De-duplicate value from string with delimiter using ampscript

Question

I have an issue with a string variable which unfortunately contains several values(Phone numbers) with ; as the delimiter.

When the string contains several unique numbers it will list them accordingly which is fine, but when the string contains a phone number twice, it will list the number twice too.

I want to remove duplicate phone numbers.
Example: PHONE_NUMBER_LIST = 12345678; 12345678. In this case i want the output to be 12345678

PHONE_NUMBER_LIST = 12345678; 12345678

%%[
SET @rows = BuildRowsetFromString(@PHONE_NUMBER_LIST,";")

for @i = 1 to rowCount(@rows) do

SET @row = row(@rows, @i)
SET @phone_list = field(@row,1)

 ]%%

  <br>%%=v(@phone_list)=%%

    %%[

next @i ]%%

%%[ else ]%%

%%[ endif ]%%

The actual output is:

12345678
12345678

What I want is:
12345678

Answer 1

One thing you could try is storing the current phone number at each loop iteration's end to a separate variable/collection, then checking if the phone number already exists in the collection at the next iteration's start.

%%[
set @phone_number_list = "1111111;1111111;1111111;2222222;1111111;3333333"

/* initialize empty collection */
set @phone_number_collection = "" 

set @rows = BuildRowsetFromString(@phone_number_list, ";")

for @i = 1 to RowCount(@rows) do
  set @row = Row(@rows, @i)
  set @phone_number = Field(@row, 1)

  /* wrapped in arbitrary delimiters to ensure unique string */
  set @phone_number_item = Concat("~", @phone_number, "~")

  /* only output if phone number doesn't exist in collection */
  if IndexOf(@phone_number_collection, @phone_number_item) < 1 then
]%%

%%=V(@phone_number)=%%<br>

%%[
  endif

  /* add phone number to collection */
  set @phone_number_collection = Concat(
    @phone_number_collection,
    @phone_number_item
  )

next @i
]%%

Output

1111111
2222222
3333333