How is the explode function used in SQL?

There is no built-in explode function in SQL, but you can achieve similar functionality by using other functions such as SUBSTRING_INDEX and GROUP_CONCAT. SUBSTRING_INDEX can retrieve a portion of a string based on a specified delimiter, while GROUP_CONCAT can concatenate multiple rows of data into one string.

For example, if we have a field containing comma-separated values and we want to split this field into multiple rows of data, we can use the following SQL statement:

SELECT SUBSTRING_INDEX(data, ',', 1) AS value
FROM table
UNION ALL
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(data, ',', 2), ',', -1) AS value
FROM table
UNION ALL
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(data, ',', 3), ',', -1) AS value
FROM table
-- 依次类推，根据需要拆分的段数来添加 UNION ALL 语句

This will allow you to split comma-separated values in one field into multiple rows of data output. The number of splits needed will depend on the actual situation.