In this article, I described how to pass a table to a function parameter in SQL Server. In this article, you create a table, student, then create a user-defined table type and pass the table type as a parameter to a function. So let's have a look at a practical example of how to pass a table as a function parameter in SQL Server. The example is developed in SQL Server 2012 using the SQL Server Management Studio.
Here is how to implement passing a user-defined table type to a function.

1. Create a Student Table in SQL Server

Create a table named Student.
  1. CREATE TABLE [dbo].[Student]
  2. (
  3. [StudentID] [int] NULL,
  4. [StudentName] [varchar](30) NULL,
  5. [StudentFees] [int] NULL
  6. )

2. Create a User-Defined Table Type in SQL Server

Now create a user-defined table type to be used as a table-valued parameter in the function.
  1. CREATE TYPE dbo.StudentType AS TABLE
  2. (
  3. [StudentID] [int] ,
  4. [StudentName] [varchar](30) ,
  5. [StudentFees] [int]
  6. )
Now Press F8 to see the created type in the Object Explorer.
Database->Programmability->Types->User Define Table Types
User-Defined Table Type in SQL Server

3. Creating a Function in SQL Server

Now create the StudentDetailFunctionFunction. This function will accept a table-valued parameter.
READONLY keyword - This keyword is required to declare a table-valued parameter.
  1. ALTER FUNCTION StudentDetailFunction( @StudentDetail dbo.StudentType READONLY )
  2. RETURNS VARCHAR(50)
  3. AS
  4. BEGIN
  5. DECLARE @Studentname VARCHAR(50)
  6. SELECT @Studentname= StudentName FROM @StudentDetail
  7. RETURN @Studentname
  8. END

4. Execute the SQL Server Function

Now you can declare a variable @StudentVariable which contains the value of the table columns.
  1. DECLARE @StudentVariable AS StudentType
  2. INSERT INTO @StudentVariable(StudentName) VALUES('Rohatash')
  3. SELECT dbo.StudentDetailFunction(@StudentVariable)
Output
Execute SQL Server Function