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Calling SQL Server Stored Procedures with ADO.NET in 5 minutes

Bali — Sun, 02 Aug 2009 02:35:01 +0000

A stored procedure is an already written SQL statement that is saved in the database. It can take parameters; return objects you specified, just like what happens in any other programming languages you are familiar with.

Why stored procedures instead of random SQL? For me:

1. Modular Programming- Stored procedures allow developers to encapsulate business functionality and provide callers with a simple interface. Once interfaces are settled down, caller and callee coding work can be assigned to different team/persons.

2. Security Enhancement- Users can be granted permission to execute a stored procedure. Use parameterized queries—not string concatenation—to build queries.

3. Reduce network traffic – Benefits can be easily noticed if you have frequently called T-SQL code of hundreds of lines.

4. Performance – Stored procedures are registered at servers, and as a result DBAs/servers get more change to optimize them.

Coding time now. Firstly, you need run below SQL script in SQL2005.

SQL Script

– Create a test DB

USE [master]

CREATE DATABASE SpTestDB

USE SpTestDB

– Create a test Table

CREATE TABLE dbo.TestTable (

id [nvarchar](50) NULL,

SomeValue [int] NULL

)

– Create read SP

CREATE PROCEDURE dbo.ReadData

@id nvarchar (50)

BEGIN

SELECT * FROM dbo.TestTable

WHERE id = @id;

END

– Create write SP

CREATE PROCEDURE dbo.WriteData

@id nvarchar (50),

@SomeValue int

BEGIN

INSERT INTO dbo.TestTable (id, SomeValue)

VALUES (@id, @SomeValue);

END

Next, you can call in ADO.NET.

ADO.NET C# code

using System;

using System.Collections.Generic;

using System.Text;

using System.Data.SqlClient;

namespace ConsoleApplication4

{

class Program

{

// NOTICE: You MUST replace ‘localhost\baligoal’ with your own DB instance name

const string ConnString = @”Data Source=localhost\baligoal;Initial Catalog=SpTestDB;Integrated Security=True”;

///

/// Write a record to DB with stored procedure “WriteData”,

/// and then read it out with stored procedure “ReadData”

///

static void Main(string[] args)

{

const string TestID = “firstid”;

const int TestValue = 500;

// Firstly, write a record with store procedure

using (SqlConnection conn = new SqlConnection(ConnString))

{

// Specify ‘WriteData’ procedure in the params

using (SqlCommand cmd = new SqlCommand(“WriteData”, conn))

{

cmd.CommandType = System.Data.CommandType.StoredProcedure;

// The param names are exactly the same with SP WriteData’s

cmd.Parameters.AddWithValue(“@id”, TestID);

cmd.Parameters.AddWithValue(“@SomeValue”, TestValue);

cmd.Connection.Open();

cmd.ExecuteNonQuery();

}

// If you set BP here, and check you DB table, you should find ‘firstid, 500′ there

Console.WriteLine(“Write: done.”);

// Next, read it out with store procedure

using (SqlConnection conn = new SqlConnection(ConnString)) {

// Specify ‘ReadData’ procedure in the params

using (SqlCommand cmd = new SqlCommand(“ReadData”, conn)) {

cmd.CommandType = System.Data.CommandType.StoredProcedure;

// The param names is exactly the same with SP ReadData’s

cmd.Parameters.AddWithValue(“@id”, TestID);

cmd.Connection.Open();

using (SqlDataReader reader = cmd.ExecuteReader())

{

if (reader.Read()) {

Console.WriteLine(“read: id – “ + Convert.ToString(reader[0]));

Console.WriteLine(“read: SomeValue – “ + Convert.ToInt32(reader[1]));

}

// End for bp

Console.WriteLine(“exit”);

}

That is it.

Adding column to existing table and populate with default value

Bali — Wed, 29 Jul 2009 03:19:59 +0000

From time to time, we run into the scenarios of adding new columns to existing table with millions of records to meet emerging business needs. And these new columns often need initialized with default value. In this post, I’d like to illustrate my solution for such problems. Let us assume,

Database: TestDB

Existing table: TestTable

Existing columns: ID, C1, C2

And need to add,

Column name: “NewColumn”

Default value=”0”

SQLType=”INT”

Most simple solution would be:

USE TestDB;

– Add ‘NewColumn’ column and poplulate this column as 0

ALTER TABLE TestTable ADD NewColumn INT;

UPDATE TestTable SET NewColumn = 0;

Often things are not that simple. We often get other questions regarding this problem. Hereby I list them as FAQs.

Q1: My existing table is very complicated with lots of foreign keys and indexes. Does this solution work for that?

A1: Maybe not. I strongly recommend you solve this by creating a new table with the correct order, and copy all the records from the existing one to the new one.

Q2: Your solution will put newly-inserted columns to the last. Can we put them to certain specific places? I am asking because our business rule needs keep audit column in the end.

A2: Unfortunately, there is no quick way to add them in a specific place in the column order in T-SQL. One thing worth mentioning is that column order does not matter because you can select the columns in any order you want.

Q3: Your solution looks fine for me, but I get hundreds of tables to do the same thing. Can I put this into a stored procedure?

A3: Yes and No. Alter table can’t take dynamic parameters. So it is impossible to create SP such as:

– INCORRECT SAMPLE. DO NOT TAKE IT.

CREATE PROCEDURE sp_addcolumn

@tablename varchar(50) = 0,

@columnname varchar(50) = 0,

@datatype varchar (50) = 0

ALTER TABLE @tablename

ADD COLUMN @columnname @datatype

END

However we can do it in another way like this:

– Correct sample

CREATE PROCEDURE sp_addcolumn

@tableName VARCHAR(50) = 0,

@colName VARCHAR(50) = 0,

@dataType VARCHAR (50) = 0

DECLARE @tsql VARCHAR (200)

SET @tsql = ‘ALTER TABLE ‘ + @tableName + ‘ ADD ‘ + @colName + ‘ ‘ + @dataType

EXEC(@tsql)

SET @tsql = ‘UPDATE ‘ + @tableName + ‘ SET ‘ + @colName + ‘= 0′

EXEC(@tsql)

– The way to use the SP is as followings:

– EXEC sp_addcolumn ‘TestTable’, ‘NewColumn’, ‘INT’