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create table t1 (a int primary key, b int unique); insert into t1 values (1,100),(2,99),(3,98),(4,97),(5,96); EXPLAIN SELECT * FROM t1 FORCE INDEX (b) ORDER BY b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index NULL b 5 NULL # SELECT * FROM t1 FORCE INDEX (b) ORDER BY b; a b 5 96 4 97 3 98 2 99 1 100 DROP TABLE t1; |