I am working on a site in which as user logs in (first database request) the stored procedure varify password and user id and then returns user record that I put in session to use next.
After this I do a second db request. it returns addresses of user which I put in cache.
Can you pleas guide me is there some way that I can get both sets of data (user record and his address from 2nd table) in one database requests.
plz guide me on this, I am using DAAB (enter prise library) for data access.
Thanks
Modify your SP which has multiple select statements, as in you case is 2. Two select statements in one SP will return two record sets. Verify in SQL Management Studio, when you run your SP, it should show you multiple Grid in bottom panel.
Once your SP is done, call SP from C# code and load result in DataSet. Dataset will have two table, and you can get the data from different table
You can write two select queries in a stored procedure or
Execute two queries one after another . In single query you can execute and receive the data in DataSet .
ExecuteDataset()
So two tables will be returned inside the dataset . You can get the values like
dataset.tables(0)
dataset.tables(1)
Thanks
You would gain nothing from retrieving two results sets in one go, But the code will become more incoherent. Why do you thing you need to merge two logically separate operations into one? Instead of using such questionable methods you can use join to get one result set that contains all the data in one go, but still that seems wrong. I can not see a clean way of doing what you are asking for and any benefits that might be gained.
Related
We have a 4 column data grid display on a page. I would like to perform a query based on each of the values within each cell of the grid i.e. 4 queries for each row.
This is so I can populate the cell with count of records in db that matches that value.
When each row gets populated by jqgrid, it fires off an ajax call for each cell.
I think it's a very bad idea since I have already discovered the browser limits the number of ajax calls to the same server.
Are there similar limits for ado.net?
I would like to batch these queries together so I do fewer calls to the db, is this what you would do?
How would you approach this?
You could combine your AJAX calls into one, the resulting object contains an array, or multiple properties for each result set, and then you run your SQL in parallel on the server.
Check out this QA for how to use options on how to use TPL and SQL.
Parallel.Foreach SQL querying sometimes results in Connection
me would suggest you to select the associated id data in the first request and populate the values in the UI.
You could either use join or left join in your first query based on your requirement and architecture and fetch the specific column value/ count(id) ( Here you mentioned as the count of records ).
I'm developing an ASP.NET app that analyzes Excel files uploaded by user. The files contain various data about customers (one row = one customer), the key field is CustomerCode. Basically the data comes in form of DataTable object.
At some point I need to get information about the specified customers from SQL and compare it to what user uploaded. I'm doing it the following way:
Make a comma-separated list of customers from CustomerCode column: 'Customer1','Customer2',...'CustomerN'.
Pass this string to SQL query IN (...) clause and execute it.
This was working okay until I ran into The query processor ran out of internal resources and could not produce a query plan exception when trying to pass ~40000 items inside IN (...) clause.
The trivial ways seems to:
Replace IN (...) with = 'SomeCustomerCode' in query template.
Execute this query 40000 times for each CustomerCode.
Do DataTable.Merge 40000 times.
Is there any better way to work this problem around?
Note: I can't do IN (SELECT CustomerCode FROM ... WHERE SomeConditions) because the data comes from Excel files and thus cannot be queried from DB.
"Table valued parameters" would be worth investigating, which let you pass in (usually via a DataTable on the C# side) multiple rows - the downside is that you need to formally declare and name the data shape on the SQL server first.
Alternatively, though: you could use SqlBulkCopy to throw the rows into a staging table, and then just JOIN to that table. If you have parallel callers, you will need some kind of session identifier on the row to distinguish between concurrent uses (and: don't forget to remove your session's data afterwards).
You shouldn't process too many records at once, because of errors as you mentioned, and it is such a big batch that it takes too much time to run and you can't do anything in parallel. You shouldn't process only 1 record at a time either, because then the overhead of the SQL server communication will be too big. Choose something in the middle, process eg. 10000 records at a time. You can even parallelize the processing, you can start running the SQL for the next 10000 in the background while you are processing the previous 10000 batch.
I am converting a VB6 app to C# with an SQL Server back end. The app includes a very general query editor that allows the user to write any select query and return the results visually in a grid control. Some of the tables have several hundred columns (poor design, I know but I have no control over this). A typical use case for an admin user would be to
select * from A_Table_With_Many_Columns
However, while they want to be able to view all the data, they are particularly interested in 2 columns and they want these to be displayed as the first 2 columns in the grid (instead of 67th and 99th for example) so instead they execute the following statement:
select First_Interesting_Field, Second_Interesting_Field, *
from A_Table_With_Many_Columns
Then they will go and modify the data in the grid. However, when saving this data, it results in a concurrency violation (DBConcurrencyException). This worked fine with the connected RecordSets of VB6 but not so well in C#. I have tried a myriad of solutions to no avail.
Does anyone know how to handle this exception in a generic way? (Remember, the user can type ANY select statement or join etc. into the query editor)
Does anyone know how I might manipulate the columns returned such that I delete the 2 columns that appear further on in the list? (My difficulty here is that if the column name in the database is EMail so I do select Email, * from Blah the 2 pertinent columns returned are EMail and ADO.NET or C# aliases the second EMail column from the * portion of the query as EMail1 so I am not able to detect the second column as a duplicate and remove it)
Does anyone have an alternate solution I have not thought of?
Thank you very much
Actually, you could rename all variables to something like email_userdefined by doing something like this:
SELECT First_Interesting_Field as First_Interesting_Field_userdefined, Second_Interesting_Field as Second_Interesting_Field_userdefined, *
from A_Table_With_Many_Columns
Replace user_defined with whatever you want, like order number or anything else user acceptable
I have a database with many tables and constraints (but not much data). The database contains a few separate entities that are bound together by an ID directly or indirectly, as illustrated below:
My target is to move one entire slice of data (including data from all tables in the database) to another physical database in an easy and safe way. It's OK if it doesn't perform very well. In the above example, I would want to move the company with a certain Id as well as all employees of that company and all data related to the employees etc. through all the tables.
I want to do it with a safe compile-checked method, as I want to catch errors whenever I change my database.
The IDs in the database are mostly guids, but there are a few tables using auto incremented IDs.
note
The "Companies" table contains perhaps 5 rows, one for each company. I need to move ONE row from that table, along with all data directly or indirectly related to that row.
Suppose you want to copy data from from a detailsview(tableName=Jobs) to another table(tablename=Company)
string apply = "INSERT INTO Company (JobTitle,CompanyName) select JobTitle,CompanyName from Jobs";
this is just an idea hope it help.
UPDATE :
So this will help you
MSDN - Multiple Bulk Copy Operations (ADO.NET)
With example
I'm trying to mimic the functionality of the Query Analyzer piece of the SQL Server Management Studio using .NET. The user will input a SQL script, and the program will run it. If it returns a result set, the program will load that up into a datagrid and show the user.
My question is: Is there a way to return more than one result set from a single script? I know Query Analyzer runs this and loads up multiple datagrids if several result sets are returned, but as far as I know when you try to do this with SqlDataAdapter.Fill(...), it only returns the last result set in the script.
This will show you how to return multiple result sets: http://vb.net-informations.com/ado.net-dataproviders/ado.net-multiple-result-sets.htm
You loop through the different result sets using the sqlReader.NextResult() method. You can then use sqlReader.Read() to get each individual record in that result set.
You can call SqlDataAdapter.Fill passing in a DataSet. Each query result will populate a table in the DataSet:
When the query specified returns multiple results, the result set for each row returning query is placed in a separate table. Additional result sets are named by appending integral values to the specified table name (for example, "Table", "Table1", "Table2", and so on).
I think I might have figured this out. Sometimes writing the problem out helps you understand it better, and then fresh ideas start to pop up :)
I had been using the SqlDataAdapter.Fill(...) method to fill a DataTable. As it turns out, if you fill an empty DataSet it will automatically create a table for each result set returned. So, I can have a few hidden datagrids on hand and when the program detects that the DataSet filled has multiple tables, then I'll just load up each datagrid with data from each DataTable in the DataSet.