# Quiz

+ 1)建表语句如下，请问下列哪几个查询会使用到索引 `idx_abc` ?（请选择 2 项）
```
CREATE TABLE t (
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
a INT NOT NULL,
b INT NOT NULL,
c INT NOT NULL,
d INT NOT NULL,
key idx_abc (a, b, c)
);
```
  + A.`select * from t where c = 4 and a = 100 and b < 99;` 
  + B.`select * from t where c = 100 and b = 99;` 
  + C.`select a, b, c, d from t;`
  + D.`select a, b from t;`
-------------------------------------------------------------
A，D