SQL Server Full Text Search to match contact name to prevent duplicates - sql-server

Question

Using SQL Server Azure or 2017 with Full Text Search, I need to return possible matches on names.
Here's the simple scenario: an administrator is entering contact information for a new employee, first name, last name, address, etc. I want to be able to search the Employee table for a possible match on the name(s) to see if this employee has already been entered in the database.
This might happen as an autosuggest type of feature, or simply display some similar results, like here in Stackoverflow, while the admin is entering the data.
I need to prevent duplicates!
If the admin enters "Bob", "Johnson", I want to be able to match on:
Bob Johnson
Rob Johnson
Robert Johnson
This will give the administrator the option of seeing if this person has already been entered into the database and choose one of those choices.
Is it possible to do this type of match on words like "Bob" and include "Robert" in the results? If so, what is necessary to accomplish this?

Answer 1

Try this.
You need to change the #per parameter value to your requirement. It indicates how many letters out of the length of the first name should match for the result to return. I just set it to 50% for testing purposes.
The dynamic SQL piece inside the loop adds all the CHARINDEX result per letter of the first name in question, to all existing first names.
Caveats:
Repeating letters will of course be misleading, like Bob will count 3 matches in Rob because there's 2 Bs in Bob.
I didn't consider 2 first names, like Bob Robert Johnson, etc so this will fail. You can improve on that however, but you get the idea.
The final SQL query gets the LetterMatch that is greater than or equal to the set value in #per.
DECLARE #name varchar(MAX) = 'Bobby Johnson' --sample name
DECLARE #first varchar(50) = SUBSTRING(#name, 0, CHARINDEX(' ', #name)) --get the first part of the name before space
DECLARE #last varchar(50) = SUBSTRING(#name, CHARINDEX(' ', #name) + 1, LEN(#name) - LEN(#first) - 1) --get the last part of the name after space
DECLARE #walker int = 1 --for looping
DECLARE #per float = LEN(#first) * 0.50 --declare percentage of how many letters out of the length of the first name should match. I just used 50% for testing
DECLARE #char char --for looping
DECLARE #sql varchar(MAX) --for dynamic SQL use
DECLARE #matcher varchar(MAX) = '' --for dynamic SQL use
WHILE #walker <> LEN(#first) + 1 BEGIN --loop through all the letters of the first name saved in #first variable
SET #char = SUBSTRING(#first, #walker, 1) --save the current letter in the iteration
SET #matcher = #matcher + IIF(#matcher = '', '', ' + ') + 'IIF(CHARINDEX(''' + #char + ''', FirstName) > 0, 1, 0)' --build the additional column to be added to the dynamic SQL
SET #walker = #walker + 1 --move the loop
END
SET #sql = 'SELECT * FROM (SELECT FirstName, LastName, ' + #matcher + ' AS LetterMatch
FROM TestName
WHERE LastName LIKE ' + '''%' + #last + '%''' + ') AS src
WHERE CAST(LetterMatch AS int) >= ROUND(' + CAST(#per AS varchar(50)) + ', 0)'
SELECT #sql
EXEC(#sql)

Answer 2

SELECT * FROM tbl_Names
WHERE Name LIKE '% user defined text %';
using a text in between % % will search those text on any position in the data.