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  • Mass data store with SQL SERVER

    - by Leo
    We need management 10,000 GPS devices, each GPS device upload a GPS data every 30 seconds, these data need to store in the database(MS SQL Server 2005). Each GPS device daily data quantity is: 24 * 60 * 2 = 2,880 10 000 10,000 GPS devices daily data quantity is: 10000 * 2880 = 28,800,000 Each GPS data approximately 160Byte, the amount of data per day is: 28,800,000 * 160 = 4.29GB We need hold at least 3 months of GPS data in the database, My question is: 1, whether SQL Server 2005 can support such a large amount of data store? 2, How to plan data table? (all GPS data storage in one table? Daily table? Each GPS device with a GPS data table?) The GPS data: GPSID varchar(21), RecvTime datetime, GPSTime datetime, IsValid bit, IsNavi bit, Lng float, Lat float, Alt float, Spd smallint, Head smallint, PulseValue bigint, Oil float, TSW1 bigint, TSW1Mask bigint, TSW2 bigint, TSW2Mask, BSW bigint, StateText varchar(200), PosText varchar(200), UploadType tinyint

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  • Query to return substring from string in SQL Server

    - by Jowie
    I have a user defined function called Sync_CheckData under Scalar-valued functions in Microsoft SQL Server. What it actually does is to check the quantity of issued product and balance quantity are the same. If something is wrong, returns an ErrorStr nvarchar(255). Output Example: Balance Stock Error for Product ID : 4 From the above string, I want to get 4 so that later on I can SELECT the rows which is giving errors by using WHERE clause (WHERE Product_ID = 4). Which SQL function can I use to get the substring?

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  • Cannot find the certificate

    - by user409756
    We get a T-SQL (SQL Server 2008 R2) error on BACKUP CERTIFICATE: ERROR_NUMBER 15151, SEVERITY 16, STATE 1, PROCEDURE -, LINE 8, MESSAGE: Cannot find the certificate 'certificate1', because it does not exist or you do not have permission. We can see the certificate in master.sys.certificates. Our pseudo-code: copy an unattached template_db to db1 attach db1 create certificate1 (in stored procedure in master db) generate @password CREATE DATABASE ENCRYPTION KEY … ENCRYPTION BY SERVER CERTIFICATE '+@certificate_name +… (in stored procedure in db1) turn on Transparent Database Encryption for db1 using certificate1. (N'ALTER DATABASE '+@db_name+N' SET ENCRYPTION ON') N’BACKUP CERTIFICATE '+@certificate_name+N' TO FILE = '''+@certificate_file_path+N''' WITH PRIVATE KEY ( FILE = '''+@private_key_file_path+N''', ENCRYPTION BY PASSWORD = '''+@password+N'''' To try to work-around the error, we tested three ways with the BACKUP CERTIFICATE code in a different databases each time, including db1 and master. All get the same error. Any ideas? Thanks.

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  • Loop through non-integer rows using SQL

    - by Jesse
    I know how to accomplish my task with .NET, but I wanted to do this just in SQL. I need to loop through all of the rows where the primary key is somewhat arbitrary. It can be a number or a series of letters, and probably any number of unusual things. I know I could do something like this... DECLARE @numRows INT SET @numRows = (SELECT COUNT(pkField) FROM myTable) DECLARE @I INT SET @I = 1 WHILE (@I <= @numRows) BEGIN --Do what I need to here SET @I = @I + 1 END ...if my rows were indexed in a contiguous fashion, but I don't know enough about SQL to do that if they're not. I keep coming across the use of "cursors," but I come across just as much reading about avoiding cursors. I found this SO solution but I'm not sure if that's what I'm needing? I appreciate any ideas.

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  • See queries that hit SQL

    - by Shaded
    I have a really basic stupid easy question about sql... and I'll probably get -100 points... but here it goes anyway... Is there a way using sql 2008 Management Studio to look at the queries that hit the server? I'm trying to debug a program and I get messages like "Incorrect syntax near the keyword 'AND'". Since the queries are being dynamically generated it's a hassle to figure out what is going to the server. Any help is appreciated!

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  • How would I duplicate the Rank function in a Sql Server Compact Edition SELECT statement?

    - by AMissico
    It doesn't look like SQL Server Compact Edition supports the RANK() function. (See Functions (SQL Server Compact Edition) at http://msdn.microsoft.com/en-us/library/ms174077(SQL.90).aspx). How would I duplicate the RANK() function in a SQL Server Compact Edition SELECT statement. (Please use Northwind.sdf for any sample select statements, as it is the only one I can open with SQL Server 2005 Management Studio.)

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  • How to Create Views for All Tables with Oracle SQL Developer

    - by thatjeffsmith
    Got this question over the weekend via a friend and Oracle ACE Director, so I thought I would share the answer here. If you want to quickly generate DDL to create VIEWs for all the tables in your system, the easiest way to do that with SQL Developer is to create a data model. Wait, why would I want to do this? StackOverflow has a few things to say on this subject… So, start with importing a data dictionary. Step One: Open of Create a Model In SQL Developer, go to View – Data Modeler – Browser. Then in the browser panel, expand your design and create a new Relational Model. Step Two: Import your Data Dictionary This is a fancy way of saying, ‘suck objects out of the database into my model’ This will open a wizard to connect, select your schema(s), objects, etc. Once they’re in your model, you’re ready to cook with gas I’m using HR (Human Resources) for this example. You should end up with something that looks like this. Our favorite HR model Now we’re ready to generate the views! Step Three: Auto-generate the Views Go to Tools – Data Modeler – Table to View Wizard. I don’t want all my tables included, and I want to change the naming standard Decide if you want to change the default generated view names By default the views will be created as ‘V_TABLE_NAME.’ If you don’t like the ‘V_’ you can enter your own. You also can reference the object and model name with variables as shown in the screenshot above. I’m going to go with something a little more personal. The views are the little green boxes in the diagram Can’t find your views? They should be grouped together in your diagram. Don’t forget to use the Navigator to easily find and navigate to those model diagram objects! Step Four: Generate the DDL Ok, let’s use the Generate DDL button on the toolbar. Un-check everything but your views If you used a prefix, take advantage of that to create a filter. You might have existing views in your model that you don’t want to include, right? Once you click ‘OK’ the DDL will be generated. -- Generated by Oracle SQL Developer Data Modeler 4.0.0.825 -- at: 2013-11-04 10:26:39 EST -- site: Oracle Database 11g -- type: Oracle Database 11g CREATE OR REPLACE VIEW HR.TJS_BLOG_COUNTRIES ( COUNTRY_ID , COUNTRY_NAME , REGION_ID ) AS SELECT COUNTRY_ID , COUNTRY_NAME , REGION_ID FROM HR.COUNTRIES ; CREATE OR REPLACE VIEW HR.TJS_BLOG_EMPLOYEES ( EMPLOYEE_ID , FIRST_NAME , LAST_NAME , EMAIL , PHONE_NUMBER , HIRE_DATE , JOB_ID , SALARY , COMMISSION_PCT , MANAGER_ID , DEPARTMENT_ID ) AS SELECT EMPLOYEE_ID , FIRST_NAME , LAST_NAME , EMAIL , PHONE_NUMBER , HIRE_DATE , JOB_ID , SALARY , COMMISSION_PCT , MANAGER_ID , DEPARTMENT_ID FROM HR.EMPLOYEES ; CREATE OR REPLACE VIEW HR.TJS_BLOG_JOBS ( JOB_ID , JOB_TITLE , MIN_SALARY , MAX_SALARY ) AS SELECT JOB_ID , JOB_TITLE , MIN_SALARY , MAX_SALARY FROM HR.JOBS ; CREATE OR REPLACE VIEW HR.TJS_BLOG_JOB_HISTORY ( EMPLOYEE_ID , START_DATE , END_DATE , JOB_ID , DEPARTMENT_ID ) AS SELECT EMPLOYEE_ID , START_DATE , END_DATE , JOB_ID , DEPARTMENT_ID FROM HR.JOB_HISTORY ; CREATE OR REPLACE VIEW HR.TJS_BLOG_LOCATIONS ( LOCATION_ID , STREET_ADDRESS , POSTAL_CODE , CITY , STATE_PROVINCE , COUNTRY_ID ) AS SELECT LOCATION_ID , STREET_ADDRESS , POSTAL_CODE , CITY , STATE_PROVINCE , COUNTRY_ID FROM HR.LOCATIONS ; CREATE OR REPLACE VIEW HR.TJS_BLOG_REGIONS ( REGION_ID , REGION_NAME ) AS SELECT REGION_ID , REGION_NAME FROM HR.REGIONS ; -- Oracle SQL Developer Data Modeler Summary Report: -- -- CREATE TABLE 0 -- CREATE INDEX 0 -- ALTER TABLE 0 -- CREATE VIEW 6 -- CREATE PACKAGE 0 -- CREATE PACKAGE BODY 0 -- CREATE PROCEDURE 0 -- CREATE FUNCTION 0 -- CREATE TRIGGER 0 -- ALTER TRIGGER 0 -- CREATE COLLECTION TYPE 0 -- CREATE STRUCTURED TYPE 0 -- CREATE STRUCTURED TYPE BODY 0 -- CREATE CLUSTER 0 -- CREATE CONTEXT 0 -- CREATE DATABASE 0 -- CREATE DIMENSION 0 -- CREATE DIRECTORY 0 -- CREATE DISK GROUP 0 -- CREATE ROLE 0 -- CREATE ROLLBACK SEGMENT 0 -- CREATE SEQUENCE 0 -- CREATE MATERIALIZED VIEW 0 -- CREATE SYNONYM 0 -- CREATE TABLESPACE 0 -- CREATE USER 0 -- -- DROP TABLESPACE 0 -- DROP DATABASE 0 -- -- REDACTION POLICY 0 -- -- ERRORS 0 -- WARNINGS 0 You can then choose to save this to a file or not. This has a few steps, but as the number of tables in your system increases, so does the amount of time this feature can save you!

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  • System Variables, Stored Procedures or Functions for Meta Data

    - by BuckWoody
    Whenever you want to know something about SQL Server’s configuration, whether that’s the Instance itself or a database, you have a few options. If you want to know “dynamic” data, such as how much memory or CPU is consumed or what a particular query is doing, you should be using the Dynamic Management Views (DMVs) that you can read about here: http://msdn.microsoft.com/en-us/library/ms188754.aspx  But if you’re looking for how much memory is installed on the server, the version of the Instance, the drive letters of the backups and so on, you have other choices. The first of these are system variables. You access these with a SELECT statement, and they are useful when you need a discrete value for use, say in another query or to put into a table. You can read more about those here: http://msdn.microsoft.com/en-us/library/ms173823.aspx You also have a few stored procedures you can use. These often bring back a lot more data, pre-formatted for the screen. You access these with the EXECUTE syntax. It is a bit more difficult to take the data they return and get a single value or place the results in another table, but it is possible. You can read more about those here: http://msdn.microsoft.com/en-us/library/ms187961.aspx Yet another option is to use a system function, which you access with a SELECT statement, which also brings back a discrete value that you can use in a test or to place in another table. You can read about those here: http://msdn.microsoft.com/en-us/library/ms187812.aspx  By the way, many of these constructs simply query from tables in the master or msdb databases for the Instance or the system tables in a user database. You can get much of the information there as well, and there are even system views in each database to show you the meta-data dealing with structure – more on that here: http://msdn.microsoft.com/en-us/library/ms186778.aspx  Some of these choices are the only way to get at a certain piece of data. But others overlap – you can use one or the other, they both come back with the same data. So, like many Microsoft products, you have multiple ways to do the same thing. And that’s OK – just research what each is used for and how it’s intended to be used, and you’ll be able to select (pun intended) the right choice. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Export all SSIS packages from msdb using Powershell

    - by jamiet
    Have you ever wanted to dump all the SSIS packages stored in msdb out to files? Of course you have, who wouldn’t? Right? Well, at least one person does because this was the subject of a thread (save all ssis packages to file) on the SSIS forum earlier today. Some of you may have already figured out a way of doing this but for those that haven’t here is a nifty little script that will do it for you and it uses our favourite jack-of-all tools … Powershell!! Imagine I have the following package folder structure on my Integration Services server (i.e. in [msdb]): There are two packages in there called “20110111 Chaining Expression components” & “Package”, I want to export those two packages into a folder structure that mirrors that in [msdb]. Here is the Powershell script that will do that:Param($SQLInstance = "localhost") #####Add all the SQL goodies (including Invoke-Sqlcmd)##### add-pssnapin sqlserverprovidersnapin100 -ErrorAction SilentlyContinue add-pssnapin sqlservercmdletsnapin100 -ErrorAction SilentlyContinue cls $Packages = Invoke-Sqlcmd -MaxCharLength 10000000 -ServerInstance $SQLInstance -Query "WITH cte AS ( SELECT cast(foldername as varchar(max)) as folderpath, folderid FROM msdb..sysssispackagefolders WHERE parentfolderid = '00000000-0000-0000-0000-000000000000' UNION ALL SELECT cast(c.folderpath + '\' + f.foldername as varchar(max)), f.folderid FROM msdb..sysssispackagefolders f INNER JOIN cte c ON c.folderid = f.parentfolderid ) SELECT c.folderpath,p.name,CAST(CAST(packagedata AS VARBINARY(MAX)) AS VARCHAR(MAX)) as pkg FROM cte c INNER JOIN msdb..sysssispackages p ON c.folderid = p.folderid WHERE c.folderpath NOT LIKE 'Data Collector%'" Foreach ($pkg in $Packages) { $pkgName = $Pkg.name $folderPath = $Pkg.folderpath $fullfolderPath = "c:\temp\$folderPath\" if(!(test-path -path $fullfolderPath)) { mkdir $fullfolderPath | Out-Null } $pkg.pkg | Out-File -Force -encoding ascii -FilePath "$fullfolderPath\$pkgName.dtsx" } To run it simply change the “localhost” parameter of the server you want to connect to either by editing the script or passing it in when the script is executed. It will create the folder structure in C:\Temp (which you can also easily change if you so wish – just edit the script accordingly). Here’s the folder structure that it created for me: Notice how it is a mirror of the folder structure in [msdb]. Hope this is useful! @Jamiet UPDATE: THis post prompted Chad Miller to write a post describing his Powershell add-in that utilises a SSIS API to do exporting of packages. Go take a read here: http://sev17.com/2011/02/importing-and-exporting-ssis-packages-using-powershell/

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  • Export all SSIS packages from msdb using Powershell

    - by jamiet
    Have you ever wanted to dump all the SSIS packages stored in msdb out to files? Of course you have, who wouldn’t? Right? Well, at least one person does because this was the subject of a thread (save all ssis packages to file) on the SSIS forum earlier today. Some of you may have already figured out a way of doing this but for those that haven’t here is a nifty little script that will do it for you and it uses our favourite jack-of-all tools … Powershell!!   Imagine I have the following package folder structure on my Integration Services server (i.e. in [msdb]): There are two packages in there called “20110111 Chaining Expression components” & “Package”, I want to export those two packages into a folder structure that mirrors that in [msdb]. Here is the Powershell script that will do that:   Param($SQLInstance = "localhost") #####Add all the SQL goodies (including Invoke-Sqlcmd)##### add-pssnapin sqlserverprovidersnapin100 -ErrorAction SilentlyContinue add-pssnapin sqlservercmdletsnapin100 -ErrorAction SilentlyContinue cls $Packages = Invoke-Sqlcmd -MaxCharLength 10000000 -ServerInstance $SQLInstance -Query "WITH cte AS ( SELECT cast(foldername as varchar(max)) as folderpath, folderid FROM msdb..sysssispackagefolders WHERE parentfolderid = '00000000-0000-0000-0000-000000000000' UNION ALL SELECT cast(c.folderpath + '\' + f.foldername as varchar(max)), f.folderid FROM msdb..sysssispackagefolders f INNER JOIN cte c ON c.folderid = f.parentfolderid ) SELECT c.folderpath,p.name,CAST(CAST(packagedata AS VARBINARY(MAX)) AS VARCHAR(MAX)) as pkg FROM cte c INNER JOIN msdb..sysssispackages p ON c.folderid = p.folderid WHERE c.folderpath NOT LIKE 'Data Collector%'" Foreach ($pkg in $Packages) { $pkgName = $Pkg.name $folderPath = $Pkg.folderpath $fullfolderPath = "c:\temp\$folderPath\" if(!(test-path -path $fullfolderPath)) { mkdir $fullfolderPath | Out-Null } $pkg.pkg | Out-File -Force -encoding ascii -FilePath "$fullfolderPath\$pkgName.dtsx" }   To run it simply change the “localhost” parameter of the server you want to connect to either by editing the script or passing it in when the script is executed. It will create the folder structure in C:\Temp (which you can also easily change if you so wish – just edit the script accordingly). Here’s the folder structure that it created for me: Notice how it is a mirror of the folder structure in [msdb]. Hope this is useful! @Jamiet

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  • My server is slower than the average user's computer, should I still offload Access queries to SQL Server? [closed]

    - by andrewb
    Possible Duplicate: How do you do Load Testing and Capacity Planning for Databases I have a database set up with MS Access 2007 front ends and an SQL Server 2005 back end. At the moment, all the queries are saved in the front end as I've only recently moved to an SQL Server backend. I'm wondering how much of those queries I should save as stored procedures/views on SQL Server. About the system The number of concurrent users is only a handful, though it could be as high as 25 at one time (very unlikely). The average computer has an Intel i3-2120 CPU running at 3.3 GHz, which gets a PassMark score of 3,987, whilst the server has an Intel Xeon E5335 running at 2.0 GHz, which gets a PassMark score of 2,637. Always an awkward situation when an i3 outperforms a Xeon... though the i3 is from Q1 2011 and the Xeon is Q2 2009. There is potential for a server upgrade in the future, though it wouldn't come easy. I'm inclined to move the queries to the back end, as they are beginning to take noticeable time and I figure that is a better way of doing things. I like the idea of throwing everything at the server, then pushing for a server upgrade. It makes more sense in my mind to be upgrading one server rather than 30 PCs. Or am I being overzealous? Why my question isn't a duplicate It seems that my question has been misinterpreted and labelled a duplicate of quite a different question, one about testing and capacity planning. I'll try explain how my question is very different from the linked question. The crux of my question is something like "Even though my server is technically slower, is it better to have it doing more of the queries?" There's two ways that people could have answered this: I agree the server is going to be slower, but the extra benefits of such and such (like the less Access the better) means you should move most to the server anyway. (OR no it doesn't outweigh the benefit, keep them in Access) Actually the server will be faster because of such and such. I'm hoping that people out there could provide some answers like this, and the question in the dupe link doesn't really provide either of these answers. Ok sure, I suppose I could do extensive performance testing to compare Access queries running on a local machine to SQL Server queries running on the server, but that sounds like a very hard task (particularly performance testing of access) compared to someone giving some quick general guidance, and again, my question is looking for a lot more than immediate performance benefit.

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  • Install Sql Server Developer Edition 32-bit (or Enterprise Edition) on Windows 7 Home Premium 64-bit

    - by ali62b
    Is there any work around to Successfully install SQL server 2008 32-bit on Windows 7 Home premium 64-bit ? If this is the case I first installed VS 2008 SP 1 on my machine and when I click on install.exe file for installing SQL Server 2008 (Developer Edition) I get an error related to .NET Framework version which is installed already on my PC. { I get the same error trying to install Enterprise Edition}

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  • How do I get SQL Profiler to show statements with column names like 'password'?

    - by Kev
    I'm profiling a database just now and need to see the UPDATE and INSERT statements being executed on a particular table. However, because the table has a 'Password' column the SQL Profiler is being understandingly cautious and replacing the TextData column with: -- 'password' was found in the text of this event. -- The text has been replaced with this comment for security reasons. How do I prevent it doing this because I need to see the SQL statement being executed?

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  • SQL Server Express with Advanced Services (with Reporting Services)???

    - by Fretwizard
    I have tried to download SQL Server 2005 Express edition about 4 times trying to find the correct version that has business intelligence studio and reporting services in it? Every time I try to unhide the advanced configuration during install, it's never there... Can anyone point me to the correct download? Looking for 2005 (not 2008) because my work SQL server that I am trying to learn this for is 2005, and the training material I have is for 2005 and VS 2008 does not want to integrate with SQL2008 express.

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  • Alias a linked Server in SQL server management studio?

    - by absentmindeduk
    Hoping someone can help - is there a way in SQL server management studio 2008 R2 that I can alias a linked SQL server? I have a server, added by IP address, to which I do not have the login credentials - however as the connection is already setup I can login ok. Issue is that, this is a dev environment, prior to a live deployment and the IP I have as a linked server needs to be 'accessible' by my stored procs under a different name, eg 'myserver' not 192.168.xxx.xxx... Any help much appreciated.

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  • Joins in single-table queries

    - by Rob Farley
    Tables are only metadata. They don’t store data. I’ve written something about this before, but I want to take a viewpoint of this idea around the topic of joins, especially since it’s the topic for T-SQL Tuesday this month. Hosted this time by Sebastian Meine (@sqlity), who has a whole series on joins this month. Good for him – it’s a great topic. In that last post I discussed the fact that we write queries against tables, but that the engine turns it into a plan against indexes. My point wasn’t simply that a table is actually just a Clustered Index (or heap, which I consider just a special type of index), but that data access always happens against indexes – never tables – and we should be thinking about the indexes (specifically the non-clustered ones) when we write our queries. I described the scenario of looking up phone numbers, and how it never really occurs to us that there is a master list of phone numbers, because we think in terms of the useful non-clustered indexes that the phone companies provide us, but anyway – that’s not the point of this post. So a table is metadata. It stores information about the names of columns and their data types. Nullability, default values, constraints, triggers – these are all things that define the table, but the data isn’t stored in the table. The data that a table describes is stored in a heap or clustered index, but it goes further than this. All the useful data is going to live in non-clustered indexes. Remember this. It’s important. Stop thinking about tables, and start thinking about indexes. So let’s think about tables as indexes. This applies even in a world created by someone else, who doesn’t have the best indexes in mind for you. I’m sure you don’t need me to explain Covering Index bit – the fact that if you don’t have sufficient columns “included” in your index, your query plan will either have to do a Lookup, or else it’ll give up using your index and use one that does have everything it needs (even if that means scanning it). If you haven’t seen that before, drop me a line and I’ll run through it with you. Or go and read a post I did a long while ago about the maths involved in that decision. So – what I’m going to tell you is that a Lookup is a join. When I run SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 285; against the AdventureWorks2012 get the following plan: I’m sure you can see the join. Don’t look in the query, it’s not there. But you should be able to see the join in the plan. It’s an Inner Join, implemented by a Nested Loop. It’s pulling data in from the Index Seek, and joining that to the results of a Key Lookup. It clearly is – the QO wouldn’t call it that if it wasn’t really one. It behaves exactly like any other Nested Loop (Inner Join) operator, pulling rows from one side and putting a request in from the other. You wouldn’t have a problem accepting it as a join if the query were slightly different, such as SELECT sod.OrderQty FROM Sales.SalesOrderHeader AS soh JOIN Sales.SalesOrderDetail as sod on sod.SalesOrderID = soh.SalesOrderID WHERE soh.SalesPersonID = 285; Amazingly similar, of course. This one is an explicit join, the first example was just as much a join, even thought you didn’t actually ask for one. You need to consider this when you’re thinking about your queries. But it gets more interesting. Consider this query: SELECT SalesOrderID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276 AND CustomerID = 29522; It doesn’t look like there’s a join here either, but look at the plan. That’s not some Lookup in action – that’s a proper Merge Join. The Query Optimizer has worked out that it can get the data it needs by looking in two separate indexes and then doing a Merge Join on the data that it gets. Both indexes used are ordered by the column that’s indexed (one on SalesPersonID, one on CustomerID), and then by the CIX key SalesOrderID. Just like when you seek in the phone book to Farley, the Farleys you have are ordered by FirstName, these seek operations return the data ordered by the next field. This order is SalesOrderID, even though you didn’t explicitly put that column in the index definition. The result is two datasets that are ordered by SalesOrderID, making them very mergeable. Another example is the simple query SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276; This one prefers a Hash Match to a standard lookup even! This isn’t just ordinary index intersection, this is something else again! Just like before, we could imagine it better with two whole tables, but we shouldn’t try to distinguish between joining two tables and joining two indexes. The Query Optimizer can see (using basic maths) that it’s worth doing these particular operations using these two less-than-ideal indexes (because of course, the best indexese would be on both columns – a composite such as (SalesPersonID, CustomerID – and it would have the SalesOrderID column as part of it as the CIX key still). You need to think like this too. Not in terms of excusing single-column indexes like the ones in AdventureWorks2012, but in terms of having a picture about how you’d like your queries to run. If you start to think about what data you need, where it’s coming from, and how it’s going to be used, then you will almost certainly write better queries. …and yes, this would include when you’re dealing with regular joins across multiples, not just against joins within single table queries.

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  • MERGE gives better OUTPUT options

    - by Rob Farley
    MERGE is very cool. There are a ton of useful things about it – mostly around the fact that you can implement a ton of change against a table all at once. This is great for data warehousing, handling changes made to relational databases by applications, all kinds of things. One of the more subtle things about MERGE is the power of the OUTPUT clause. Useful for logging.   If you’re not familiar with the OUTPUT clause, you really should be – it basically makes your DML (INSERT/DELETE/UPDATE/MERGE) statement return data back to you. This is a great way of returning identity values from INSERT commands (so much better than SCOPE_IDENTITY() or the older (and worse) @@IDENTITY, because you can get lots of rows back). You can even use it to grab default values that are set using non-deterministic functions like NEWID() – things you couldn’t normally get back without running another query (or with a trigger, I guess, but that’s not pretty). That inserted table I referenced – that’s part of the ‘behind-the-scenes’ work that goes on with all DML changes. When you insert data, this internal table called inserted gets populated with rows, and then used to inflict the appropriate inserts on the various structures that store data (HoBTs – the Heaps or B-Trees used to store data as tables and indexes). When deleting, the deleted table gets populated. Updates get a matching row in both tables (although this doesn’t mean that an update is a delete followed by an inserted, it’s just the way it’s handled with these tables). These tables can be referenced by the OUTPUT clause, which can show you the before and after for any DML statement. Useful stuff. MERGE is slightly different though. With MERGE, you get a mix of entries. Your MERGE statement might be doing some INSERTs, some UPDATEs and some DELETEs. One of the most common examples of MERGE is to perform an UPSERT command, where data is updated if it already exists, or inserted if it’s new. And in a single operation too. Here, you can see the usefulness of the deleted and inserted tables, which clearly reflect the type of operation (but then again, MERGE lets you use an extra column called $action to show this). (Don’t worry about the fact that I turned on IDENTITY_INSERT, that’s just so that I could insert the values) One of the things I love about MERGE is that it feels almost cursor-like – the UPDATE bit feels like “WHERE CURRENT OF …”, and the INSERT bit feels like a single-row insert. And it is – but into the inserted and deleted tables. The operations to maintain the HoBTs are still done using the whole set of changes, which is very cool. And $action – very convenient. But as cool as $action is, that’s not the point of my post. If it were, I hope you’d all be disappointed, as you can’t really go near the MERGE statement without learning about it. The subtle thing that I love about MERGE with OUTPUT is that you can hook into more than just inserted and deleted. Did you notice in my earlier query that my source table had a ‘src’ field, that wasn’t used in the insert? Normally, this would be somewhat pointless to include in my source query. But with MERGE, I can put that in the OUTPUT clause. This is useful stuff, particularly when you’re needing to audit the changes. Suppose your query involved consolidating data from a number of sources, but you didn’t need to insert that into the actual table, just into a table for audit. This is now very doable, either using the INTO clause of OUTPUT, or surrounding the whole MERGE statement in brackets (parentheses if you’re American) and using a regular INSERT statement. This is also doable if you’re using MERGE to just do INSERTs. In case you hadn’t realised, you can use MERGE in place of an INSERT statement. It’s just like the UPSERT-style statement we’ve just seen, except that we want nothing to match. That’s easy to do, we just use ON 1=2. This is obviously more convoluted than a straight INSERT. And it’s slightly more effort for the database engine too. But, if you want the extra audit capabilities, the ability to hook into the other source columns is definitely useful. Oh, and before people ask if you can also hook into the target table’s columns... Yes, of course. That’s what deleted and inserted give you.

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  • .Net Windows Service Throws EventType clr20r3 system.data.sqlclient.sql error

    - by William Edmondson
    I have a .Net/c# 2.0 windows service. The entry point is wrapped in a try catch block yet when I look at the server's application event log I seem a number of "EventType clr20r3" errors that are causing the service to die unexpectedly. The catch block has a "catch (Exception ex)". Each sql commands is of the type "CommandType.StoredProcedure" and are executed with SqlDataReader's. These sproc calls function correctly 99% of time and have all been thoroughly unit tested, profiled, and QA'd. I additionally wrapped these calls in try catch blocks just to be sure and am still experiencing these unhandled exceptions. This only in our production environment and cannot be duplicated in our dev or staging environments (even under heavy load). Why would my error handling not catch this particular error? Is there anyway to capture more detail as to the root cause of the problem? Here is an example of the event log: EventType clr20r3, P1 RDC.OrderProcessorService, P2 1.0.0.0, P3 4ae6a0d0, P4 system.data, P5 2.0.0.0, P6 4889deaf, P7 2490, P8 2c, P9 system.data.sqlclient.sql, P10 NIL. Additionally The Order Processor service terminated unexpectedly. It has done this 1 time(s). The following corrective action will be taken in 60000 milliseconds: Restart the service.

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  • LINQ To SQL ignore unique constraint exception and continue

    - by Martin
    I have a single table in a database called Users Users ------ ID (PK, Identity) Username (Unique Index) I have setup a unique index on the Username table to prevent duplicates. I am then enumerating through a collection and creating a new user in the database for each item. What I want to do is just insert a new user and ignore the exception if the unique key constraint is violated (as it's clearly a duplicate record in that case). This is to avoid having to craft where not exists kind of queries. First off, is this going to be any more efficient or should my insert code be checking for duplicates instead? I'm drawn more to the database having that logic as this prevents any other type of client from inserting duplicate data. My other issue is related to LINQ To SQL. I have the following code: public class TestRepo { DatabaseDataContext database = new DatabaseDataContext(); public void Add(string username) { database.Users.InsertOnSubmit(new User() { Username = username }); } public void Save() { database.SubmitChanges(); } } And then I iterate over a collection and insert new users, ignoring any exceptions: TestRepo repo = new TestRepo(); foreach (var name in new string[] { "Tim", "Bob", "John" }) { try { repo.Add(name); repo.Save(); } catch { } } The first time this is run, great I have three users in the table. If I remove the second one and run this code again, nothing is inserted. I expected the first insert to fail with the exception, the second to succeed (as I just removed that item from the DB) and the third to then fail. What seems to be happening is that once the SqlException is thrown (even though the loop continues to iterate) all of the next inserts fail - even when there isn't a row in the table that would cause a unique violation. Can anyone explain this? P.S. The only workaround I could find was to instantiate the repo each time before the insert, then it worked exactly as excepted - indicating that it's something to do with the LINQ To SQL DataContext. Thanks.

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