Create a composite index a_b_c with three fields a, b, and c in mysql. Which of the following queries is the least efficient?
A, select * from test where a = 10 and b> 50
B 、 select * from test where a = 10 and b> 10 order by c
C, select * from test where a = 10 and b = 10 order by a
D, select * from test where a = 10 and b = 10 order by c
Answer:B
Create a composite index a_b_c with three fields a, b, and c in mysql. Which of the following queries is the least efficient?
A, select * from test where a = 10 and b> 50 B 、 select * from test where a = 10 and b> 10 order by c C, select * from test where a = 10 and b = 10 order by a D, select * from test where a = 10 and b = 10 order by c