CONCAT()函数来拼接字符串，并使用其他函数如UPPER(), LOWER()等进行转换。，``sql，SELECT CONCAT(UPPER(column1), '_', LOWER(column2)) AS combined_column FROM table_name;，``CONCAT()函数来拼接字符串，并使用其他函数如UPPER(), LOWER()等进行转换。，``sql，SELECT CONCAT(UPPER(column1), '_', LOWER(column2)) AS combined_column FROM table_name;，``Powered By Z-BlogPHP 1.7.3