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  • How do I introspect on a SQL Server?

    - by MetaHyperBolic
    I have a server with a vendor application which is heavily database-reliant. I need to make some minor changes to the data in a few tables in the database in an automated fashion. Just INSERTs and UPDATEs, nothing fancy. Vendors being vendors, I can never be quite sure when they change the schema of a database during upgrade. To that end, how do I ask the SQL server, in some scriptable fashion, "Hey, does this table still exist? Yeah, cool, okay, but does it have this column? What's the data type and size on that? Is it nullable? Could you give me a list of tables? In this table, could you give me a list of columns? Any primary keys there?" I do not need to do this for the whole schema, only part of it, just a quick check of the database before I launch into things. We have Microsoft SQL Server 2005 on it currently, but it might easily move to Microsoft SQL Server 2008. I am probably not using the correct terminology when searching. I do know that ORM is not only too much overhead for this sort of thing, but also that I have no chance of pitching it to my coworkers.

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  • LINQ to SQL Queries odd Materialization

    - by ptoinson
    I ran across an interesting Linq to SQL, uh, feature, the other day. Perhaps someone can give me a logical explanation for the reasoning behind the results. Take the code below as my example which utilizes the AdventureWorks database setup in a Linq to SQL DataContext. This is a clip from my unit test. The resulting customer returned from a call to both CustomerQuery_Test_01() and CustomerQuery_Test_02() is the same. However, the query executed on the SQLServer are different is a major way. The method CustomerQuery_Test_01 us causing the entire Customer table to be materialized, which the call to CustomerQuery_Test_02 is only causing the single customer to be materialized. The resulting SQL Queries are at the bottom of this post. Anyone have a good reason for this? To me, it was highly non-intuitive. protected virtual Customer GetByPrimaryKey(Func<Customer, bool> keySelection) { AdventureWorksDataContext context = new AdventureWorksDataContext(); return (from r in context.Customers select r).SingleOrDefault(keySelection); } [TestMethod] public void CustomerQuery_Test_01() { Customer customer = GetByPrimaryKey(c => c.CustomerID == 2); } [TestMethod] public void CustomerQuery_Test_02() { AdventureWorksDataContext context = new AdventureWorksDataContext(); Customer customer = (from r in context.Customers select r).SingleOrDefault(c => c.CustomerID == 2); } Query for CustomerQuery_Test_01 (notice the lack of a where clause) SELECT [t0].[CustomerID], [t0].[NameStyle], [t0].[Title], [t0].[FirstName], [t0].[MiddleName], [t0].[LastName], [t0].[Suffix], [t0].[CompanyName], [t0].[SalesPerson], [t0].[EmailAddress], [t0].[Phone], [t0].[PasswordHash], [t0].[PasswordSalt], [t0].[rowguid], [t0].[ModifiedDate] FROM [SalesLT].[Customer] AS [t0] Query for CustomerQuery_Test_02 (notice the where clause) SELECT [t0].[CustomerID], [t0].[NameStyle], [t0].[Title], [t0].[FirstName], [t0].[MiddleName], [t0].[LastName], [t0].[Suffix], [t0].[CompanyName], [t0].[SalesPerson], [t0].[EmailAddress], [t0].[Phone], [t0].[PasswordHash], [t0].[PasswordSalt], [t0].[rowguid], [t0].[ModifiedDate] FROM [SalesLT].[Customer] AS [t0] WHERE [t0].[CustomerID] = @p0

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  • Would you allow this type of query?

    - by user564577
    I'm exploring using an ORM tool in our development shop, and in particular Entity Framework 4.0. Since we work with VERY large databases, I'm a bit concerned about the query's it generates. Doing something simple like getting clients with an address in a state looks like below. As a database developer or admin would you allow this? Is it as bad as it looks? Assume every join is on a clustered index. SELECT [Project2].[ClientKey] AS [ClientKey], [Project2].[FirstName] AS [FirstName], [Project2].[LastName] AS [LastName], [Project2].[IsEnabled] AS [IsEnabled], [Project2].[ChangeUser] AS [ChangeUser], [Project2].[ChangeDate] AS [ChangeDate], [Project2].[C1] AS [C1], [Project2].[AddressKey] AS [AddressKey], [Project2].[ClientKey1] AS [ClientKey1], [Project2].[AddressTypeCode] AS [AddressTypeCode], [Project2].[PrimaryAddress] AS [PrimaryAddress], [Project2].[AddressLine1] AS [AddressLine1], [Project2].[AddressLine2] AS [AddressLine2], [Project2].[City] AS [City], [Project2].[State] AS [State], [Project2].[ZIP] AS [ZIP] FROM ( SELECT [Distinct1].[ClientKey] AS [ClientKey], [Distinct1].[FirstName] AS [FirstName], [Distinct1].[LastName] AS [LastName], [Distinct1].[IsEnabled] AS [IsEnabled], [Distinct1].[ChangeUser] AS [ChangeUser], [Distinct1].[ChangeDate] AS [ChangeDate], [Extent3].[AddressKey] AS [AddressKey], [Extent3].[ClientKey] AS [ClientKey1], [Extent3].[AddressTypeCode] AS [AddressTypeCode], [Extent3].[PrimaryAddress] AS [PrimaryAddress], [Extent3].[AddressLine1] AS [AddressLine1], [Extent3].[AddressLine2] AS [AddressLine2], [Extent3].[City] AS [City], [Extent3].[State] AS [State], [Extent3].[ZIP] AS [ZIP], CASE WHEN ([Extent3].[AddressKey] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1] FROM (SELECT DISTINCT [Extent1].[ClientKey] AS [ClientKey], [Extent1].[FirstName] AS [FirstName], [Extent1].[LastName] AS [LastName], [Extent1].[IsEnabled] AS [IsEnabled], [Extent1].[ChangeUser] AS [ChangeUser], [Extent1].[ChangeDate] AS [ChangeDate] FROM [Common].[Clients] AS [Extent1] INNER JOIN [Common].[ClientAddresses] AS [Extent2] ON [Extent1].[ClientKey] = [Extent2].[ClientKey] WHERE (( CAST(CHARINDEX(UPPER('D'), UPPER([Extent1].[LastName])) AS int)) > 0) AND ([Extent1].[IsEnabled] = 1) AND ([Extent2].[City] IS NOT NULL) AND ((UPPER([Extent2].[City])) = (UPPER('Colorado Springs'))) ) AS [Distinct1] LEFT OUTER JOIN [Common].[ClientAddresses] AS [Extent3] ON [Distinct1].[ClientKey] = [Extent3].[ClientKey] ) AS [Project2] ORDER BY [Project2].[ClientKey] ASC, [Project2].[FirstName] ASC, [Project2].[LastName] ASC, [Project2].[IsEnabled] ASC, [Project2].[ChangeUser] ASC, [Project2].[ChangeDate] ASC, [Project2].[C1] ASC

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  • How to filter rows on a complex filter

    - by dan
    I have these rows in a table ID Name Price Delivery == ==== ===== ======== 1 apple 1 1 2 apple 3 2 3 apple 6 3 4 apple 9 4 5 orange 4 6 6 orange 5 7 I want to have the price at the third delivery (Delivery=3) or the last price if there's no third delivery. It would give me this : ID Name Price Delivery == ==== ===== ======== 3 apple 6 3 6 orange 5 7 I don't necessary want a full solution but an idea of what to look for would be greatly appreciated.

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  • Hibernate Criteria API: get n random rows

    - by hadrien
    I can't figure out how to fetch n random rows from a criteria instance: Criteria criteria = session.createCriteria(Table.class); criteria.add(Restrictions.eq('fieldVariable', anyValue)); ... Then what? I can't find any doc with Criteria API Does it mean I should use HQL instead? Thanx! EDIT: I get the number of rows by: int max = criteria.setProjecxtion(Projections.rowCount()).uniqueResult(); How do I fetch n random rows with indexes between 0 and max? Thx again!

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  • Linq-to-sql join/where?

    - by Curtis White
    I've the following table structures Users id Types id isBool UsersTypes userid types I want to select all the UserTypes based on id and isBool. I tried this query var q = from usertype in usertypes from type in types where type.isBool == false where userstypes.user == id select usertype; But this did not work as expected. My questions are: Why? Is there any difference in using the join on syntax vs where, where vs where cond1 && cond2? My understanding is query optimizer will optimize. Is there any difference in using where cond1 == var1 && cond2 == var2 with and without the parenthesis? This seems peculiar that it is possible to build this without parenthesis What type of query do I need in this case? I can see that I could do a subquery or use a group but not 100% sure if it is required. An example might be helpful. I'm thinking a subquery may be required in this case.

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  • Is it possible to aggregate over differing where clauses?

    - by BenAlabaster
    Is it possible to calculate multiple aggregates based on differing where clauses? For instance: Let's say I have two tables, one for Invoice and one for InvoiceLineItems. The invoice table has a total field for the invoice total, and each of the invoice line item records in the InvoiceLineItems table contains a field that denotes whether the line item is discountable or not. I want three sum totals, one where Discountable = 0 and one where Discountable = 1 and one where Discountable is irrelevant. Such that my output would be: InvoiceNumber Total DiscountableTotal NonDiscountableTotal ------------- ----- ----------------- -------------------- 1 53.27 27.27 16.00 2 38.94 4.76 34.18 3... The only way I've found so far is by using something like: Select i.InvoiceNumber, i.Total, t0.Total As DiscountableTotal, t1.Total As NonDiscountableTotal From Invoices i Left Join ( Select InvoiceNumber, Sum(Amount), From InvoiceLineItems Where Discountable = 0 Group By InvoiceNumber ) As t0 On i.InvoiceNumber = t0.InvoiceNumber Left Join ( Select InvoiceNumber, Sum(Amount) From InvoiceLineItems Where Discountable = 1 Group By InvoiceNumber ) As t1 On i.InvoiceNumber = t1.InvoiceNumber This seems somewhat cumbersome, it would be nice if I could do something like: Select InvoiceNumber, Sum(Amount) Where Discountable = 1 As Discountable Sum(Amount) Where Discountable = 0 As NonDiscountable Group By InvoiceNumber I realize that SQL is completely invalid, but it logically portrays what I'm trying to do... TIA P.S. I need this to run on a SQL Server 2000 instance, but I am also interested (for future reference) if/how I would achieve this on SQL Server 2005/2008.

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  • Get consolidated results with following tables

    - by Ted
    I have a scenario. Here's my table structure is: ID LoginDate RemovalDate ---------------------------------------- 1 2009/08/01 NULL 2 2009/09/12 2010/01/02 3 2009/08/31 2009/10/29 4 2010/02/17 NULL 5 2009/10/18 2009/11/22 I want a consolidated results of how many ID's were not removed in a particular month. So the result set should be Date NotRemoved_ID -------------------------- 2009/08 2 2009/09 3 2009/10 3 [One ID got removed in 2009/10] 2010/02 2 [Two got removed in 2009/11 and 2010/01] Please help.

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  • Counting character count in Access database column ins SQL

    - by jzr
    Good Evening. My problem is possibly very easy, I just have spent some time researching now and probably have a brain lock and unable to solve this, help would be much appreciated. database structure: col1 col2 col3 col4 ==================== 1233+4566+ABCD+CDEF 1233+4566+ACD1+CDEF 1233+4566+D1AF+CDEF I need to count character count in col3, wanted result in from the previous table would be: char count =========== A 3 B 1 C 2 D 3 F 1 1 2 is this possible to achieve by using SQL only? at the moment I am thinking of passing a parameter in to SQL query and count the characters one by one and then sum, however I did not start the VBA part yet, and frankly wouldn't want to do that. this is my query at the moment: PARAMETERS X Long; SELECT First(Mid(TABLE.col3,X,1)) AS [col3 Field], Count(Mid(TABLE.col3,X,1)) AS Dcount FROM TEST GROUP BY Mid(TABLE.col3,X,1) HAVING (((Count(Mid([TABLE].[col3],[X],1)))>=1)); ideas and help are much appreciated, as being said this is probably very for some of your guys, I don't usually work with access and SQL. Thanks.

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  • MySQL - Limit a left join to the first date-time that occurs?

    - by John M
    Simplified table structure (the tables can't be merged at this time): TableA: dts_received (datetime) dts_completed (datetime) task_a (varchar) TableB: dts_started (datetime) task_b (varchar) What I would like to do is determine how long a task took to complete. The join parameter would be something like ON task_a = task_b AND dts_completed < dts_started The issue is that there may be multiple date-times that occur after the dts_completed. How do I create a join that only returns the first tableB-datetime that occurs after the tableA-datetime?

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  • Dynamic SQL and Funtions

    - by Unlimited071
    Hi all, is there any way of accomplishing something like the following: CREATE FUNCTION GetQtyFromID ( @oricod varchar(15), @ccocod varchar(15), @ocmnum int, @oinnum int, @acmnum int, @acttip char(2), @unisim varchar(15) ) AS BEGIN DECLARE @Result decimal(18,8) DECLARE @SQLString nvarchar(max); DECLARE @ParmDefinition nvarchar(max); --I need to execute a query stored in a cell which returns the calculated qty. --i.e of AcuQry: select @cant = sum(smt) from table where oricod = @oricod and ... SELECT @SQLString = AcuQry FROM OinActUni WHERE (OriCod = @oricod) AND (ActTipCod = @acttip) AND (UniSim = @unisim) AND (AcuEst > 0) SET @ParmDefinition = N' @oricod varchar(15), @ccocod varchar(15), @ocmnum int, @oinnum int, @acmnum int, @cant decimal(18,8) output'; EXECUTE sp_executesql @SQLString, @ParmDefinition, @oricod = @oricod, @ccocod = @ccocod, @ocmnum = @ocmnum, @oinnum = @oinnum, @acmnum = @acmnum, @cant = @result OUTPUT; RETURN @Result END The problem with this approach is that it is prohibited to execute sp_excutesql in a function... What I need is to do something like: select id, getQtyFromID(id) as qty from table The main idea is to execute a query stored in a table cell, this is because the qty of something depends on it's unit. the unit can be days or it can be metric tons, so there is no relation between the units, therefore the need of a specific query for each unit.

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  • When to use CTEs to encapsulate sub-results, and when to let the RDBMS worry about massive joins.

    - by IanC
    This is a SQL theory question. I can provide an example, but I don't think it's needed to make my point. Anyone experienced with SQL will immediately know what I'm talking about. Usually we use joins to minimize the number of records due to matching the left and right rows. However, under certain conditions, joining tables cause a multiplication of results where the result is all permutations of the left and right records. I have a database which has 3 or 4 such joins. This turns what would be a few records into a multitude. My concern is that the tables will be large in production, so the number of these joined rows will be immense. Further, heavy math is performed on each row, and the idea of performing math on duplicate rows is enough to make anyone shudder. I have two questions. The first is, is this something I should care about, or will SQL Server intelligently realize these rows are all duplicates and optimize all processing accordingly? The second is, is there any advantage to grouping each part of the query so as to get only the distinct values going into the next part of the query, using something like: WITH t1 AS ( SELECT DISTINCT... [or GROUP BY] ), t2 AS ( SELECT DISTINCT... ), t3 AS ( SELECT DISTINCT... ) SELECT... I have often seen the use of DISTINCT applied to subqueries. There is obviously a reason for doing this. However, I'm talking about something a little different and perhaps more subtle and tricky.

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  • LinqtoSql Pre-compile Query problem with Count() on a group by

    - by Joe Pitz
    Have a LinqtoSql query that I now want to precompile. var unorderedc = from insp in sq.Inspections where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime && insp.Model == "EP" && insp.TestResults != "P" group insp by new { insp.TestResults, insp.FailStep } into grp select new { FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0), CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0), grp.Key.TestResults, grp.Key.FailStep, PercentFailed = Convert.ToDecimal(1.0 * grp.Count() / tcount * 100) }; I have created this delegate: public static readonly Funct<SQLDataDataContext, int, string, string, DateTime, DateTime, IQueryable<CalcFailedTestResult>> GetInspData = CompiledQuery.Compile((SQLDataDataContext sq, int tcount, string strModel, string strTest, DateTime dStartTime, DateTime dEndTime, IQueryable<CalcFailedTestResult> CalcFailed) => from insp in sq.Inspections where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime && insp.Model == strModel && insp.TestResults != strTest group insp by new { insp.TestResults, insp.FailStep } into grp select new { FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0), CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0), grp.Key.TestResults, grp.Key.FailStep, PercentFailed = Convert.ToDecimal(1.0 * grp.Count() / tcount * 100) }); The syntax error is on the CompileQuery.Compile() statement It appears to be related to the use of the select new {} syntax. In other pre-compiled queries I have written I have had to just use the select projection by it self. In this case I need to perform the grp.count() and the immediate if logic. I have searched SO and other references but cannot find the answer.

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  • Access to SQL Server 2005 from a non-domain machine using Windows authentication

    - by user304582
    Hi, I have a Windows domain within which a machine is running SQL Server 2005 and which is configured to support only Windows authentication. I would like to run a C# client application on a machine on the same network, but which is NOT on the domain, and access a database on the SQL Server 2005 instance. I thought that it would be a simple matter of doing something like this: string connectionString = "Data Source=server;Initial Catalog=database;User Id=domain\user;Password=password"; SqlConnection connection = new SqlConnection(connectionString); connection.Open(); However, this fails: the client-side error is: System.Data.SqlClient.SqlException: Login failed for user 'domain\user' and the server-side error is: Error 18456, Severity 14, State 5 I have tried various things including setting integrated security to true and false, and \ instead of \ in the User Id, but without success. In general, I know that it possible to connect to the SQL Server 2005 instance from a non-domain machine (for example, I am working with a Linux-based application which happily does this), but I don't seem to be able to work out how to do it from a Windows machine. Help would be appreciated! Thanks, Martin

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  • mysql count(*) left join group by - the number of files in a folder

    - by Flavius
    Hi I have the following tables CREATE TABLE `files` ( `fileid` int(11) NOT NULL AUTO_INCREMENT, `filename` varchar(255) NOT NULL, `filesize` int(11) NOT NULL, `folder` int(11) NOT NULL, PRIMARY KEY (`fileid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE `folders` ( `directoryid` int(11) NOT NULL AUTO_INCREMENT, `directoryname` varchar(255) NOT NULL, PRIMARY KEY (`directoryid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; How to get a list of all folders and the number of files they hold, including folders who have no (zero) files? Recursion must not be taken into account. Found it select folders.directoryid, folders.directoryname, count(files.fileid) as no_files from folders left join files on files.folder = folders.directoryid group by folders.directoryid, folders.directoryname I hope it will help someone.

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  • Select Query Joined on Two Fields?

    - by btollett
    I've got a few tables in an access database: ID | LocationName 1 | Location1 2 | Location2 ID | LocationID | Date | NumProductsDelivered 1 | 1 | 12/10 | 3 2 | 1 | 01/11 | 2 3 | 1 | 02/11 | 2 4 | 2 | 11/10 | 1 5 | 2 | 12/10 | 1 ID | LocationID | Date | NumEmployees | EmployeeType 1 | 1 | 12/10 | 10 | 1 (=Permanent) 2 | 1 | 12/10 | 3 | 2 (=Temporary) 3 | 1 | 12/10 | 1 | 3 (=Support) 4 | 2 | 10/10 | 1 | 1 5 | 2 | 11/10 | 2 | 1 6 | 2 | 11/10 | 1 | 2 7 | 2 | 11/10 | 1 | 3 8 | 2 | 12/10 | 2 | 1 9 | 2 | 12/10 | 1 | 3 What I want to do is pass in the LocationID as a parameter and get back something like the following table. So, if I pass in 2 as my LocationID, I should get: Date | NumProductsDelivered | NumPermanentEmployees | NumSupportEmployees 10/10 | | 1 | 11/10 | 1 | 2 | 1 12/10 | 1 | 2 | 1 It seems like this should be a pretty simple query. I really don't even need the first table except as a way to fill in the combo box on the form from which the user chooses which location they want a report for. Unfortunately, everything I've done has resulted in me getting a lot more data than I should be getting. My confusion is in how to set up the join (presumably that's what I'm looking for here) given that I want both the date and locationID to be the same for each row in the result set. Any help would be much appreciated. Thanks.

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  • wanted to get all dates in mysql result

    - by PankajK
    I have mysql table called user(id, name, join_on) join on is a date field what I want is to show in each day how many uses has been created I can use group by but it will only give me the dates when users get added like if date 4/12/10 5 users added 4/13/10 2 users added 4/15/10 7 users added here date 4/14/10 is missing and I want listing of all dates in one month. I have one solution for it by creating another table only for adding date and that table will left join my users table on join_on and will give total result but I don't want to do that as for creating that I need to create and add entries in date table please suggest the different approach for doing so. Thank you.

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  • Google App Engine query data store by a string start with ...

    - by Frank
    How to write a query that can find me all item_number start with a certain value ? For instance there are item_numbers like these : 123_abc 123_xyz ierireire 321_add 999_pop My current query looks like this : "select from "+PayPal_Message.class.getName()+" where item_number == '"+Item_Number+"' order by item_number desc" What's a query look like that can return all item_numbers start with "123_" ?

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  • SQL Server 2008, Books Online, and old documentation...

    - by Chris J
    [I have no idea if stackoverflow really is right right place for this, but don't know how many devs on here run into msi issues with SQL Server; suggest SuperUser or ServerFault if folk think it's better on either of those] About a year ago, when we were looking at moving our codebase forward and migrating to SQL Server 2008, I pulled down a copy of Books Online from the MSDN. Reviewed, did background research, fed results upstream, grabbed Express and tinkered with that. Then we got the nod to move forward (hurrah!) this past couple of weeks. So armed with Developer Edition, and running through the install, I've since found out I've zapped the Books Online MSI, no-ones got a copy of it, and Microsoft only have a later version (Oct 2009) available, so damned if I can update my SQL Server fully and properly... {mutter grumble}. Does anyone know if old versions of Books Online are available for download anywhere? Poking around the Microsoft download centre can't find it, neither is my google-fu finding it. For reference, I'm looking for SQLServer2008_BOL_August2008_ENU.msi ... This may just be a case of good ol' manual delete the files and (try) and clean up the registry :-(

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  • Joining tables, if percentage is above certain value

    - by CluelessGerman
    My question is similar to this one: Compare rows and get percentage However, little different. I adapted my question to the other post. I got 2 tables. First table: user_id | post_id 1 1 1 2 1 3 2 12 2 15 And second table: post_id | rating 1 1 1 2 1 3 2 1 2 5 3 null 3 1 3 4 12 4 15 1 So now I would like to count the rating for each post, in the second table. If the rating has more than, lets say, 50% positive ratings than I want to get the post_id and going it to the post_id from table one and add 1 to the user_id. At the end it would return the user_id with the number of positive posts. The result for above table would be: user_id | helpfulPosts 1 2 2 1 The post with post_id 1 and 3 have positive rating, because more than 50% have ratings of 1-3. The post with id = 2 is not positive, because the rating is exactly 50%. How would I achieve this? For clarification: It's a mysql rdbm and a positive post, is one where the number of rating_ids with 1, 2 and 3 are more than half of the overall rating. Basically the same thing, from the other thread I posted above.

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  • Query table value aliasing in Oracle SQL

    - by Strata
    I have a homework assignment in SQL for Oracle 10g where I have to apply union to two different select statements, to return two columns. I need the values of each cell under vendor_state to indicate CA and every other value in another state to return "Outside CA", to indicate they're elsewhere. I applied the union and produced the two columns and the listings for CA, but many other state IDs were listed and I couldn't find an explanation for how to change the actual values in the query itself. Eventually, I stumbled on an answer, but I can't explain why this works. The code is as follows: SELECT vendor_name, vendor_state FROM vendors WHERE vendor_state IN 'CA' UNION SELECT vendor_name, 'Outside CA' AS vendor_state FROM vendors WHERE vendor_state NOT IN 'CA' ORDER BY vendor_name This gives me the exact answer I need, but I don't know why the aliasing in the second select statement can behave this way....no explanation is given in my textbook and nothing I've read indicates that column aliasing can be done like this. But, by switching the column name and the alias value, I have replaced the value being returned rather than the column name itself...I'm not complaining about the result, but it would help if I knew how I did it.

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  • multiple mysql_real_query() in while loop

    - by Steve
    It seems that when I have one mysql_real_query() function in a continuous while loop, the query will get executed OK. However, if multiple mysql_real_query() are inside the while loop, one right after the other. Depending on the query, sometimes neither the first query nor second query will execute properly. This seems like a threading issue to me. I'm wondering if the mysql c api has a way of dealing with this? Does anyone know how to deal with this? mysql_free_result() doesn't work since I am not even storing the results. //keep polling as long as stop character '-' is not read while(szRxChar != '-') { // Check if a read is outstanding if (HasOverlappedIoCompleted(&ovRead)) { // Issue a serial port read if (!ReadFile(hSerial,&szRxChar,1, &dwBytesRead,&ovRead)) { DWORD dwErr = GetLastError(); if (dwErr!=ERROR_IO_PENDING) return dwErr; } } // Wait 5 seconds for serial input if (!(HasOverlappedIoCompleted(&ovRead))) { WaitForSingleObject(hReadEvent,RESET_TIME); } // Check if serial input has arrived if (GetOverlappedResult(hSerial,&ovRead, &dwBytesRead,FALSE)) { // Wait for the write GetOverlappedResult(hSerial,&ovWrite, &dwBytesWritten,TRUE); //load tagBuffer with byte stream tagBuffer[i] = szRxChar; i++; tagBuffer[i] = 0; //char arrays are \0 terminated //run query with tagBuffer if( strlen(tagBuffer)==PACKET_LENGTH ) { sprintf(query,"insert into scan (rfidnum) values ('"); strcat(query, tagBuffer); strcat(query, "')"); mysql_real_query(&mysql,query,(unsigned int)strlen(query)); i=0; } mysql_real_query(&mysql,"insert into scan (rfidnum) values ('2nd query')",(unsigned int)strlen("insert into scan (rfid) values ('2nd query')")); mysql_free_result(res); } }

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