SQL Server : T-SQL : WHILE Loop Syntax

  WHILE SomeConditionTrue
    BEGIN
      -- Execute code here
    END

SQL Server : T-SQL: IF Conditional Syntax

IF SomeCondition
  BEGIN
    -- Execute some code here
  END
ELSE
  BEGIN
   -- Execute some code here
  END

Else is optional

SQL Server : T-SQL Basics: Variables

T-SQL variables allows you to store and assign values in your T-SQL code.  Variables is a storage unit in programming which allows you to refer back to it at a later time.

T-SQL variables have the following characteristics:

• Local variables must be prefixed @
• Global variables must be prefixed with @@
• Must be declared with the DECLARE statement
• Must specify the data type when declared

Declaring variables

    DECLARE @employeeID INT;
    DECLARE @firstName CHAR(10), @lastName CHAR(20);

As you can see from the above example you can declare a single variable or declare multiple variables with a comma separated list.

SQL : TRANSACTION

Transaction processing is a concept in SQL that allows you to execute a query or rollback the changes if something goes wrong.  A way of enforcing the data integrity of the database.  As such, you can only rollback INSERT, UPDATE, and DELETE.  Not that there's any use in rolling back a SELECT statement because there's no change in data.

The following is how you would wrap a transaction around a DELETE statement:

BEGIN TRANSACTION
DELETE Products WHERE ProductID = 87
COMMIT TRANSACTION

The above query will only execute if there are no errors, if there's an error the transaction will be rolled back. That's it, that's the whole concept of what a transaction is, if there are no errors then you should get the following message.

(1 row(s) affected)

If you are dealing with multiple statements then you can use the SAVE TRANSACTION, SAVE TRANSACTION allows you to create a placeholder so that you can rollback a transaction at a checkpoint.

ASP.NET: Get a Single Value From a Stored Procedure Part 7

Sometimes you need to call a stored procedure that only returns one value. It would be overkill to use the SqlDataReader to store just one value. You can use the SqlCommand.ExecuteScalar() method instead to retrieve just one value from the database.
Here is how you would call the "GetProductsAvgPrice" stored procedure in the Northwind database.

1.  First you need create a stored procedure in the SQL Server that will return just one value the average price of products in Products table in the Northwind database. Run this code in the SQL Server query editor window

USE Northwind;
GO
CREATE PROCEDURE GetProductsAvgPrice
AS
    SELECT AVG(UnitPrice)
    FROM Products;
GO

2.  In your C# code file you need the namespaces

using System.Web.Configuration;
using System.Data.SqlClient;
using System.Data;

SQL Server: Granting Access Permissions to Stored Procedures For IIS Part 8

In SQL Server type in the following command in the Query Window:

USE Northwind;
Grant EXEC ON OBJECT::dbo.GetProducts TO "NT AUTHORITY\NETWORK SERVICE";
GO

The command above grants execution permission for user "NT AUTHORITY\NETWORK SERVICE" on the stored procedure dbo.GetProducts

dbo = owner schema
GetProducts = name of stored procedure
"NT AUTHORITY\NETWORK SERVICE" = user that IIS uses to access SQL Server

ASP.NET SQL Server: Granting Access Permissions to Stored Procedures For IIS Part 8

In SQL Server type in the following command in the Query Window:

USE Northwind;
Grant EXEC ON OBJECT::dbo.GetProducts TO "NT AUTHORITY\NETWORK SERVICE";
GO

The command above grants execution permission for user "NT AUTHORITY\NETWORK SERVICE" on the stored procedure dbo.GetProducts

dbo = owner schema
GetProducts = name of stored procedure
"NT AUTHORITY\NETWORK SERVICE" = user that IIS uses to access SQL Server

ASP.NET: Calling Stored Procedure With A Parameter With SqlParameter Part 6

Today we will be calling a stored procedure in SQL Server that we've created earlier in this blog call selProductsBySupplierID.  The stored procedure takes one input parameter call @SupplierID which takes an int.

ASP.NET T-SQL: Stored Procedures (SELECT), SELECT Products and The Supplier Part 5

In most of your projects you will have to work with stored procedures.  As a developer most of the time you only have to concern yourself with the basic stored procedures such as the SELECT, INSERT, UPDATE, and DELETE stored procedures.  If there's a DBA then you will probably be handed a stored procedure written by the database god.  But if you are the only developer in the five mile radius you might have to get your hands dirty and roll your own stored procedure.  In this tutorial we will be creating a select stored procedure.

ASP.NET T-SQL: Stored Procedures (UPDATE), UPDATE An Existing Product In Northwind Part 4

Here is how you would create a stored procedure to update an a new record into the Products table in the Northwind database.

USE Northwind
GO
CREATE PROCEDURE dbo.updProduct(
 @ProductID int,
 @ProductName nvarchar(40),
 @SupplierID int = null,  --default is null
 @CategoryID int = null,
 @QuantityPerUnit nvarchar(20) = null,
 @UnitPrice money = null,
 @UnitsInStock smallint = null,
 @UnitsOnOrder smallint = null,
 @ReorderLevel smallint = null,
 @Discontinued bit)
AS
UPDATE Products 
 SET ProductName = @ProductName,
  SupplierID = @SupplierID,
  CategoryID = @CategoryID,
  QuantityPerUnit = @QuantityPerUnit,
  UnitPrice = @UnitPrice,
  UnitsInStock = @UnitsInStock,
  UnitsOnOrder = @UnitsOnOrder,
  ReorderLevel = @ReorderLevel,
  Discontinued = @Discontinued
WHERE Products.ProductID = @ProductID
GO

ASP.NET T-SQL: Stored Procedures (DELETE), DELETE An Existing Northwind Product Part 3

To create the delete procedure type in the following code in the SQL editor window in "Microsoft SQL Server Management Studio"

USE Northwind
GO
CREATE PROCEDURE dbo.delProduct @ProductID int
AS
DELETE FROM Products
WHERE Products.ProductID = @ProductID
GO

The stored procedure only takes in one input parameter which is the ProductID, the DELETE statement needs a ProductID because if there is no WHERE clause, every record in the product in the Products table will be deleted. Make sure you backup the table before you work with a DELETE stored procedure.
Here is how would execute the stored procedure

EXEC dbo.delProduct 78

Blogs In the T-SQL Series:

• T-SQL: Stored Procedure (INSERT), INSERT A New Product In Northwind Part 1
• ASP.NET : Stored Procedures (INSERT), Insert a new Northwind Product Part 2
• T-SQL: Stored Procedures (DELETE), DELETE An Existing Northwind Product Part 3
• T-SQL: Stored Procedures (UPDATE), UPDATE An Existing Product In Northwind Part 4
• T-SQL: Stored Procedures (SELECT), SELECT Products and The Supplier Part 5
• ASP.NET: Calling Stored Procedure With A Parameter With SqlParameter Part 6
• ASP.NET: Get a Single Value From a Stored Procedure Part 7
• SQL Server: Granting Access Permissions to Stored Procedures For IIS Part 8

ASP.NET T-SQL: Stored Procedure (INSERT), INSERT A New Product In Northwind Part 1

Here is how you would create a stored procedure to insert a new record into the Products table in the Northwind database.

USE Northwind
GO
CREATE PROCEDURE dbo.addProduct(
 @ProductName nvarchar(40),
 @SupplierID int = null,  --default is null
 @CategoryID int = null,
 @QuantityPerUnit nvarchar(20) = null,
 @UnitPrice money = null,
 @UnitsInStock smallint = null,
 @UnitsOnOrder smallint = null,
 @ReorderLevel smallint = null,
 @Discontinued bit)
AS
INSERT INTO Products(ProductName,
 SupplierID,
 CategoryID,
 QuantityPerUnit,
 UnitPrice,
 UnitsInStock,
 UnitsOnOrder,
 ReorderLevel,
 Discontinued)
VALUES(@ProductName,
 @SupplierID,
 @CategoryID,
 @QuantityPerUnit,
 @UnitPrice,
 @UnitsInStock,
 @UnitsOnOrder,
 @ReorderLevel,
 @Discontinued)
GO

When you see a parameter with the = null, it means the field can have a null value. Since the ProductID is auto incremented you don't include it. The data types must match the fields in the database.
Here is how you would execute the stored procedure

EXEC dbo.addProduct @ProductName ='Teh',
 @SupplierID = DEFAULT,
 @CategoryID = DEFAULT,
 @QuantityPerUnit ='20 boxes x 12 oz.',
 @UnitPrice = 12.99,
 @UnitsInStock = 5,
 @UnitsOnOrder = 6,
 @ReorderLevel = DEFAULT,
 @Discontinued = 0

When you see a parameter with = DEFAULT it means to assign the DEFAULT value to the field, if the execution is completed successfully you should see the message.

(1 row(s) affected)




Blogs In the T-SQL Series:

• T-SQL: Stored Procedure (INSERT), INSERT A New Product In Northwind Part 1
• ASP.NET : Stored Procedures (INSERT), Insert a new Northwind Product Part 2
• T-SQL: Stored Procedures (DELETE), DELETE An Existing Northwind Product Part 3
• T-SQL: Stored Procedures (UPDATE), UPDATE An Existing Product In Northwind Part 4
• T-SQL: Stored Procedures (SELECT), SELECT Products and The Supplier Part 5
• ASP.NET: Calling Stored Procedure With A Parameter With SqlParameter Part 6
• ASP.NET: Get a Single Value From a Stored Procedure Part 7
• SQL Server: Granting Access Permissions to Stored Procedures For IIS Part 8