假设MySQL数据库表:
create table T{
k int unsigned not null auto_increment,
a date,
b varchar(24),
c int,d varchar(24),
primary key(k),unique key a_index (a DESC,b DESC),
key k1(b),key k2(c),key k3(d));
如下哪些sql语句查询能较好的利用索引?( )
- A、select b from WHERE b like 'aaa%';
- B、select a,b from T WHERE a='2015-10-25' ORDER BY b ASC,c ASC;
- C、select a,b,c from T WHERE a='2015-10-25' ORDER BY b ASC;
- D、select a,b,c from T WHERE a='2015-10-25' ORDER BY a,b;
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