Stored Procedures are a set of sql commands which are compiled and are stored inside the database. Every time you execute a sql command, the command is parsed, optimization is done and then the command is executed. Parsing and optimization the command each time you run the query is very expensive. To solve this we have a set of commands collectively called as stored procedure, which are already parsed and optimized and are executed when ever we call them. This article describes about how to call the stored procedures through Ado.net and how to handle the output parameters of the called stored procedures.
Initially create a object of SqlConnection class which is available in System.Data.SqlClient namespace. You has to provide the connection string as a parameter which includes the Data Source name, the database name and the authentication credentials. Open the connection using the Open() method.
SqlConnection con = new SqlConnection("Data Source= ; initial catalog= Northwind ; User Id= ; Password= '");
Create the following stored procedure on the Region table in the Northwind database which accepts two parameters and does not have any output parameters.
CREATE PROCEDURE RegionUpdate (@RegionID INTEGER,
@RegionDescription NCHAR(50)) AS
SET NOCOUNT OFF
SET RegionDescription = @RegionDescription
Create a SqlCommand object with the parameters as the name of the stored procedure that is to be executed and the connection object con to which the command is to be sent for execution.
SqlCommand command = new SqlCommand("RegionUpdate",con);
Change the command objects CommandType property to stored procedure.
command.CommandType = CommandType.StoredProcedure;
Add the parameters to the command object using the Parameters collection and the SqlParameter class.
Specify the values of the parameters using the Value property of the parameters
Excecute the stored procedure using the ExecuteNonQuery method which returns the number of rows effected by the stored procedure.
Now let us see how to execute stored procedures which has output parameters and how to access the results using the output parameters.
Create the following stored procedure which has one output parameter.
ALTER PROCEDURE RegionFind(@RegionDescription NCHAR(50) OUTPUT,
@RegionID INTEGER )AS
SELECT @RegionDescription =RegionDescription from Region where <A href="mailto:RegionID=@RegionID">RegionID=@RegionID</A>
The above stored procedure accepts regionID as input parameter and finds the RegionDescription for the RegionID input and results it as the output parameter.
SqlCommand command1 = new SqlCommand("RegionFind",con);
command1.CommandType = CommandType.StoredProcedure;
Add the paremeters to the command1
command1.Parameters.Add(new SqlParameter ("@RegionDescription",SqlDbType.NChar ,50,ParameterDirection.Output,false,0,50,"RegionDescription",DataRowVersion.Default,null));
command1.Parameters.Add(new SqlParameter("@RegionID" ,
Observe that the parameter RegionDescription is added with the ParameterDirection as Ouput.
specify the value for the input parameter RegionID.
command1.Parameters["@RegionID"].Value = 4;
Assign the UpdatedRowSource property of the SqlCommand object to UpdateRowSource.OutputParameters to indicate that data will be returned from this stored procedure via output parameters.
command1.UpdatedRowSource = UpdateRowSource.OutputParameters;
Call the stored procedure and access the RegionDescription for the RegionID 4 using the value property of the parameter.
string newRegionDescription =(string) command1.Parameters["@RegionDescription"].Value;
Close the sql connection.
In the same way you can call the stored procedure that returns a set of rows by defining the parameters as appropriate and executing the command using ExecuteReader() that is used to traverse the records returned by the command.