如何在sql中提取给定列表中每个单词之前的4个单词

SELECT 
    SUBSTRING_INDEX(SUBSTRING_INDEX(column_name, ' ', -5), ' ', 1) AS word1,
    SUBSTRING_INDEX(SUBSTRING_INDEX(column_name, ' ', -4), ' ', 1) AS word2,
    SUBSTRING_INDEX(SUBSTRING_INDEX(column_name, ' ', -3), ' ', 1) AS word3,
    SUBSTRING_INDEX(SUBSTRING_INDEX(column_name, ' ', -2), ' ', 1) AS word4,
    SUBSTRING_INDEX(column_name, ' ', -1) AS word5
FROM 
    table_name
WHERE 
    column_name REGEXP '[[:<:]](word1|word2|word3|word4|word5)[[:>:]]';