Monthly Archives: September 2015

Add constraint without checking existing data

In this post “Add constraint without checking existing data” we are going to learn how we can add a constraint on a column which already has invalid data. We create constraints to automatically enforce the integrity of the database. Using constraints we can define the rules for valid set of values for a given column. Let’s learn how we can instruct SQL Server to ignore check on the existing data during constraint creation on a column.

We have an employee table with columns EmpId, EmpName and ContactNumber. Column ContactNumber holds few invalid values, as we don’t had a constraint on this column. Now, we want to accept only valid values in the contact number column being validated with the custom business logic, but we don’t want to remove or modify the already existing data in the column. We need to put a constraint for coming data and not for existing … More

Change chart type dynamically SSRS

Today, we are going to learn how we can change chart type dynamically depending on the selected value in the report parameter in SSRS (SQL Server Reporting Services) report. Report parameter has few predefined chart type as values in the report, and depending on the selected value in the parameter, chart renders in the report.

We know that there is no any inbuilt way which can be used to change the chart type at run time in SSRS and to achieve this we need to forge a couple of things. In this post we will discuss a method which can be used to achieve this. For demo, I am using AdventureWorks2014 database in this tutorial. I have attached the zipped project file which can be downloaded from here or from the link provided at the bottom end of this post.

Let’s create a dummy project in SSDT to demonstrate how … More

Index on computed column 2

Today, we are going to learn how we can create index on a computed column which improves the performance of SELECT queries. To create a computed column, we will use an user defined function instead of inline code. Also to know about computed columns, refer my previous blog post “What is Computed Column in sql server“.

Create index on computed column

Let’s create a function, “dbo.fn_GetTotalCourseFee“, which accepts @CourseFee and @TaxPercentage as input parameters and returns the computed @TotalFee amount. To highlight some important prerequisites related to index creation on computed column, I have used a function, otherwise we can also use the inline code in column definition.

Below is the function being used to create a computed column:

CREATE FUNCTION dbo.fn_GetTotalCourseFee
 @CourseFee NUMERIC(9, 2),
 @TaxPercentage NUMERIC(9, 2)
 DECLARE @TotalFee NUMERIC(9, 2) = 0.0
 SET @TotalFee =