改变字段类型,将表 dailykt的 ts_code字段类型改为 varchar(60)
alter table dailykt modify column ts_code varchar(60);
对表 dailykt 建立联合索引(trade_date,ts_code)
alter table dailykt add primary key(trade_date,ts_code);
读取表dailykt 里字段ts_code='300167.SZ’的 按照 trade_date 倒序最后10条数据,
select * from dailykt where ts_code='300167.SZ' order by trade_date desc limit 10 ;