mysql 在逗号分隔符字段上仅选择当前年份和最大年份之间的字段

Question

I have this field on table that stores years with comma separator and I'm looking for a way to filter results containing years between range of current year and max year from field, this is what I got so far:

SELECT *, max(SUBSTRING_INDEX(years, ',', -1)) as maxyear from availability WHERE CONCAT(",", years, ",") REGEXP ",(2022|2023|2024)," GROUP BY id

years are manually inserted in REGEXP, need them to be dynamic, the maxyear in select gets the max year on each result, test code below.

FIDDLE: http://sqlfiddle.com/#!9/ffaed2/1

Answer 1

Having multiple values in a column means that your database is not even first normal form (1NF) . The reason why this is to be avoided is demonstrated by your very question.

Your question is a bit vague. You say, "I'm looking for a way to filter results containing years between range of current year and max year from field." The current year is 2022 and the "max year from field" would be 2027 based on the data you supplied, so you should return 3 rows. But this is equivalent to saying you want to filter results containing years >= the current year. In that case the following should work:

Try:

SELECT *, SUBSTRING_INDEX(years, ',', -1) as maxyear FROM availability
WHERE SUBSTRING_INDEX(years, ',', -1) >= YEAR(CURDATE())

But if the "max year" is a year to be supplied, for example 2024, then:

SELECT *, SUBSTRING_INDEX(years, ',', -1) as maxyear FROM availability
WHERE SUBSTRING_INDEX(years, ',', -1) between YEAR(CURDATE()) and 2024