Inserting Multiple Rows in SQL Server via Table Valued Parameters

26. February 2014 11:40 by Parakh in ASP.NET, SQL Server  //  Tags: , ,   //   Comments
This post covers how can we insert multiple rows worth of data via table valued parameters in SQL Server database.

Key take away:

In my last posts, I have described ways to insert multiple rows worth of data in a SQL Server database via a Comma Separated List and XML. In this post I will describe how to insert multiple rows from a .Net application using the most preferred way, a native feature in SQL Server, Table Valued Parameters.

Read on:

A short introduction to Table Valued Parameters:

Parameters are place holder for values that are passed from various constructs outside of a programming artifact. We declare parameters all the time, in various technologies, and in various forms - command line arguments, query string values in ASP.NET, sql parameters that carry information to database in a type safe way, etc. In SQL Server parameters are the way to pass and receive information that needs to be dealt with, and information can come from either within SQL Server or outside of SQL Server like from a .Net application. Parameters are generally made of a primal data type like int, char, varchar etc. When such parameters are modeled on some pre-defined table type, such parameters are called Table Valued Parameters. The important words to note here are “table type”. Not table, but table type, which means a user defined type based on some table structure.

Table Valued Parameters have been supported by SQL Server since version 2008.

To demonstrate the concept of TVPs, I will be using a very simple data model consisting of three tables: Student, Course and an association table supporting many-to-many relationship between Student and Course, StudentCourse.

The Entity-Relationship diagram will clarify the relationship between the tables:

ERD diagram:

ERD diagram

 

 

 

 

 

 

 

According the ER diagram, a student can take many courses and a course can be taken by many students. The insertion of courses that a student is interested in the association table is an ideal application of this technique.

Now consider the following code to make a table type. this type will be used to model a table valued parameter on the table type:

   1:  CREATE TYPE StudentCoursesTableType AS Table
   2:  ([StudentID] [int] NULL,
   3:   [CourseID] [int] NULL);

 

Making a table type makes the type available in the User-Defined Table Types sub-section of Types section.

clip_image002

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Execution of the following code should give you some result depending on what you have available in the StudentCourse table.

   1:  Declare @StudentCoursesTVP as StudentCoursesTableType;
   2:   
   3:  Insert into @StudentCoursesTVP(StudentID, CourseID)
   4:  Select [StudentID], [CourseID] from [dbo].[StudentCourse];
   5:   
   6:  Select * from @StudentCoursesTVP;
 
 

clip_image002[5]

 

 

 

 

 

 

 

 

 

 

 

So now that we are through with the basics of TVP, let’s see how we can use them in our main purpose of processing multiple rows of data. To demonstrate this, I will be using a simple web form application powered by the same data model discussed above. The application helps a student get enroll in the course(s) of his/her choice.

clip_image004

 

 

 

 

 

 

 

 

 

 

 

 

The coding for the webpage is very simple. The pseudo-code is as follows:

1. Select a student from the drop down.

2. Select from the available courses that the student needs enrollment for.

3. Click on the submit button.

I am going to leave it up to the reader to understand the programming in the web application. It is straight forward and the domain model powering the application is a reflection of the data model depicted above.

The main work is being done at two places:

1. Web application’s repository method which parses the incoming object data into a datatable.

2. The stored procedure responsible for receiving the data in the form of a table valued parameter and using it to feed data into the desired table.

Consider the following repository method in the StudentSQLRepository class:

   1:  public int GetEnrolled(List<Course> courses, int studentID)
   2:          {
   3:              DataTable table = new DataTable("data");
   4:              table.Columns.Add("StudentID");
   5:              table.Columns.Add("CourseID");
   6:              foreach (Course course in courses)
   7:              {
   8:                  table.Rows.Add(new object[] { studentID, course.CourseID});
   9:              }
  10:              string sql = @"dbo.EnrollStudentInCourses";
  11:              int result = 0;
  12:              SqlParameter studentCoursesTVP = new SqlParameter("StudentCoursesTVP", table);
  13:              studentCoursesTVP.SqlDbType = SqlDbType.Structured;
  14:              using (SqlConnection connection = new SqlConnection(connectionString))
  15:              {
  16:                  using (SqlCommand command = new SqlCommand(sql, connection))
  17:                  {
  18:                      command.CommandType = CommandType.StoredProcedure;
  19:                      command.Parameters.Add(studentCoursesTVP);
  20:   
  21:                      connection.Open();
  22:                      result = command.ExecuteNonQuery();
  23:                      connection.Close();
  24:                  }
  25:              }
  26:              return result;
  27:          }

There are two noteworthy points in the code above:

1. We are passing the datatable to the SQL Server database to be processed. The datatable is modeled on the table type present in the SQL Server database, used by the table valued parameter.

2. The SqlDbtype of the SqlParameter is set to Structured type. This is strictly done to improve the readability of our code and convey meaning in an explicit way. ADO.NET will perfectly parse the datatable correctly had we not declared the SqlDbType to Structured explicitly.

Following is the SQL script of the dbo.EnrollStudentInCourses responsible for parsing the data in the @StudentCoursesTVP table valued parameter correctly.

   1:  CREATE PROCEDURE [dbo].[EnrollStudentInCourses]
   2:      
   3:      @StudentCoursesTVP StudentCoursesTableType readonly
   4:   
   5:  AS
   6:  BEGIN
   7:   
   8:      Insert into StudentCourse (StudentID, CourseID)
   9:      Select StudentID, CourseID from @StudentCoursesTVP    
  10:      
  11:  END
  12:   
  13:  GO

 

If you go and read my two other posts on inserting multiple rows using a comma separated values list and XML, you surely will come to the conclusion that using table valued parameters is the cleanest approach, that doesn’t include any code acrobatics either in .Net code or in SQL code. Not only that, table valued parameters code is highly performant as long as there’s reasonable data involved.

The sample code for this post can be downloaded from the following location:

References:

1. Table Valued Parameters at TechNet

Inserting Multiple Rows in SQL Server via a XML

15. February 2014 12:33 by Parakh in SQL Server, XML  //  Tags: , , ,   //   Comments
This post discusses how to post multiple rows worth of data to a SQL Server database using XML to minimize calls made to the database to store data.

Key take away:

My last two posts touched on the two methods available in SQL Server to flatten hierarchical XML data into flat relational form. In this post I will build upon those concepts and will cover how to leverage them to insert multiple rows worth of data into a SQL Server database in a single call.

Read on:

Hierarchical XML data can be flattened at SQL Server database level using one of the two ways:

1. OPENXML method

2. Nodes method

One of the reason why we would want to convert XML data into relational data at database level is to push in multiple rows worth of data to be inserted into a single or multiple tables in a single database call. Opening and closing a connection to a database for doing operation can be a costly affair for a website storing a sizeable amount of data at every call. The cost can be minimized by sending all the related data in a single call and parsing it out into distinct rowsets and storing them in the desired table(s). This scenario is especially true when you provide editing capabilities in a tabular or gridview kind of an environment and allow user to check in all the changes in one button click.

The technique of storing multiple rows with the help of XML works on the following strategy:

1. Convert the information into XML hierarchy.

2. Pass the XML to SQL Server.

3. Parse the hierarchy via one of the methods – OPENXML or nodes method and convert it into relational form.

4. Parse the relational form and store it via normal insert query.

To demonstrate I will be using a very simple data model consisting of three tables: Student, Course and an association table supporting many-to-many relationship between Student and Course, StudentCourse.

The Entity-Relationship diagram will clarify the relationship between the tables:

ERD diagram

 

 

 

 

 

 

 

According the ER diagram, a student can take many courses and a course can be taken by many students. The insertion of courses that a student is interested in the association table is an ideal application of this technique.

The following ASP.NET webform that is the web front end that we will use to form a complete example to demonstrate this approach:

image

 

 

 

 

 

 

 

 

 

 

 

 

The coding for the webpage is very simple. The pseudo-code is as follows:

1. Select a student from the drop down.

2. Select from the available courses that the student needs enrollment for.

3. Click on the submit button.

I am going to leave it up to the reader to understand the programming in the web application. It is straight forward and the domain model powering the application is a reflection of the data model depicted above.

The main work is being done at two places:

1. Web application’s repository method which does the work of making a hierarchical XML data from the objects.

2. The stored procedure that converts incoming XML data into relational data and stores it into table.

Consider the following repository method:

   1:  public int GetEnrolled(List<Course> courses, int studentID)
   2:          {
   3:              DataTable table = new DataTable("data");
   4:              table.Columns.Add("StudentID");
   5:              table.Columns.Add("CourseID");
   6:   
   7:              foreach (Course course in courses)
   8:              {
   9:                  table.Rows.Add(new object[] { studentID, course.CourseID});
  10:              }
  11:   
  12:              string data;
  13:              using (StringWriter sw = new StringWriter())
  14:              {
  15:                  table.WriteXml(sw);
  16:                  data = sw.ToString();
  17:              }
  18:   
  19:   
  20:              string sql = @"dbo.EnrollStudentInCourses";
  21:   
  22:              int result = 0;
  23:   
  24:              SqlParameter xml = new SqlParameter("XML", data);
  25:   
  26:              using (SqlConnection connection = new SqlConnection(connectionString))
  27:              {
  28:                  using (SqlCommand command = new SqlCommand(sql, connection))
  29:                  {
  30:                      command.CommandType = CommandType.StoredProcedure;
  31:                      command.Parameters.Add(xml);
  32:   
  33:                      connection.Open();
  34:                      result = command.ExecuteNonQuery();
  35:                      connection.Close();
  36:                  }
  37:              }
  38:   
  39:              return result;
  40:          }

 

The point of interest in the code mentioned above are the lines that push the object data into a datatable and the code that converts the datatable into an XML hierarchy. Please note that the hierarchy will include the name of the datatable that gets set in the .Net code. So please name it appropriately. The resulting XML hierarchy looks something as shown below:

   1:  <DocumentElement>
   2:      <data>
   3:          <StudentID>1</StudentID>
   4:          <CourseID>4</CourseID>
   5:      </data>
   6:      <data>
   7:          <StudentID>1</StudentID>
   8:          <CourseID>5</CourseID>
   9:      </data>
  10:      <data>
  11:          <StudentID>1</StudentID>
  12:          <CourseID>6</CourseID>
  13:      </data>
  14:  </DocumentElement>

It is this XML that gets passed to the SQL Server and is de-serialized into relational form using the nodes method. I have discussed the fundamentals of the nodes method in my last post. The de-serialization can also be carried out by using the OPENXML method.

The core of the dbo.EnrollStudentInCourses stored procedure, responsible for recording the course enrollment data for a student is made of the following code:

   1:  Insert into StudentCourse (StudentID, CourseID)
   2:  SELECT
   3:  data.value('(StudentID/text())[1]','int') as StudentID,
   4:  data.value('(CourseID/text())[1]','int') as CourseID
   5:  FROM @XML.nodes('/DocumentElement/data')
   6:  as StudentCourses(data)
 

NOTE: The SQL code is made keeping in mind the name of the datatable used to capture the data in the .Net code.

The sample code for this post consists of the web application and the powering database. Download it from:

Inserting Multiple Rows in SQL Server via a Comma Separated Values List

29. September 2013 09:59 by Parakh in SQL Server, ASP.NET  //  Tags: , , , ,   //   Comments
There are three approaches to key in multiple rows into a single table in SQL Server database. One of them is comma separated list, discussed in this post.

 

Key takeaway:

Frequently there are scenarios here you might be required to key in multiple rows into a SQL Server database table. In order to do that with minimum number of calls and a low memory footprint, there are several approaches available. I know of three, of which I am presenting the comma separated values (CSV) list approach.

Read on:

A few days ago, I ran into a requirement that required me to insert multiple rows of data into a table in a SQL Server database. There are a couple of approaches to do this and I am planning to do a series on this. Some of the approaches to do this are the following:

1. Passing a comma separated value (CSV) list to the database and parsing it at the database level with the help of a user defined function to split the list into rows and inserting those rows.

2. Passing the data as XML hierarchy,

3. Using Table Valued Functions, a feature that SQL Server supports version 2008 onwards.

All the three approaches are valid approaches and usage depends upon the kind of constraints that you are operating with. I was dealing with a legacy codebase, that did not afforded me the luxury of table valued parameters, which is the most straight forward and efficient way of accomplishing this, and had to settle for the CSV list and eventually the XML way.

In this post I will be covering the CSV list method. The comma separated values list method requires the following main ingredient: a user defined function that can be used to split text on the defined delimiter. Since this post is all about demonstrating the comma separated values list approach, I will not delve into the internal mechanics of such function. I just grabbed the first function that I could get off of the internet, and made it work.

I got the split function from the following url: SQL Server Forums - Best split function courtesy of the member Corey alias Seventhnight.

The technique works on the following strategy:

1. Parse the information that needs to be stored in the database in the form of a CSV list.

2. Pass it to the database packed in an appropriate type of parameter.

3. De-serialize the information into a table variable with the help of the aforementioned splitter function.

4. Depending upon the total number of columns in the target table, run a combination of insert and update commands, fetching the information from the table variable. A combination is made this way in order to minimize the disk activity, and complete the operation in as short duration as possible.

To demonstrate I will be using a very simple data model consisting of three tables: Student, Course and an association table supporting many-to-many relationship between Student and Course, StudentCourse. The Entity-Relationship diagram will clarify the relationship between the tables:

clip_image002

 

 

 

 

 

 

 

According the ER diagram, a student can take many courses and a course can be taken by many students. The insertion of courses that a student is interested in the association table is an ideal application of this technique.

The following ASP.NET webform that is the web front end that we will use to form a complete example to demonstrate this approach:

clip_image004

 

 

 

 

 

 

 

 

 

 

 

The coding for the webpage is very simple. The pseudo-code is as follows:

1. Select a student from the drop down.

2. Select from the available courses that the student needs enrollment for.

3. Click on the submit button.

I am going to leave it up to the reader to understand the programming in the web application. It is straight forward and the domain model powering the application is a reflection of the data model depicted above.

All the magic happens in the stored procedure powering the enrollment of a student in one of the listed courses. The stored procedure is as follows:

   1:  CREATE PROCEDURE [dbo].[EnrollStudentInCourses]
   2:   
   3:  @StudentID int,
   4:   
   5:  @Courses nvarchar(max)
   6:   
   7:  AS
   8:   
   9:  BEGIN
  10:   
  11:  Declare @TempStudentCourseTable Table
  12:   
  13:  (
  14:   
  15:  StudentID int null,
  16:   
  17:  CourseID int null
  18:   
  19:  );
  20:   
  21:  Insert into @TempStudentCourseTable (CourseID)
  22:   
  23:  Select CONVERT(int,Data) from dbo.Split(@Courses,',');
  24:   
  25:  Update @TempStudentCourseTable Set StudentID = @StudentID;
  26:   
  27:  Insert into dbo.StudentCourse (StudentID,CourseID)
  28:   
  29:  Select StudentID,CourseID from @TempStudentCourseTable;
  30:   
  31:  END
  32:   
  33:  GO
  34:   

 

The pseudo-code for the stored procedure is as follows:

1. There are two parameters in the stored procedure – The student ID of the student, who needs to be enrolled, and the courses passed as an nvarchar(max) parameter representing a CSV list of the courses in which the enrollment needs to be done.

2. The procedure uses a table variable that mimics the table structure of the StudentCourse table, sans the primary key.

3. Insert command is carried out on the table variable, with the CSV list comprised of the courses passed to the splitter function. Since out splitter function returns a table, with two columns – ID (int type identity column), and Data (nvarchar type), we can right away leverage the Data field, and insert it into the table variable by carrying out required conversion on the fly. Here I am converting the Data to integer, since CourseID is of type int.

4. Once the insertion has been done, I update the StudentID field in the table variable with the passed parameter value.

5. Once this is complete, I ran the Insert…Select… command to key in data into the final StudentCourse table. Depending upon the settings in the database, this will be a minimally logged operation, thereby giving you speed benefits.

Note that this is an overly simple example of the stored procedure, not employing transaction, error handling etc. and is meant to convey the concept of usage of comma separated values list in inserting multiple rows.

Emerging pattern:

If you look at this and carry it forward to more complicated use cases, then you’ll see a pattern emerging out. The pattern is:

1. Model the table variable after the final table that is supposed to receive the data.

2. Insert the most variable information in the table variable first.

3. Follow up the insertion with updation of table variable with information that is not changing much, like the StudentID in this example. It remains constant for all the courses inserted into the table variable.

4. If you need selective action within the table variable, make use of an integer type identity column. In this example, we did not require that.

5. The complexity of the procedure will depend upon the total columns in the final table. The more the columns, the more the number of update commands. There will also be a loop that you will have to manage in order to update the table variable with the right row form the table emitted by the splitter function.

In the next post I will cover how to insert multiple rows in SQL Server database using XML.

The sample code for this post consists of the web application and the powering database. Download it from:

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