线上问题集锦(2)

mysql and 和 or为何会致使性能差异巨大？ select t1.* from t_user t1, t_student_info t2 where t1.user_unique_code = t2.uu_id and ( t1.user_name like '%谭%' or t2.student_no like '%谭%' or t2.company like '%

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