1.支持降序索引

CREATE TABLE ts1(a INT,b INT,INDEX idx_a_b(a ASC,b DESC));

2.隐藏索引

2.1创建表时，隐藏索引

CREATE TABLE book7(
book_id INT ,
book_name VARCHAR(100),
AUTHORS VARCHAR(100),
info VARCHAR(100) ,
COMMENT VARCHAR(100),
year_publication YEAR,
#创建不可见的索引
INDEX idx_cmt(COMMENT) invisible
);

2.2创建表以后

CREATE TABLE book7(
book_id INT ,
book_name VARCHAR(100),
AUTHORS VARCHAR(100),
info VARCHAR(100) ,
COMMENT VARCHAR(100),
year_publication YEAR,
#创建不可见的索引
INDEX idx_cmt(COMMENT)
);
ALTER TABLE book7
ADD UNIQUE INDEX uk_idx_bname(book_name) invisible;
修改索引的可见性
ALTER TABLE book7 ALTER INDEX idx_year_pub invisible; #可见—->不可见