SQL query to find differences (changes) between tables (from one table) where field names are different

Question

Hi All,
I am looking to create a view which returns new or modified data (differences) based on a comparison between two tables.
The EMP_SOURCE table stores all employee data including duplicate staff numbers (STAFFNO):
CREATE TABLE [dbo].[EMP_SOURCE](
[FULLNAME] [varchar](255) NULL,
[JOBTITLE] [varchar](255) NULL,
[LOCATION] [varchar](255) NULL,
[COUNTRY] [varchar](255) NULL,
[STAFFNO] [varchar](255) NULL
) ON [PRIMARY]
GO
The EMP table stores unique staff numbers. This is the table used by the application.
CREATE TABLE [dbo].[EMP](
[EMP_ID] [int] NOT NULL,
[EMP_NAME] [varchar](255) NULL,
[EMP_TITLE] [varchar](255) NULL,
[EMP_OFFICE] [varchar](255) NULL,
[EMP_COUNTRY] [varchar](255) NULL,
[EMP_NUMBER] [varchar](255) NULL,
CONSTRAINT [PK_EMP] PRIMARY KEY CLUSTERED
[EMP_ID] 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
We are looking to migrate data from EMP_SOURCE to EMP but only records which are new in EMP_SOURCE and do not exist in EMP or records which are different in EMP_SOURCE from EMP.
EMP_SOURCE:
FULLNAME
JOBTITLE
LOCATION
COUNTRY
STAFFNO
John Smith
Manager
London
UK
1087
Beth King
Analyst
New York
USA
2095
Karl Bent
Manager
Chicago
USA
1106
Beth King
Junior
Washington
USA
2095
Harry Kline
Consultant
Manchester
UK
2341
EMP:
EMP_ID
EMP_NAME
EMP_TITLE
EMP_OFFICE
EMP_COUNTRY
EMP_NUMBER
1
John Smith
Manager
London
UK
1087
2
Beth King
Analyst
New York
USA
2095
3
Karl Bent
Manager
Washington
USA
1106
Based on the above comparison, EMP_SOURCE table has the following differences:
FULLNAME
JOBTITLE
LOCATION
COUNTRY
STAFFNO
Harry Kline
Consultant
Manchester
UK
2341
Karl Bent
Manager
Chicago
USA
1106
Differences in red. Beth King should be completely ignored because of duplicate staff numbers (EMP_NUMBER).
Any help to create a view which returns only the differences from EMP_SOURCE would be appreciated.
INSERT INTO EMP (EMP_ID, EMP_NAME, EMP_TITLE, EMP_OFFICE, EMP_COUNTRY, EMP_NUMBER)
VALUES (1, 'John Smith', 'Manager', 'London', 'UK', '1087');
INSERT INTO EMP (EMP_ID, EMP_NAME, EMP_TITLE, EMP_OFFICE, EMP_COUNTRY, EMP_NUMBER)
VALUES (2, 'Beth King', 'Analyst', 'New York', 'USA', '2095');
INSERT INTO EMP (EMP_ID, EMP_NAME, EMP_TITLE, EMP_OFFICE, EMP_COUNTRY, EMP_NUMBER)
VALUES (3, 'Karl Bent', 'Manager', 'Washington', 'USA', '1106');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('John Smith', 'Manager', 'London', 'UK', '1087');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('Beth King', 'Analyst', 'New York', 'USA', '2095');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('Karl Bent', 'Manager', 'Chicago', 'USA', '1106');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('Beth King', 'Junior', 'Washington', 'USA', '2095');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO) VALUES ('Harry Kline', 'Consultant', 'Manchester', 'UK', '2341');

Answer 1

HI Manc !
You may use the below code to get your desired output;
CREATE TABLE [dbo].[EMP_SOURCE](
[FULLNAME] [varchar](255) NULL,
[JOBTITLE] [varchar](255) NULL,
[LOCATION] [varchar](255) NULL,
[COUNTRY] [varchar](255) NULL,
[STAFFNO] [varchar](255) NULL
GO
CREATE TABLE [dbo].[EMP](
[EMP_ID] [int] NOT NULL,
[EMP_NAME] [varchar](255) NULL,
[EMP_TITLE] [varchar](255) NULL,
[EMP_OFFICE] [varchar](255) NULL,
[EMP_COUNTRY] [varchar](255) NULL,
[EMP_NUMBER] [varchar](255) NULL
INSERT INTO EMP (EMP_ID, EMP_NAME, EMP_TITLE, EMP_OFFICE, EMP_COUNTRY, EMP_NUMBER)
VALUES (1, 'John Smith', 'Manager', 'London', 'UK', '1087');
INSERT INTO EMP (EMP_ID, EMP_NAME, EMP_TITLE, EMP_OFFICE, EMP_COUNTRY, EMP_NUMBER)
VALUES (2, 'Beth King', 'Analyst', 'New York', 'USA', '2095');
INSERT INTO EMP (EMP_ID, EMP_NAME, EMP_TITLE, EMP_OFFICE, EMP_COUNTRY, EMP_NUMBER)
VALUES (3, 'Karl Bent', 'Manager', 'Washington', 'USA', '1106');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('John Smith', 'Manager', 'London', 'UK', '1087');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('Beth King', 'Analyst', 'New York', 'USA', '2095');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('Karl Bent', 'Manager', 'Chicago', 'USA', '1106');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO)
VALUES ('Beth King', 'Junior', 'Washington', 'USA', '2095');
INSERT INTO EMP_SOURCE (FULLNAME, JOBTITLE, LOCATION, COUNTRY, STAFFNO) VALUES ('Harry Kline', 'Consultant', 'Manchester', 'UK', '2341');
SELECT FULLNAME,JOBTITLE,LOCATION,COUNTRY,STAFFNO FROM EMP_SOURCE
EXCEPT
SELECT EMP_NAME,EMP_TITLE,EMP_OFFICE,EMP_COUNTRY,EMP_NUMBER FROM Emp
Please let me know if this doesn’t work for you. Hope I have answered you correctly.
Thanks,
Hasham