How to SELECT DISTINCT records with INNER JOIN? - sql

Question

I have two tables Finance Commissions May2021 (FMAY) and Consolidated Client Codes (CCC).
Here is the code for Insert Into: For table FMAY
USE [FinanceCommissions26May2021]
GO
/****** Object: Table [dbo].[Finance_Commissions_May26_2021$] Script Date: 22/06/2021 11:06:26 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Finance_Commissions_May26_2021$](
[Lender Reference] [nvarchar](255) NULL,
[F2] [nvarchar](255) NULL,
[F3] [nvarchar](255) NULL,
[Client] [nvarchar](255) NULL,
[F5] [nvarchar](255) NULL,
[Supplier] [nvarchar](255) NULL,
[Product] [nvarchar](255) NULL,
[Settlement / Inception Date] [nvarchar](255) NULL,
[Base Value] [nvarchar](255) NULL,
[Original Loan Amount] [money] NULL,
[Adviser Split (%)*] [money] NULL,
[F12] [nvarchar](255) NULL,
[Supplier_Amount_(incl GST)] [money] NULL,
[Supplier_Amount_(GST)] [money] NULL,
[Adviser Share (ex GST)] [money] NULL,
[F16] [nvarchar](255) NULL,
[F17] [nvarchar](255) NULL,
[Adviser Share (GST)] [money] NULL,
[Adviser Share (incl GST)] [money] NULL,
[LastNameOnly] [nvarchar](255) NULL,
[FirstNameOnly] [nvarchar](255) NULL,
[FirstFourLastName] [nvarchar](255) NULL,
[ClientCode] [nvarchar](255) NULL,
[IndexMatch] [nvarchar](255) NULL,
[F25] [nvarchar](255) NULL,
[F26] [float] NULL
) ON [PRIMARY]
GO
FMAY
Table FMAY contains the following columns:
commission amounts
a Lender Reference Number
client names (LastName, FirstName).
This report comes in monthly and contains monthly commissions for some of the clients (usually contains 350-400 records).
CREATE TABLE [Finance_Commissions_May26_2021$] (
CommissionAmount,
LenderReferenceNumber,
ClientLastName,
ClientFirstName
)
& here is the code for table CCC:
USE [FinanceCommissions26May2021]
GO
/****** Object: Table [dbo].[Consolidated_ClientCodes$] Script Date: 22/06/2021 11:07:27 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Consolidated_ClientCodes$](
[FirstFourLastName] [nvarchar](255) NULL,
[ClientCode] [nvarchar](255) NULL,
[Client] [nvarchar](255) NULL
) ON [PRIMARY]
GO
CCC
Table CCC contains the following columns:
client names
(different format though - i.e. FirstName,LastName)
a client code (which is a unique identifier (Primary key) assigned to each client.
Client code takes the form of SMIT123.
e.g. for "John, Smith" it's SMIT123
for "Mark, Smith" it's SMIT345, and so on.
i.e. First Four letters of last name followed by a unique 3 digit code.
This table contains Client names and unique Client codes for ALL clients (more than 7000 records)
CREATE TABLE ['20210617145928-Exception - No C$'] (
ClientCode PRIMARY KEY, -- '\w\w\w\w\d\d\d'
FirstName,
LastName
)
The problem
My aim is : To assign this unique Client code to each client within the FMAY table.
Since there was NO common column between tables FMAY and CCC, I created a new column (FirstFourLastName) which parses out FirstFour letters of Last Name (like "SMIT") from both Tables.
Then using this new column (FirstFourLastName), I wrote code for Inner Join in SQL with an aim to assign the Unique "Client Code" to each record in table FMAY.
I am able to get the correct client code assigned but not able to ONLY select distinct records.
My code is:
select
FMAY.[Lender Reference],
CCC.Client,
CCC.ClientCode,
FMAY.FirstFourLastName,
FMAY.[Adviser Share (ex GST)],
FMAY.[Adviser Share (GST)],
FMAY.[Adviser Share (incl GST)],
FMAY.Product
from
[FinanceCommissions26May2021].[dbo].[Finance_Commissions_May26_2021$] FMAY
inner join [FinanceCommissions26May2021].[dbo].['20210617145928-Exception - No C$'] CCC on
FMAY.FirstFourLastName = CCC.FirstFourLastName
The above code is giving me 6300 records, with the correct client code attached to each record though! However, I only need to assign Client Code to the 350-400 records in the FMAY table.
How can I select distinct records for my problem please?

Answer 1

It looks like there might be multiple similar values for FirstFourLastName and with join on FirstFourLastName you're getting every combination possible. For example:
FMAY table
LenderReference
FirstFourLastName
123
smit
456
smit
CCC Table
clientcode
FirstFourLastName
smit123
smit
smit456
smit
Omitting all other columns, the inner join on FirstFourLastName would produce:
LenderReference
clientcode
FirstFourLastName
123
smit123
smit
123
smit456
smit
456
smit123
smit
456
smit456
smit
I would double check that the clientcode is definitely attaching correctly. If LenderReference is unique, you could run distinct count of clientcodes against it.