1. Explanation and learning of type in explain: https://blog.csdn.net/dennis211/article/details/78170079
2. Explanation of all fields in explain: https://www.cnblogs.com/xiaoboluo768/p/5400990.html
1. Explanation and learning of type in explain: https://blog.csdn.net/dennis211/article/details/78170079
2. Explanation of all fields in explain: https://www.cnblogs.com/xiaoboluo768/p/5400990.html