方便函数 === ## 知识点 - length #长度 - concat # 连接两个值 - as # 别名 - substring # 切分字符串 string(字符串,开头,结尾) - random #随机数 ## 实战 ``` > select player,length(player) from users; > select playyer,concat(player,'/',team) from users; > select player,concat(player,'/',team) as "球员信息" from users; > select substring(team,1,1) as "球队首文字" from users; > select concat("我",substring(team,1,1) ) as "球队首文字" from users; > select random(); > select * from users order by random(); > select * from users order by random() limit 1; ```