Insert to microsoft sql server user database failed - sql-server

Question

Why I can't add more than one user to yii2 application? I'm using microsoft sql server and the signup code for yii2 app has not changed yet. When there is no record in user table, I can add user by using signup page from yii.
this is the DB script
USE [IBR]
GO
/****** Object: Table [dbo].[user] Script Date: 11/05/2016 16.51.02 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[user](
[id] [int] IDENTITY(1,1) NOT NULL,
[username] [nvarchar](255) NOT NULL,
[auth_key] [nvarchar](32) NOT NULL,
[password_hash] [nvarchar](255) NOT NULL,
[password_reset_token] [nvarchar](255) NULL,
[email] [nvarchar](255) NOT NULL,
[status] [smallint] NOT NULL DEFAULT ((10)),
[created_at] [int] NOT NULL,
[updated_at] [int] NOT NULL,
PRIMARY KEY CLUSTERED
(
[id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
UNIQUE NONCLUSTERED
(
[password_reset_token] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
UNIQUE NONCLUSTERED
(
[email] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
UNIQUE NONCLUSTERED
(
[username] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
this is the screenshot.error while signup for 2nd times

Answer 1

Looks like your issue is with the [password_reset_token] column.
You have a unique constraint on that column but it allows NULL values and you're not inserting data in this statement, that's why it's seeing the NULL as a duplicate key. You can either remove the unique constraint on this field or look at inserting unique data into this field.