Note: this article is published on 02/21/2022.

This article was initially written in 2021, we try to make it done now. The content is mainly based on the MS article Table-Valued Parameters with some understanding and explanation, and with some examples to demo the results.

I put this article into the series of articles about SQL Tables:

Introduction

Table-valued parameters were introduced to SQL Server in 2008. Table-valued parameters provide an easy way to marshal multiple rows of data from a client application to SQL Server without requiring multiple round trips or special server-side logic for processing the data.

This is the structure of this article,

A - Passing Multiple Rows in Previous Versions of SQL Server

Before table-valued parameters were introduced to SQL Server 2008, the options for passing multiple rows of data to a stored procedure or a parameterized SQL command were limited. A developer could choose from the following options for passing multiple rows to the server:

The disadvantages of all methods above at least include one that the server side processing is necessary for them.

B - What Table-Parameters is

Table-valued parameters provide an easy way to marshal multiple rows of data from a client application to SQL Server without requiring multiple round trips or special server-side logic for processing the data. You can use table-valued parameters to encapsulate rows of data in a client application and send the data to the server in a single parameterized command. The incoming data rows are stored in a table variable that can then be operated on by using Transact-SQL.

Column values in table-valued parameters can be accessed using standard Transact-SQL SELECT statements. Table-valued parameters are strongly typed and their structure is automatically validated. The size of table-valued parameters is limited only by server memory.

There are several limitations to table-valued parameters:

C - Passing a user-defined table type to a Stored Procedure in SQL Server

1. Creating Table-Valued Parameter Types

Table-valued parameters are based on strongly typed table structures that are defined by using Transact-SQL CREATE TYPE statements. You have to create a table type and define the structure in SQL Server before you can use table-valued parameters in your client applications. We use database Northwind.

Use Northwind

CREATE TYPE dbo.CategoryTableType AS TABLE  
    ( CategoryID int, CategoryName nvarchar(50) )

In the Microsoft SQL Server Management Studio, we can see the created type:

Database->Programmability->Types->User Define Table Types:

2. Creating Stored Procedures in SQL Server using the Table-valued Parameters Type

Table-valued parameters can be used in set-based data modifications that affect multiple rows by executing a single statement.

Update

CREATE PROCEDURE usp_UpdateCategories
    (@tvpEditedCategories dbo.CategoryTableType READONLY)
AS
BEGIN
	SET NOCOUNT ON 
	UPDATE dbo.Categories  
    SET Categories.CategoryName = ec.CategoryName  
    FROM dbo.Categories INNER JOIN @tvpEditedCategories AS ec  
    ON dbo.Categories.CategoryID = ec.CategoryID; 
END

Note: that the READONLY keyword is required for declaring a table-valued parameter.

3. Run the Stored Procedure with Table-Valued Parameters (Transact-SQL)

Table-valued parameters can be used in set-based data modifications that affect multiple rows by executing a single statement.

Table Categories --- Before:

Run the Stored Procedure with Table-Valued Parameters:

DECLARE @tvpUpdateCategories AS dbo.CategoryTableType  
INSERT INTO @tvpUpdateCategories([CategoryID], [CategoryName]) VALUES(8,'SeaFood1')  
EXEC  dbo.usp_UpdateCategories @tvpUpdateCategories

Table Categories --- After

D - Passing a Table-Valued Parameter to a Stored Procedure from C# Code

We will skip this part, you may see the detailed implementation from the bottom on Table-Valued Parameters.

Note [ref]:

Normally we provide DbType of SqlParameter for a normal parameter like varchar, nvarchar, int, and so on as in the following code. 

SqlParameter sqlParam= new SqlParameter();  
sqlParam.ParameterName = "@StudentName";  
sqlParam.DbType = DbType.String;  
sqlParam.Value = StudentName;

But in the case of a Table parameter, we do not need to provide a DbType as the parameter data type. We need to provide SqlType rather than DbType, such as

SqlParameter Parameter = new SqlParameter;  
Parameter.ParameterName = "@PhoneBook";  
Parameter.SqlDbType = SqlDbType.Structured;  
Parameter.Value = PhoneTable;

Reference