Matching in 2 Waves. Second "Wave" is based on First "Wave" - sql-server

Question

I have a "matching" scenario where I need to match records from a table.
I've altered my situation to use the Northwind database .. for illustration purposes.
Given a "set" of data (put in my #holder table below), I need to find matches based on the following criteria.
If both lastname and firstname match, match on TWO or more of the following : (city-state-together OR zip) , phone, extension
If one of either lastname OR firstname match, match on THREE or more of the following : (city-state-together OR zip) , phone,
extension
Note that "city-state-together OR zip" means that I need to match on the combination of city-and-state ........ or zip..........and if all three match, (city-state-and-zip), that should still only count as "1" for the "(ColumnCityStateZipEnum + ColumnHomePhoneEnum + ColumnExtensionEnum)" calculation.
I've come up with the below. But I have 7 left joins.
Is there another way to do this kind of problem in SQL?
Use Northwind /* Or NorthwindPartial */
GO
declare #holder table ( holderidentitykey int identity (1,1), lastname varchar(32) , firstname varchar(48) , city varchar(32) , stateabbr varchar(32) , zip varchar(5) , homephone varchar(16) , extension varchar(8) )
insert into #holder ( lastname , firstname , city , stateabbr, zip, homephone , extension )
select null , null, null, null, null , null, null
union all select 'Davolio' , 'Nancy', null, null, '98122' , '[phone]', null /* should 'match'. lastname, firstname and TWO of the other data-elements */
union all select 'Davolio' , null, null, null, null , null, null
union all select 'Fuller' , 'Andrew', 'Tacoma', 'WA', null , null, null
union all select 'Peacock' , 'MaggyNotAMatchNoPhone', 'Redmond', 'WA', '98052' , null, null
union all select 'Peacock' , 'MaggyNotAMatchWithPhoneAndExtension', 'Redmond', 'WA', '98052' , '[phone]', '5176' /* should 'match'. lastname and THREE of the other data-elements */
/*
If both lastname and firstname match, match on TWO or more of the following : (city-state-together OR zip) , phone, extension
If one of either lastname OR firstname match, match on THREE or more of the following : (city-state-together OR zip) , phone, extension
*/
select distinct * from
(
select
holderidentitykey,
ColumnLastNameFirstNameEnum =
case
when h.lastname = eLastName.LastName and h.firstname = eFirstName.FirstName then 2
when h.lastname = eLastName.LastName then 1
when h.firstname = eFirstName.FirstName then 1
else 0
end
,
ColumnCityStateZipEnum =
case
when h.zip = eZip.PostalCode then 1
when h.city = eCity.City and h.stateabbr = eState.Region then 1
else 0
end
,
ColumnHomePhoneEnum =
case
when h.homephone = eHomePhone.HomePhone then 1
else 0
end
,
ColumnExtensionEnum =
case
when h.extension = eExtension.Extension then 1
else 0
end
, eLastName.LastName , eFirstName.FirstName, eZip.PostalCode, eCity.City, eState.Region, eHomePhone.HomePhone, eExtension.Extension
from
#holder h
left join dbo.Employees eLastName on h.lastname = eLastName.LastName
left join dbo.Employees eFirstName on h.firstname = eFirstName.FirstName
left join dbo.Employees eZip on h.zip = eZip.PostalCode
left join dbo.Employees eCity on h.city = eCity.City
left join dbo.Employees eState on h.stateabbr = eState.Region
left join dbo.Employees eHomePhone on h.homephone = eHomePhone.HomePhone
left join dbo.Employees eExtension on h.extension = eExtension.Extension
) as derived1
where
derived1.ColumnLastNameFirstNameEnum >= 2 and (ColumnCityStateZipEnum + ColumnHomePhoneEnum + ColumnExtensionEnum) >= 2
OR
derived1.ColumnLastNameFirstNameEnum >= 1 and (ColumnCityStateZipEnum + ColumnHomePhoneEnum + ColumnExtensionEnum) >= 3
-- select * from dbo.Employees e
Here is a "partial" Northwind creation if you don't have one handy.
SET NOCOUNT ON
GO
USE master
GO
if exists (select * from sysdatabases where name='NorthwindPartial')
drop database NorthwindPartial
go
DECLARE #device_directory NVARCHAR(520)
SELECT #device_directory = SUBSTRING(filename, 1, CHARINDEX(N'master.mdf', LOWER(filename)) - 1)
FROM master.dbo.sysaltfiles WHERE dbid = 1 AND fileid = 1
EXECUTE (N'CREATE DATABASE NorthwindPartial
ON PRIMARY (NAME = N''NorthwindPartial'', FILENAME = N''' + #device_directory + N'northwndPartial.mdf'')
LOG ON (NAME = N''NorthwindPartial_log'', FILENAME = N''' + #device_directory + N'northwndPartial.ldf'')')
go
GO
set quoted_identifier on
GO
/* Set DATEFORMAT so that the date strings are interpreted correctly regardless of
the default DATEFORMAT on the server.
*/
SET DATEFORMAT mdy
GO
use "NorthwindPartial"
go
if exists (select * from sysobjects where id = object_id('dbo.Employees') and sysstat & 0xf = 3)
drop table "dbo"."Employees"
GO
CREATE TABLE "Employees" (
"EmployeeID" "int" IDENTITY (1, 1) NOT NULL ,
"LastName" nvarchar (20) NOT NULL ,
"FirstName" nvarchar (10) NOT NULL ,
"Title" nvarchar (30) NULL ,
"TitleOfCourtesy" nvarchar (25) NULL ,
"BirthDate" "datetime" NULL ,
"HireDate" "datetime" NULL ,
"Address" nvarchar (60) NULL ,
"City" nvarchar (15) NULL ,
"Region" nvarchar (15) NULL ,
"PostalCode" nvarchar (10) NULL ,
"Country" nvarchar (15) NULL ,
"HomePhone" nvarchar (24) NULL ,
"Extension" nvarchar (4) NULL ,
"Photo" "image" NULL ,
"Notes" "ntext" NULL ,
"ReportsTo" "int" NULL ,
"PhotoPath" nvarchar (255) NULL ,
CONSTRAINT "PK_Employees" PRIMARY KEY CLUSTERED
(
"EmployeeID"
),
CONSTRAINT "FK_Employees_Employees" FOREIGN KEY
(
"ReportsTo"
) REFERENCES "dbo"."Employees" (
"EmployeeID"
),
CONSTRAINT "CK_Birthdate" CHECK (BirthDate < getdate())
)
GO
CREATE INDEX "LastName" ON "dbo"."Employees"("LastName")
GO
CREATE INDEX "PostalCode" ON "dbo"."Employees"("PostalCode")
GO
set quoted_identifier on
go
set identity_insert "Employees" on
go
ALTER TABLE "Employees" NOCHECK CONSTRAINT ALL
go
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(1,'Davolio','Nancy','Sales Representative','Ms.','12/08/1948','05/01/1992','507 - 20th Ave. E.
Apt. 2A','Seattle','WA','98122','USA','[phone]','5467',null,'Education includes a BA in psychology from Colorado State University in 1970. She also completed "The Art of the Cold Call." Nancy is a member of Toastmasters International.',2,'http://accweb/emmployees/davolio.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(2,'Fuller','Andrew','Vice President, Sales','Dr.','02/19/1952','08/14/1992','908 W. Capital Way','Tacoma','WA','98401','USA','[phone]','3457',null,'Andrew received his BTS commercial in 1974 and a Ph.D. in international marketing from the University of Dallas in 1981. He is fluent in French and Italian and reads German. He joined the company as a sales representative, was promoted to sales manager in January 1992 and to vice president of sales in March 1993. Andrew is a member of the Sales Management Roundtable, the Seattle Chamber of Commerce, and the Pacific Rim Importers Association.',NULL,'http://accweb/emmployees/fuller.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(3,'Leverling','Janet','Sales Representative','Ms.','08/30/1963','04/01/1992','722 Moss Bay Blvd.','Kirkland','WA','98033','USA','[phone]','3355',null,'Janet has a BS degree in chemistry from Boston College (1984). She has also completed a certificate program in food retailing management. Janet was hired as a sales associate in 1991 and promoted to sales representative in February 1992.',2,'http://accweb/emmployees/leverling.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(4,'Peacock','Margaret','Sales Representative','Mrs.','09/19/1937','05/03/1993','4110 Old Redmond Rd.','Redmond','WA','98052','USA','[phone]','5176',null,'Margaret holds a BA in English literature from Concordia College (1958) and an MA from the American Institute of Culinary Arts (1966). She was assigned to the London office temporarily from July through November 1992.',2,'http://accweb/emmployees/peacock.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(5,'Buchanan','Steven','Sales Manager','Mr.','03/04/1955','10/17/1993','14 Garrett Hill','London',NULL,'SW1 8JR','UK','(71) 555-4848','3453',null,'Steven Buchanan graduated from St. Andrews University, Scotland, with a BSC degree in 1976. Upon joining the company as a sales representative in 1992, he spent 6 months in an orientation program at the Seattle office and then returned to his permanent post in London. He was promoted to sales manager in March 1993. Mr. Buchanan has completed the courses "Successful Telemarketing" and "International Sales Management." He is fluent in French.',2,'http://accweb/emmployees/buchanan.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(6,'Suyama','Michael','Sales Representative','Mr.','07/02/1963','10/17/1993','Coventry House
Miner Rd.','London',NULL,'EC2 7JR','UK','(71) 555-7773','428',null,'Michael is a graduate of Sussex University (MA, economics, 1983) and the University of California at Los Angeles (MBA, marketing, 1986). He has also taken the courses "Multi-Cultural Selling" and "Time Management for the Sales Professional." He is fluent in Japanese and can read and write French, Portuguese, and Spanish.',5,'http://accweb/emmployees/davolio.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(7,'King','Robert','Sales Representative','Mr.','05/29/1960','01/02/1994','Edgeham Hollow
Winchester Way','London',NULL,'RG1 9SP','UK','(71) 555-5598','465',null,'Robert King served in the Peace Corps and traveled extensively before completing his degree in English at the University of Michigan in 1992, the year he joined the company. After completing a course entitled "Selling in Europe," he was transferred to the London office in March 1993.',5,'http://accweb/emmployees/davolio.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(8,'Callahan','Laura','Inside Sales Coordinator','Ms.','01/09/1958','03/05/1994','4726 - 11th Ave. N.E.','Seattle','WA','98105','USA','[phone]','2344',null,'Laura received a BA in psychology from the University of Washington. She has also completed a course in business French. She reads and writes French.',2,'http://accweb/emmployees/davolio.bmp')
GO
INSERT "Employees"("EmployeeID","LastName","FirstName","Title","TitleOfCourtesy","BirthDate","HireDate","Address","City","Region","PostalCode","Country","HomePhone","Extension","Photo","Notes","ReportsTo","PhotoPath") VALUES(9,'Dodsworth','Anne','Sales Representative','Ms.','01/27/1966','11/15/1994','7 Houndstooth Rd.','London',NULL,'WG2 7LT','UK','(71) 555-4444','452',null,'Anne has a BA degree in English from St. Lawrence College. She is fluent in French and German.',5,'http://accweb/emmployees/davolio.bmp')
go
set identity_insert "Employees" off
go
ALTER TABLE "Employees" CHECK CONSTRAINT ALL
go
set quoted_identifier on
go
Select * from "Employees"

Answer 1

It's probably helpful to analyse your match rule a little, if we break it down we can see that the non-negotiable condition for a match is that either the FirstName OR the LastName matches. So let's build a query where we join only those rows from the employee table:
...
FROM #holder As h
JOIN Employee As e
ON h.FirstName = e.FirstName
OR h.LastName = e.LastName
...
Now that we're only looking at rows which meet the minimum criteria, we can assess the others. Basically your rule says that if either FirstName or LastName match, then we need a minimum of three of the following (let's assume that we matched FirstName):
Match LastName
Match City AND State, OR PostalCode
Match HomePhone
Match Extension
You present different rules depending if both FirstName and LastName match, but as long as you have one of those two then it so happens that the rules are mathematically equivalent from the perspective that I'm taking.
So we can take our potential match rows and just count how many of those matching attributes there are, and filter out rows where there aren't enough.
Select h.holderidentitykey, e.*
From #holder As h
Join Employees As e
On h.FirstName = e.FirstName
Or h.lastname = e.LastName
Where iif(h.firstname = e.firstname, 1, 0) +
iif(h.lastname = e.LastName, 1, 0) +
iif((h.city = e.City AND h.stateabbr = e.Region) OR h.zip = e.PostalCode, 1, 0) +
iif(h.homephone = e.HomePhone, 1, 0) +
iif(h.extension = e.Extension, 1, 0) >= 4;
Please note that this approach may not scale well if you have large tables (1M+) and want to match often, but if/when those situations occur then you could look at refactoring.