1. 什么是存储过程？

存储过程是一些预编译的SQL语句

查询SQL执行顺序

• FROM/JOIN and all the ON conditions
• WHERE
• GROUP BY
• HAVING
• SELECT (including window functions)
• ORDER BY
• LIMIT

  示例SQL

  根据国家面积列出各个州最大的国家

  SELECT continent, name, area FROM world x
  WHERE area >= ALL
    (SELECT area FROM world y
        WHERE y.continent=x.continent
          AND area>0)