Retrieving Database Records v4.1.6.1
You can use a SELECT
statement to retrieve records from the database via a SELECT
command. To execute a SELECT
statement you must:
- Create and open a database connection.
- Create an
EDBCommand
object that represents theSELECT
statement. - Execute the command with the
ExecuteReader()
method of theEDBCommand
object returning aEDBDataReader
- Loop through the
EDBDataReader
displaying the results or binding theEDBDataReader
to some control.
An EDBDataReader
object represents a forward-only and read-only stream of database records, presented one record at a time. To view a subsequent record in the stream, you must call the Read()
method of the EDBDataReader
object.
The example that follows:
- Imports the Advanced Server namespace:
EnterpriseDB.EDBClient
- Initializes an
EDBCommand
object with aSELECT
statement. - Opens a connection to the database.
- Executes the
EDBCommand
by calling theExecuteReader
method of theEDBCommand
object.
The results of the SQL statement are retrieved into an EDBDataReader
object.
Loops through the contents of the EDBDataReader
object to display the records returned by the query within a WHILE
loop.
The Read()
method advances to the next record (if a record exists) and returns true
if a record exists, or false
to indicate that the EDBDataReader
has reached the end of the result set.
To exercise the sample code, save the code in your default web root directory in a file named:
selectEmployees.aspx
To invoke the program, open a web-browser, and browse to:
http://localhost/selectEmployees.aspx
Retrieving a Single Database Record
To retrieve a single result from a query, use the ExecuteScalar()
method of the EDBCommand
object. The ExecuteScalar()
method returns the first value of the first column of the first row of the DataSet
generated by the specified query.
Save the sample code in a file in a web root directory named:
selectscalar.aspx
To invoke the sample code, open a web-browser, and browse to:
http://localhost/selectScalar.aspx
Please note that the sample includes an explicit conversion of the value returned by the ExecuteScalar()
method. The ExecuteScalar()
method returns an object; to view the object, you must convert it into an integer value by using the Convert.ToInt32
method.
- On this page
- Retrieving a Single Database Record