Object we can contain multiple DataTable objects in a dataset.
DataSet myDataSet = new DataSet ();
DataTable TableA = new DataTable ("A");
DataTable TableB = new DataTable ("B");
MYDATASET.TABLES.ADD (TableA);
MYDATASET.TABLES.ADD (TableB);
This includes a TableA and a TableB two DataTable objects in the myDataSet, and we access the DataTable contained in the
1. First locate your project in Solution Explorer, right-click and choose Add Class.2. after naming the class, double-click to open it. I'm named SqlHelper here.Add the following statement in the upper row using the following line:Using System.Data;Using System.Data.SqlClient;Using System.Net;These are the files that must be called to call the DataSet method and the database connection method.public class SqlHelper{public static
Asp tutorial. net dataset, able, and dateviewAtaset is a temporary small warehouse. Through sqldataapert, it can be equivalent to a truck, and data is stored in dataset through the adapter sqldataapert in the database tutorial. Even if the connection is disconnected, it can still deal with the database, the following is an example:
Public static dataset query (st
Using system;Using system. Data;Using system. xml;
//************************************** *// Prepared by: # go to dinner tomorrow// Qicq: 305725744//. Net group: 6370988//Http://blog.csdn.net/kgdiwss//************************************** *
Namespace dataset2xml. Component{/// /// Operatexmlbydataset abstract description./// Public class operatexmlbydataset{Public operatexmlbydataset (){//// Todo: add the constructor logic here//}# Region getdatasetbyxml/// /// Read XML and return
WebServices is used in recent projects. The WebServices method is called and sqldatareader cannot be returned. The following message is displayed: sqldatareader cannot be serialized,Dataset is okay, of course... one of them is that when sqldatareader is used, Conn should be connected...
However, sometimes using dataset is a waste of resources, so I reprinted this article.Article:
For more information
I have tested the dataset new "binary serialize" feature in ADO. net2.0. Except articals said if we set the dataset's property"Remotingformat" as "serializationformat. Binary", it can serializeItself in binary format.
OK, this propety works well, the output file is much smaller than XML style.
But I got something strange:IfI first set a dataset "remotingformat" as "binary" before serialize itInto a file
Define the column field name of the dataset by yourself: Create a class and inherit the dataset class. add custom columns to the dataset in advance. There are two advantages:
1. directly reference: Dataset. table [0]. row [0] [customer. name]; not: Dataset. table [0]. row [
Basic Ideas
The reflection mechanism is used to assign values to each other for the DataTable fields and custom public attributes. NOTE: For the conversion from DataSet to IList
Code Description
/// /// The generic set and DataSet convert each other/// Public class IListDataSet{
/// /// Set for DataSet/// /// /// // HPDV2806Public static
Asp.net how to convert DataSet to josn and output the datasetjosn
public class JsonUtil { public string ToJson(DataSet dataSet) { string jsonString = "{"; foreach (DataTable table in dataSet.Tables) { jsonString += """" + table.TableName + """:" + ToJson(table) + ","; } jsonString = jsonString.TrimEnd(','); return jsonString + "}"; } public string ToJson(DataTabl
1. Climate Monitoring Data Set http://cdiac.ornl.gov/ftp/ndp026b
2. Some useful websites for downloading test Datasets
Http://www.cs.toronto.edu /~ Roweis/data.htmlHttp://www.cs.toronto.edu /~ Roweis/data.htmlHttp://kdd.ics.uci.edu/summary.task.type.htmlHttp://www-2.cs.cmu.edu/afs/cs.cmu.edu/project/theo-20/www/data/Http://www-2.cs.cmu.edu/afs/cs.cmu.edu/project/theo-11/www/wwkb/Http://www.phys.uni.torun.pl /~ Duch/software.htmlYou can find the Reuters datas
Dataset to ilistCode:
///
,
///
Replace dataset with a generic set
///
///
///
Dataset
///
Index of the data table to be converted
///
Public
Static Ilist Int Tableindex)
{
If (DS =
Null | Ds. Tables. Count 0 )
Return
Null ;
If (Tableindex> DS. Tables. Count-
1 )
R
C # Performance Tuning details
1. Use ItemArray to realize batch assignment of DataRow
When assigning values to all fields of a DataRow, using field names for column-wise assignment is less efficient. You should use bulk field assignments whenever possible. You can use the ItemArray or Rows.Add method:/DS is a DataSet (DataSet) object datatable dt = ds. Tables[0];D atarow row = dt. NewRow (); row. I
1. sqldataread and dataset Selection
Sqldataread advantages: fast data reading. If you do not need to process the returned data in large quantities, we recommend that you use SqlDataReader. Its performance is much better than that of datset. Disadvantage: the connection to the database cannot be closed until the data is read.
(SqlDataReader reads data quickly forward. SqlDataReaderClass provides a method to read data streams only retrieved from the SQ
From: http://www.cnblogs.com/joaen/archive/2005/07/01/184776.html
XML reading is always done through the readxml method of dataset, and other attributes are not used. When the data volume is small, it is still safe. It is not until today that a 20 m XML Stream is read that it affects efficiency.
By default, the xmlreadmode. Auto method is used to read readxml by default. The previous method is used because the XML file does not containScheme
The requirement is as follows: I have a dataset with a able, which is a dataset generated based on different parameters in the calling stored procedure, and its columns are variable. Now we need to make a simple report for such a dataset.
You cannot design a fixed rdlc report file for the able of a variable column, because column is dynamic, it may be two column
If the SQL statement is executed directly, the transaction is well processed. For most ERP applications, SQL cannot be used to process data. Therefore, it is more common to update dataset and update a single dataset, no transaction processing is required. To add transactions to multiple dataset, most of them are applied to distributed
Program
Code The followin
Sometimes we often need to import datasets into the database. What should we do? Some people have said that SQL statements can be used to solve the problem right away. Yes, SQL statements can be used to solve the problem. However, SQL concatenation cannot cause errors. Using sqlparameter can reduce the type troubles, however, if there are many columns, you will not be exhausted.
1. Import dataset to access (Oledbdataadapter. UpdateMethod)
Oledbcon
C # dataset index No Value SolutionReplyWhen datsset is bound to the datagrieview, when the dataset data is refreshed, the bug is often found: index 0 has no value or index (INT) X has no value indexoutofrangeexception.I made an afternoon yesterday and found the cause of the bug:When data exists in the dview, the first row is selected by default. When we clear the data in the
http://blog.sina.com.cn/jiangshuqin2010
1,if (ds = = null) This is to determine if the data set in memory is empty, the dataset is empty, the rows and columns do not exist!!
2,if (ds. Tables[0]. Count = = 0) This should be a dataset in memory, but there is no table in the DataSet!!
3,if (ds. Tables[0]. Count = = 1 ds. Tables[0]. Rows.Count = = 0) indicates
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