How does DataReader work in C#?
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How does DataReader work in C#?
C# DataReader class represents a data reader. The DataReader provides a read-only, forward-only mechanism to access data via ADO.NET from a datasource….Initializing DataReader
- SqlCommand cmd = new SqlCommand(SQL, conn);
- // Call ExecuteReader to return a DataReader.
- SqlDataReader reader = cmd. ExecuteReader();
What is SQL DataReader?
The ADO.NET SqlDataReader class in C# is used to read data from the SQL Server database in the most efficient manner. It reads data in the forward-only direction. It means, once it read a record, it will then read the next record, there is no way to go back and read the previous record.
How do I get data from ExecuteReader?
To retrieve data using a DataReader, create an instance of the Command object, and then create a DataReader by calling Command. ExecuteReader to retrieve rows from a data source.
What’s better DataSet or DataReader?
DataReader provides faster performance, but has read-only and forward-only access. DataSet, on the other hand, is high resource-consuming, but offers more control and a disconnected nature.
What is the role of SqlCommand class?
SqlCommand Class The main role of SqlCommand is to execute SQL statements.
What is DataReader and DataAdapter?
DataAdapter is an intermediate layer/ middleware which acts a bridge between the DataSet and a Database whereas DataReader provides forward-only, read-only access to data using a server-side cursor (simply put it is ued to read the data).
Does SqlCommand need to be disposed?
The component class (which remember the SqlCommand indirectly inherits from), implements such a Dispose method. Therefore to prevent the finalizer from running (and even though it does nothing in the case of SqlCommand), you should always call Dispose.
Why do I have to call read to open a sqldatareader?
Therefore, you must call Read to begin accessing any data. Only one SqlDataReader per associated SqlConnection may be open at a time, and any attempt to open another will fail until the first one is closed. Similarly, while the SqlDataReader is being used, the associated SqlConnection is busy serving it until you call Close.
How do I iterate through the results of a sqldatareader?
If the DataReader returns multiple result sets, call the NextResult method to iterate through the result sets sequentially. The following example shows the SqlDataReader processing the results of two SELECT statements using the ExecuteReader method.
What is the default position of the sqldatareader?
The default position of the SqlDataReader is before the first record. Therefore, you must call Read to begin accessing any data. Only one SqlDataReader per associated SqlConnection may be open at a time, and any attempt to open another will fail until the first one is closed.
