MySQL获取最大列数，并回退到第二列

SELECT MAX(ORDINAL_POSITION) AS max_column
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'your_database_name'
AND TABLE_NAME = 'your_table_name';

SELECT column_name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'your_database_name'
AND TABLE_NAME = 'your_table_name'
AND ORDINAL_POSITION = (SELECT MAX(ORDINAL_POSITION) - 1
                        FROM INFORMATION_SCHEMA.COLUMNS
                        WHERE TABLE_SCHEMA = 'your_database_name'
                        AND TABLE_NAME = 'your_table_name');