MySQL 查询一串连续字符串

参考：https://blog.csdn.net/qiuli_liu/article/details/81707562

SELECT
	@xi := @xi + 1 AS xc 
FROM
	( SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 ) xc1,
	( SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 ) xc2,
	( SELECT @xi := 0 ) xc0