Question

I have a general question on whether something can be done – and whether it will be the most efficient way of doing it !

To summarise: can I pass an object collection as a parameter to a stored procedure?

Let’s say that I have a SQL Server table called Users [UserID, Forename, Surname]
and another table called Hobbies [HobbyID, UserID, HobbyName, HobbyTypeID]

This set up is to record multiple hobbies against a user.

In my application, I want to update the user record.

Normally – I would update the user table and then in code, loop through each hobby and update the hobbies table record by record.

If I’m updating the user forename and 2 of their hobbies, this would require 3 calls to the database.

(1 call to a stored procedure to update the forename/surname, and 2 calls to a stored procedure to update the 2 hobby records)

My question is:
Can I make just 1 call to the database by passing all the parameters to just 1 stored procedure.

eg.

intUserID = 1
strForename = "Edward"
strSurname = "ScissorHands"

dim objHobbyCollection as New List(Of Hobby)
'Assume that I have 2 hobby objects, each with their hobbyID, UserID, HobbyName & HobbyTypeID

Dim params As SqlParameter()
params = New SqlParameter() {
    New SqlParameter("@UserID", intUserID),
    New SqlParameter("@Forename", strForename),
    New SqlParameter("@Surname", strSurname),
    New SqlParameter("@Hobbies", objHobbyCollection) 
    }

Can I do this ? (and which way would be more efficient?)
What would the Stored Procedure look like ?

ALTER PROCEDURE [dbo].[User_Update]

 @UserID    INT
,@Forename      NVARCHAR(50) = NULL
,@Surname   NVARCHAR(50) = NULL
,@Hobbies   ??????????????

Answer 1

Assuming SQL Server 2008+, you can do this using a table-valued parameter. First in SQL Server create a table type:

CREATE TYPE dbo.HobbiesTVP AS TABLE
(
  HobbyID INT PRIMARY KEY,
  HobbyName NVARCHAR(50),
  HobbyTypeID INT
);

Then your stored procedure would say:

@Hobbies dbo.HobbiesTVP READONLY

In C# (sorry I don’t know vb.net equivalent) it would be as follows (but if you just have one UserID, this doesn’t need to be part of the collection, does it?):

// as Steve pointed out, you may need to have your hobbies in a DataTable.

DataTable HobbyDataTable = new DataTable();
HobbyDataTable.Columns.Add(new DataColumn("HobbyID"));
HobbyDataTable.Columns.Add(new DataColumn("HobbyName"));
HobbyDataTable.Columns.Add(new DataColumn("HobbyTypeID"));

// loop through objHobbyCollection and add the values to the DataTable,
// or just populate this DataTable in the first place

using (connObject)
{
    SqlCommand cmd = new SqlCommand("dbo.User_Update", connObject);
    cmd.CommandType = CommandType.StoredProcedure;
    // other params, e.g. @UserID
    SqlParameter tvparam = cmd.Parameters.AddWithValue("@Hobbies", HobbyDataTable);
    tvparam.SqlDbType = SqlDbType.Structured;
    // ...presumably ExecuteNonQuery()
}