How can I efficiently parse first, middle, and last names from a single 'fullname' field in SQL, handling various data inconsistencies and special cases?

Parse First, Middle, and Last Name from Full Name Field using SQL

When processing data, it's often necessary to separate names into their constituent parts for easier manipulation. In this case, we need to extract the first, middle, and last names from a 'fullname' field while accounting for common data variations.

Efficient Solution with 90% Accuracy

The provided example provides a practical solution that handles most cases with a high degree of accuracy:

SELECT
  FIRST_NAME.ORIGINAL_INPUT_DATA,
  FIRST_NAME.TITLE,
  FIRST_NAME.FIRST_NAME,
  CASE
    WHEN 0 = CHARINDEX(' ', FIRST_NAME.REST_OF_NAME)
    THEN NULL  -- No more spaces? Assume rest is last name
    ELSE SUBSTRING(FIRST_NAME.REST_OF_NAME, 1, CHARINDEX(' ', FIRST_NAME.REST_OF_NAME) - 1)
  END AS MIDDLE_NAME,
  SUBSTRING(FIRST_NAME.REST_OF_NAME, 1 + CHARINDEX(' ', FIRST_NAME.REST_OF_NAME), LEN(FIRST_NAME.REST_OF_NAME)) AS LAST_NAME
FROM
  (
    SELECT
      TITLE.TITLE,
      CASE
        WHEN 0 = CHARINDEX(' ', TITLE.REST_OF_NAME)
        THEN TITLE.REST_OF_NAME -- No space? Return the whole thing
        ELSE SUBSTRING(TITLE.REST_OF_NAME, 1, CHARINDEX(' ', TITLE.REST_OF_NAME) - 1)
      END AS FIRST_NAME,
      CASE
        WHEN 0 = CHARINDEX(' ', TITLE.REST_OF_NAME)
        THEN NULL  -- No spaces at all? Then 1st name is all we have
        ELSE SUBSTRING(TITLE.REST_OF_NAME, CHARINDEX(' ', TITLE.REST_OF_NAME) + 1, LEN(TITLE.REST_OF_NAME))
      END AS REST_OF_NAME,
      TITLE.ORIGINAL_INPUT_DATA
    FROM
      (
        SELECT
          -- If the first three characters are in this list,
          -- then pull it as a "title". Otherwise return NULL for title.
          CASE
            WHEN SUBSTRING(TEST_DATA.FULL_NAME, 1, 3) IN ('MR ', 'MS ', 'DR ', 'MRS')
            THEN LTRIM(RTRIM(SUBSTRING(TEST_DATA.FULL_NAME, 1, 3)))
            ELSE NULL
          END AS TITLE,
          -- If you change the list, don't forget to change it here, too.
          CASE
            WHEN SUBSTRING(TEST_DATA.FULL_NAME, 1, 3) IN ('MR ', 'MS ', 'DR ', 'MRS')
            THEN LTRIM(RTRIM(SUBSTRING(TEST_DATA.FULL_NAME, 4, LEN(TEST_DATA.FULL_NAME))))
            ELSE LTRIM(RTRIM(TEST_DATA.FULL_NAME))
          END AS REST_OF_NAME,
          TEST_DATA.ORIGINAL_INPUT_DATA
        FROM
          (
            SELECT
              -- Trim leading & trailing spaces before trying to process
              -- Disallow extra spaces *within* the name
              REPLACE(REPLACE(LTRIM(RTRIM(FULL_NAME)), '  ', ' '), '  ', ' ') AS FULL_NAME,
              FULL_NAME AS ORIGINAL_INPUT_DATA
            FROM
              (
                -- Replace this block with your actual table
                SELECT 'GEORGE W BUSH' AS FULL_NAME
                UNION SELECT 'SUSAN B ANTHONY' AS FULL_NAME
                UNION SELECT 'ALEXANDER HAMILTON' AS FULL_NAME
                UNION SELECT 'OSAMA BIN LADEN JR' AS FULL_NAME
                UNION SELECT 'MARTIN J VAN BUREN SENIOR III' AS FULL_NAME
                UNION SELECT 'TOMMY' AS FULL_NAME
                UNION SELECT 'BILLY' AS FULL_NAME
              ) RAW_DATA
          ) TEST_DATA
      ) TITLE
  ) FIRST_NAME;

This query identifies and removes prefixes such as 'MR', 'MS', 'DR', and 'MRS' as separate 'TITLE' columns, handles missing names, multiple spaces in the name, and a single-part 'fullname' (first name only).

Handling Special Cases

The solution also includes a modification that addresses specific special cases, such as an empty 'fullname' field, trailing/leading spaces, multiple consecutive spaces, and a 'fullname' containing only the first name:

-- Handle the following special cases:
-- 1 - The NAME field is NULL
-- 2 - The NAME field contains leading / trailing spaces
-- 3 - The NAME field has > 1 consecutive space within the name
-- 4 - The NAME field contains ONLY the first name
-- 5 - Include the original full name in the final output as a separate column, for readability
-- 6 - Handle a specific list of prefixes as a separate "title" column

SELECT
  FIRST_NAME.ORIGINAL_INPUT_DATA,
  FIRST_NAME.TITLE,
  FIRST_NAME.FIRST_NAME,
  CASE
    WHEN 0 = CHARINDEX(' ', FIRST_NAME.REST_OF_NAME)
    THEN NULL  -- No more spaces? Assume rest is last name
    ELSE SUBSTRING(FIRST_NAME.REST_OF_NAME, 1, CHARINDEX(' ', FIRST_NAME.REST_OF_NAME) - 1)
  END AS MIDDLE_NAME,
  SUBSTRING(FIRST_NAME.REST_OF_NAME, 1 + CHARINDEX(' ', FIRST_NAME.REST_OF_NAME), LEN(FIRST_NAME.REST_OF_NAME)) AS LAST_NAME
FROM
  (
    SELECT
      TITLE.TITLE,
      CASE
        WHEN 0 = CHARINDEX(' ', TITLE.REST_OF_NAME)
        THEN TITLE.REST_OF_NAME -- No space? Return the whole thing
        ELSE SUBSTRING(TITLE.REST_OF_NAME, 1, CHARINDEX(' ', TITLE.REST_OF_NAME) - 1)
      END AS FIRST_NAME,
      CASE
        WHEN 0 = CHARINDEX(' ', TITLE.REST_OF_NAME)
        THEN NULL  -- No spaces at all? Then 1st name is all we have
        ELSE SUBSTRING(TITLE.REST_OF_NAME, CHARINDEX(' ', TITLE.REST_OF_NAME) + 1, LEN(TITLE.REST_OF_NAME))
      END AS REST_OF_NAME,
      TITLE.ORIGINAL_INPUT_DATA
    FROM
      (
        SELECT
          -- If the first three characters are in this list,
          -- then pull it as a "title". Otherwise return NULL for title.
          CASE
            WHEN SUBSTRING(TEST_DATA.FULL_NAME, 1, 3) IN ('MR ', 'MS ', 'DR ', 'MRS')
            THEN LTRIM(RTRIM(SUBSTRING(TEST_DATA.FULL_NAME, 1, 3)))
            ELSE NULL
          END AS TITLE,
          -- If you change the list, don't forget to change it here, too.
          CASE
            WHEN SUBSTRING(TEST_DATA.FULL_NAME, 1, 3) IN ('MR ', 'MS ', 'DR ', 'MRS')
            THEN LTRIM(RTRIM(SUBSTRING(TEST_DATA.FULL_NAME, 4, LEN(TEST_DATA.FULL_NAME))))
            ELSE LTRIM(RTRIM(TEST_DATA.FULL_NAME))
          END AS REST_OF_NAME,
          TEST_DATA.ORIGINAL_INPUT_DATA
        FROM
          (
            SELECT
              -- Trim leading & trailing spaces before trying to process
              -- Disallow extra spaces *within* the name
              REPLACE(REPLACE(LTRIM(RTRIM(FULL_NAME)), '  ', ' '), '  ', ' ') AS FULL_NAME,
              FULL_NAME AS ORIGINAL_INPUT_DATA
            FROM
              (
                -- Replace this block with your actual table
                SELECT 'GEORGE W BUSH' AS FULL_NAME
                UNION SELECT 'SUSAN B ANTHONY' AS FULL_NAME
                UNION SELECT 'ALEXANDER HAMILTON' AS FULL_NAME
                UNION SELECT 'OSAMA BIN LADEN JR' AS FULL_NAME
                UNION SELECT 'MARTIN J VAN BUREN SENIOR III' AS FULL_NAME
                UNION SELECT 'TOMMY' AS FULL_NAME
                UNION SELECT 'BILLY' AS FULL_NAME
                UNION SELECT NULL AS FULL_NAME
                UNION SELECT ' ' AS FULL_NAME
                UNION SELECT '    JOHN  JACOB     SMITH' AS FULL_NAME
                UNION SELECT ' DR  SANJAY       GUPTA' AS FULL_NAME
                UNION SELECT 'DR JOHN S HOPKINS' AS FULL_NAME
                UNION SELECT ' MRS  SUSAN ADAMS' AS FULL_NAME
                UNION SELECT ' MS AUGUSTA  ADA   KING ' AS FULL_NAME      
              ) RAW_DATA
          ) TEST_DATA
      ) TITLE
  ) FIRST_NAME;

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