mysql同一张表不同字段的值比较

比较两个字段值是否相等
SELECT * FROM table_a WHERE account = card_num;

比较两个字段值是否不等
SELECT * FROM table_a WHERE account != card_num;

比较两个字段值大小
SELECT * FROM table_a WHERE account > card_num;
SELECT * FROM table_a WHERE account >= card_num;
SELECT * FROM table_a WHERE account < card_num;
SELECT * FROM table_a WHERE account <= card_num;