the GROUP BY, then I get the correct grouping (full Y-N breakdown for both columns). Am I missing something obvious?

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  • mysql result set joining existing table

    - by Yang
    is there any way to avoid using tmp table? I am using a query with aggregate function (sum) to generate the sum of each product: the result looks like this: product_name | sum(qty) product_1 | 100 product_2 | 200 product_5 | 300 now i want to join the above result to another table called products. so that i will have a summary like this: product_name | sum(qty) product_1 | 100 product_2 | 200 product_3 | 0 product_4 | 0 product_5 | 300 i know 1 way of doing this is the dump the 1st query result to a temp table then join it with products table. is there a better way?

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  • Using PHP variables inside SQL statements?

    - by Homer
    For some reason I can't pass a var inside a mysql statement. I have a function that can be used for multiple tables. So instead of repeating the code I want to change the table that is selected from like so, function show_all_records($table_name) { mysql_query("SELECT * FROM $table_name"); etc, etc... } And to call the function I use show_all_records("some_table") or show_all_records("some_other_table") depending on which table I want to select from at the moment. But it's not working, is this because variables can't be passed through mysql statements?

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  • Can I serialize an object if I didn't write the class used to instantiate that object?

    - by Richard77
    Hello, I've a simple class [Serializable] public class MyClass { public String FirstName { get; set: } public String LastName { get; set: } //Bellow is what I would like to do //But, it's not working //I get an exception ContactDataContext db = new ContactDataContext(); public void Save() { Contact contact = new Contact(); contact.FirstName = FirstName; contact.LastName = LastName; db.Contacts.InsertOnSubmit(contact); db.SubmitChanges(); } } I wanted to attach a Save method to the class so that I could call it on each object. When I introduced the above statement which contains ContactDataContext, I got the following error "In assembly ... PublicKeyToken=null' is not marked as serializable" It's clear that the DataContext class is generated by the framework (). I checked and did not see where that class was marked serialize. What can I do to overcome that? What's the rule when I'm not the author of a class? Just go ahead and mark the DataContext class as serializable, and pretend that everything will work? Thanks for helping

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  • PostgreSQL - fetch the row which has the Max value for a column

    - by Joshua Berry
    I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id There are multiple users (distinct usr_id's) time_stamp is not a unique identifier: sometimes user events (one by row in the table) will occur with the same time_stamp. trans_id is unique only for very small time ranges: over time it repeats remaining_lives (for a given user) can both increase and decrease over time example: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 07:00 | 1 | 1 | 1 09:00 | 4 | 2 | 2 10:00 | 2 | 3 | 3 10:00 | 1 | 2 | 4 11:00 | 4 | 1 | 5 11:00 | 3 | 1 | 6 13:00 | 3 | 3 | 1 As I will need to access other columns of the row with the latest data for each given usr_id, I need a query that gives a result like this: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 11:00 | 3 | 1 | 6 10:00 | 1 | 2 | 4 13:00 | 3 | 3 | 1 As mentioned, each usr_id can gain or lose lives, and sometimes these timestamped events occur so close together that they have the same timestamp! Therefore this query won't work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp) AS max_timestamp FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp = b.time_stamp Instead, I need to use both time_stamp (first) and trans_id (second) to identify the correct row. I also then need to pass that information from the subquery to the main query that will provide the data for the other columns of the appropriate rows. This is the hacked up query that I've gotten to work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp || '*' || trans_id) AS max_timestamp_transid FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp_transid = b.time_stamp || '*' || b.trans_id ORDER BY b.usr_id Okay, so this works, but I don't like it. It requires a query within a query, a self join, and it seems to me that it could be much simpler by grabbing the row that MAX found to have the largest timestamp and trans_id. The table "lives" has tens of millions of rows to parse, so I'd like this query to be as fast and efficient as possible. I'm new to RDBM and Postgres in particular, so I know that I need to make effective use of the proper indexes. I'm a bit lost on how to optimize. I found a similar discussion here. Can I perform some type of Postgres equivalent to an Oracle analytic function? Any advice on accessing related column information used by an aggregate function (like MAX), creating indexes, and creating better queries would be much appreciated! P.S. You can use the following to create my example case: create TABLE lives (time_stamp timestamp, lives_remaining integer, usr_id integer, trans_id integer); insert into lives values ('2000-01-01 07:00', 1, 1, 1); insert into lives values ('2000-01-01 09:00', 4, 2, 2); insert into lives values ('2000-01-01 10:00', 2, 3, 3); insert into lives values ('2000-01-01 10:00', 1, 2, 4); insert into lives values ('2000-01-01 11:00', 4, 1, 5); insert into lives values ('2000-01-01 11:00', 3, 1, 6); insert into lives values ('2000-01-01 13:00', 3, 3, 1);

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  • Should I commit or rollback a transaction that creates a temp table, reads, then deletes it?

    - by Triynko
    To select information related to a list of hundreds of IDs... rather than make a huge select statement, I create temp table, insert the ids into it, join it with a table to select the rows matching the IDs, then delete the temp table. So this is essentially a read operation, with no permanent changes made to any persistent database tables. I do this in a transaction, to ensure the temp table is deleted when I'm finished. My question is... what happens when I commit such a transaction vs. let it roll it back? Performance-wise... does the DB engine have to do more work to roll back the transaction vs committing it? Is there even a difference since the only modifications are done to a temp table? Related question here, but doesn't answer my specific case involving temp tables: http://stackoverflow.com/questions/309834/should-i-commit-or-rollback-a-read-transaction

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  • Understand Sql Server connectionstring for asp.net

    - by Eatdoku
    Hi, I am trying to understand the differences between the following 2 connectionstrings. one uses servername\instancename and the other one uses the server ip address. Can I specify port number for "serverName\instanceName". I know you can specify port number for ip address, something like '10.0.0.1,xxx'. thanks, Server=myServerName\theInstanceName;Database=myDataBase;Trusted_Connection=True; Server=myServerAddress;Database=myDataBase;Trusted_Connection=True;

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