How to pass an array into a Stored procedure In Ms SQL Server

How to pass an array into a stored procedure In SQL Server ?

For example, I have a list of employees. I want to use this list as a table and join it with another table. But the list of employees should be passed as parameter from C#.

SQL Server 2008 (or newer)

First, in your database, create the following two objects:

CREATE TYPE dbo.EmployeeList
AS TABLE
(
  EmployeeID INT
);
GO

CREATE PROCEDURE dbo.DoSomethingWithEmployees
  @List AS dbo.EmployeeList READONLY
AS
BEGIN
  SET NOCOUNT ON;

  SELECT EmployeeID FROM @List;
END
GO

Now in your C# code:

DataTable tvp = new DataTable();
// define / populate DataTable from your List here

using (conn)
{
    SqlCommand cmd = new SqlCommand("dbo.DoSomethingWithEmployees", conn);
    cmd.CommandType = CommandType.StoredProcedure;
    SqlParameter tvparam = cmd.Parameters.AddWithValue("@List", tvp);
    tvparam.SqlDbType = SqlDbType.Structured;
    // execute query, consume results, etc. here
}

SQL Server 2005

If you are using SQL Server 2005, I would still recommend a split function over XML. First, create a function:

CREATE FUNCTION dbo.SplitInts
(
   @List      VARCHAR(MAX),
   @Delimiter VARCHAR(255)
)
RETURNS TABLE
AS
  RETURN ( SELECT Item = CONVERT(INT, Item) FROM
      ( SELECT Item = x.i.value('(./text())[1]', 'varchar(max)')
        FROM ( SELECT [XML] = CONVERT(XML, '<i>'
        + REPLACE(@List, @Delimiter, '</i><i>') + '</i>').query('.')
          ) AS a CROSS APPLY [XML].nodes('i') AS x(i) ) AS y
      WHERE Item IS NOT NULL
  );
GO

Now your stored procedure can just be:

CREATE PROCEDURE dbo.DoSomethingWithEmployees
  @List VARCHAR(MAX)
AS
BEGIN
  SET NOCOUNT ON;

  SELECT EmployeeID = Item FROM dbo.SplitInts(@List, ',');
END
GO

And in your C# code you just have to pass the list as '1,2,3,12'...

I recommend you compare the maintainability and performance of these options against the method you selected.

Or 

Use a table-valued parameter for your stored procedure.

When you pass it in from C# you'll add the parameter with the data type of SqlDb.Structured.

Example:

// Assumes connection is an open SqlConnection object.
using (connection)
{
// Create a DataTable with the modified rows.
DataTable addedCategories =
  CategoriesDataTable.GetChanges(DataRowState.Added);

// Configure the SqlCommand and SqlParameter.
SqlCommand insertCommand = new SqlCommand(
    "usp_InsertCategories", connection);
insertCommand.CommandType = CommandType.StoredProcedure;
SqlParameter tvpParam = insertCommand.Parameters.AddWithValue(
    "@tvpNewCategories", addedCategories);
tvpParam.SqlDbType = SqlDbType.Structured;

// Execute the command.
insertCommand.ExecuteNonQuery();
}