Sometimes we get the data that needs to be unique but can also get NULL records. Existing ways to achieve uniqueness doesn’t allow NULLs (Primary Key) or allow max one NULL (Unique Constraint).
Let’s take an example to understand this better. Suppose, you have an
Employee table with fields like Id, FirstName, MiddleName, LastName, Email etc. As per requirement, email needs to be unique (if supplied), however, users are also allowed to register without entering email and hence in the database
Email is a nullable field.
So how would you achieve the
Email uniqueness along with having more than one NULLs.
CREATE UNIQUE NONCLUSTERED INDEX [UX_Employee_Email] ON [dbo].
WHERE Email IS NOT NULL
Above code will ensure that
Email doesn’t have duplicate data however it may store more than one NULLs.
I hope you may have liked the tip. You share your comments.
As we know that in Web API, CORS is by default disabled due to security reasons. and hence if a client tries to access API in different server and port, you can end up with error as “
Origin http://localhost:xxxx is not allowed by Access-Control-Allow-Origin“
To enable it in ASP.NET Core Web API, there are few steps involved as following.
Go to startup.cs
Put code as follows inside ConfigureServices method
Put code as follows inside Configure method
options => options.WithOrigins("http://localhost", "https://localhost")
In the WithOrigins array, you can add or remove the client URL based on your local machine domain and port settings.
Hope you found the post useful. Please let me know your comment below.