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1. MySQL multi-table query 1.1 Foreign Key Constraints In order to eliminate the Cartesian product in multi-table queries, MySQL can use foreign key Association queries when building tables and performing key queries between multiple tables. Foreign key: Refer to the value of one column in Table 1 (sub) and another column in Table 2 (main), ...

Physical backup and recovery: Physical backup is divided into hot backup and cold backup. Compared with logical backup, physical backup has faster backup and recovery speed. The principle is based on the cp command. Cold standby: backup MySQL database shared table space,.frm, stand-alone table space (.ibd), redo log files. Advantages: ...