sql MySQL：从完整的“名称”字段中提取姓氏和名字（对于Elgg）

Posted 2021-05-13

SELECT 
  -- Assumed to be trimmed
  name
  
  -- Does name contain multiple words?
  ,(LOCATE(' ', name) = 0) AS hasMultipleWords

  -- Returns the end of the string back until reaches a space. 
  --   E.g. "John Doe" => "Doe"
  --   E.g. "Francis Scott Key" => "Key"
  --   E.g. "Prince" => "Prince"
  ,REVERSE(SUBSTRING_INDEX(REVERSE(name), ' ', 1)) AS lastName

  -- Everything not included in the last name.
  --   E.g. "John Doe" => "John"
  --   E.g. "Francis Scott Key" => "Francis Scott"
  --   E.g. "Prince" => ""
  ,TRIM(SUBSTRING(name, 1, CHAR_LENGTH(name) - CHAR_LENGTH(SUBSTRING_INDEX(REVERSE(name), ' ', 1)))) AS firstNames

FROM `elgg_users_entity`
LIMIT 100