DataAdaptor/Dataset When No Row Present In Database Tables
Apr 21, 2010
I'm trying to use a DataSet to maintain some rows for a table, and when I've finished my changes, send all changes to the database using a SqlDataAdapter.
I find if there are no rows in the table in the database then I am getting a 'Object reference not set to an instance of an object' when I try to access the table in the Dataset.
Is there a way to work with a Dataset like this ie. I start off with an empty table and I wish to add rows, to access the structure of the table rows, build rows, then add them and do the update on the SQLDataAdapter.
I am using DataAdapter.FillSchema to create shema of tables in DataSet. I created DataRelation on columns T1id in both tables.
Now when i try to Update Sql Database T1id in Table2 remains 0 and not the value of T1id in Table1.
I can successfully update Sql Database if i fill DataSet with records first (Using DataAdapter.Fill), but that's not what i want to do. I don't need "old" records in my dataset. I want to use dataset just to store all imputs from user until the proccess is done and then insert all those records "at the same time".
I am getting Resultset from SQL server2005.It contains 4 tables.
Dataset ds=new Dataset();
ds=BLogiclayer1.TestMethod1(a,b,c,d);. This normal Dataset ds contains Resultset. ( I am working with RDLC reports. I added a Typed dataset to my project. I am using Typed Dataset as report dataset.) I want to add normal Dataset all the table values to Typed Dataset table as rows i. e. only one table in Typed dataset.I am trying like below.
//Typed Dataset name that I have added is salesdata.
I am developing web application using asp.net. Here i need to access two databases in which one is present on other server. I am able to connect to database present in same server but not with database present in other server.
I am using MS-access. I dont know the changes to be done and syntax for database connection.
I'm currently developing a website using VS2010 Express/SQL Express 2008, and am using the applications development server to test.
I have created an access layer which effectively takes all my cachable data and creates datasets.
I've also created a system wheras for each dataset, For each dataset I also create a token cached object (a string), which is set to expire before the dataset. The theory behind this is that when my token expires and is removed from cache, it calls a routine to rebuild the dataset, and re-caches the new result, then creates a new token. Think of it as a poor mans SQL dependency.
What this allows me to do is rebuild datasets behind the scenes with little interruption/delay throughout the day. It all works great - for instance when a user updates a table containing 100,000+ records on the site, the dataset rebuilds at hourly intervals reworking and consolidating the data in the background before representing it in a smaller cachable form.
What I would like to know is this. If I was to replace the database during the usable day (only updating the tables that users don't update), lets say adding 50 new records, would it cause the cache to be dropped. The reason I ask is because it the cache remains until its exipry time, I can replace the database and rebuild datasets incorporating new data in the background when the token expires. If the cache is dropped when I update the database, it will mean interuption whilst I reload the datasets and will change my strategy on uploading new data.
I ask the question because I'm currently working on the development server and unable to test in a live server environment at present.
I have 5 tables of which one has a primary key called "pid" as follows in patientdetails table the pid of a patient is used to compare the pid in remaining tables so the data in matching pid records can be stored in dataset. I tried using stored procedure to get them together in one dataset but it just doesent happen. This is my stored procedure,
[Code]....
I think the execution doesent proceed after the first if exists statements, because only the data in patientdetails is stored in dataset. and one more thing. all test tables need not contain a data against every pid in patientdetails table.
In my project, i have a DBML file which is acting as a Data Access Layer. There one more utility method that is converting the existing result into dataset. Below is my method:
I have a C# problem I need to synchronize two MS Access tables from two different databases(two databases over a network) which is quite similar, I thought of using two different OleDbConnections and two DataAdapters to fill a Single DataSet and then manipulate the data in the DataSet, I think the source table (database with the primary data) should be loaded first (into the DataSet) then the secondary table from the remote database should subtract the existing records in the DataSet to get the difference then the difference should be Appended to the remote table, but I don't know how to remove the same records from the DataSet and to send the remaining records to the secondary database.
Here is some code I already have, but I don't know how to get this to work:
Does anyone have some really great tutorials on how to use link with datasets that contain multiple tables that utilise primary key and foreign key relations? For eample
Table1 - id (PK) - language Table2 -id (PK) -programmingword Table3 -id (PK) -languages_ID (FK) -pgrammingword_ID (FK) -translatedword
Linq search for: Table3.translatedword where Table1.Language ='french' and Table2.programmingword = "yes" does this make sense? im looking for exampes/ tutorials for how to do this? or can anyone recommend any good books on linq?
When i try to insert a my database's table in my dataset, it doesn't generate the update command like had done with other tables. It generates only insert and select commands
How can i do to generate it without write it manually?
my requirement is : am having a excel sheet with some values listed i want to pass each value present in any(specified) column to a text box present on a remote page (a site other than mine) as a input and capture the result displayed on the page and then store the input and reuslt side by side in db this should repeat till the end of the input values in the excel sheet.
I have a members section of a website where when they first register to become a member, they pick their top 5 sports personalities/stars. Then when they log in to the members area, I want to display members news which should show:
- at the top all new stories that have been their sportstar has been referenced to
- then all other news
(In the CMS, admins can edit a news story and they have 5 dropdowns of all the sportstars so they can for example have for a news story: Sportstar1=Tiger Woods, Sportstar2=David Beckham etc) So as a member, if I have selected David Beckham as one of my top 5s, then all news tagged with him via the CMS are displayed.
There may be a better way to approach it, but basically I am creating one DataSet, then firing off 5 SQL queries, each SQL query is like this:
[Code]....
Then in my Page Load I do this:
[Code]....
The problem is that my repeater is inl showing news for myStar1 i.e. it is nly showing the first table which will be called "News1".
So is there any easier way of doing this? Am I overcomplicating things?
I have a dataset with 3 tables that are inner joined. Thsi dataset is connected to an object datasource which is connected to a gridview. So at runtime it displays data from the database. The problem is when I click on a save button to add information to the database it throughs me an error saying Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. But if i have two tables in my dataset it works 100%. But the problem i need that 3 tables in order to pull the required information. And if i populate the gridview using code to select the information from the database and insert information it also works 100%.
I would like to update new records that get inserted in DataSet to Sql Server Database. Below is a working example of how to do this if you use "DataAdapter.Fill(ds)".
But i don't want to fill data, becouse i don't need data, i only need shema (I will use this dataset to insert new data to Sql), so i would like to use "DataAdapter.FillSchema(ds)"
Here's the scenario: Buyers and Sellers (where all of the sellers have a unique D&B number).
I'm catering to the buyers, and I want them to be able to import a list of sellers based on the D&B number.
Here are the tables:
BuyersSellers - unique list of sellers - one record, no matter how many buyers work with them.BuyerSellers - lookup table - buyer_id, seller_id sets which buyers work with which sellers ImportedSellers - temp table that holds sellers the buyer wants to add.AllSellers - master table that has all known sellers with D&B numbers (remote database).
Here's the process:
Buyer uploads list of new sellers, they get added to ImportSellers tableMatch ImportedSellers against AllSellers (valid), ignore unmatched (invalid).Add valid ImportedSellers to the Sellers table if they don't exist.Create BuyerSeller records for all valid ImportedSellers - using data from AllSellers.Delete all valid ImportedSellers, leave the unmatched behind so they know what they need to fix.
I've got the upload and import working, but now I'm a little stuck on how to do all of the matching and inserting, and do it as quickly as possible.
I have a dataset that comprises of multiple tables (about 20) linked together with constraints to reflect the relational database. My question(s):
1) Will having multiple tables affect performance? I'm asking this as there are often times I would not need to get data for all the tables, but only for specific tables.
2) If it does affect performance, would breaking up the tables into their own datasets be the best solution. It seems to me that by doing that, you would lose the ability to apply constraints among tables and tables that might exist in multiple datasets will be subjected to replication.
I would like to have everything in one dataset as I get a view of the related tables and their relationships and also because the Fill method allow me to fill tables, maintaining the hierarchy of the data, but performance is still a key factor.
i m trying to bind my both grid with two tables which are in dataset i m trying but when i m binding my gridview it's always binding the second table see code
[Code]....
i already tried to bind both the gv1 and gv2 they both are displaying same table i.e department
i have this xml file which i read using the DataSet.ReadXml( path ) method . The tables created from the Xml file is Related in such a maner that each product has many options. Product is in one table and Options are in another.Now all i want to do is display the related tables in One Gridview. For your reference below is the products Xml file,
[Code]....
Now this is what i have done in the Code behind , have a look below
[Code]....
Now the Grid works Great if i want to Display Individual tables out from Dataset but not when they are related . Please do shine your Knowledge on what should be done to display Child ~ Master relationship. By the way , its a definite NO for someone who would show me that link from msdn about displaying XML data using Xmldatasource and gridview [That's a lousy way to display data]
I have a report which is runnin fine as it is using singe table Dataset(.xsd) . I want to expand the report and use more tables in it to show more information .
How can I do so. I am attaching my present code with this.
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Dim stdate, enddate As Date Dim sql As String start_date.Text = Session("startdate") end_date.Text = Session("endate") Dim dt As DateTime = DateTime.Parse(start_date.Text, System.Globalization.CultureInfo.GetCultureInfo("en-gb"))
My dataset table data is from multiple tables (showing on a gridview),How to update the database tables using batch udpate on clicking submit, if the data is from a signle table, no problem, but I am not sure how to handle if the datais from mulitiple tables? If I have related tables, do I need put them in differet tables in the dataset?