先安装mysql官方示例数据库employees。没安装的可以参考：《MAC安装MYSQL官方示例数据库EMPLOYEE》

• 脚本操作：

-- 创建表employees
create table employees like employees.employees;
-- 将employees库的employees表数据插入到自己的表
insert into employeesselect * from employees.employees limit 0,10;
-- 新增数据，生日为闰年1972-02-29
insert into employeesselect '10011','1972-02-29','Jiang','David','M','1990-2-20';

4. 查询用户和出生信息

• 语句：

-- 查询用户和出生信息
select concat(e.last_name, '  ', e.first_name) as Name, e.birth_date as BirthDate from employees e;

• 查询结果：

5. 实现

　　5.1 查询当前日期、当前日期和生日间隔的年数。

• 代码：

• select concat(e.last_name, '  ', e.first_name) as Name, e.birth_date  as BirthDay,(year(now())-year(e.birth_date)) diff,now() as today
  from employees e

• 结果：

　　5.2 查询当年的生日和下一年的生日。

• 代码：

  select name,birthday,today,date_add(birthday, interval diff year) curr, -- 当年生日date_add(birthday, interval diff+1 year) next    -- 下一年生日
  from (select concat(e.last_name, '  ', e.first_name) as Name, e.birth_date  as BirthDay,(year(now())-year(e.birth_date)) diff,now() as todayfrom employees e
  ) as a

• 查询结果

　　　5.3 出生日期是29日，当年或下一年生日是28日，就将生日日期加1天

• 代码：

  select name,birthday,today,date_add(curr, interval if(day(birthday)=29 && day(curr)=28, 1, 0) day) as cur, -- 闰年运行后的当年生日date_add(next, interval if(day(birthday)=29 && day(next)=28, 1, 0) day) as next -- 闰年运行后的下一年生日
  from (select name,birthday,today,date_add(birthday, interval diff year) curr,  -- 当年生日date_add(birthday, interval diff+1 year) next -- 下一年生日from (select concat(e.last_name, '  ', e.first_name) as Name, e.birth_date  as BirthDay,(year(now())-year(e.birth_date)) diff,now() as todayfrom employees e) as a
  ) as b

• 查询结果：

　　5.4 最终代码，如果当年生日已经过了就返回下一年生日。

• 代码：

  select name,birthday,if(cur>today, cur, next) as birth_day -- 如果当年生日大于当前日期，生日为今年，否则为下一年
  from(select name,birthday,today,date_add(curr, interval if(day(birthday)=29 && day(curr)=28, 1, 0) day) as cur, -- 闰年运行后的当年生日date_add(next, interval if(day(birthday)=29 && day(next)=28, 1, 0) day) as next -- 闰年运行后的下一年生日from (select name,birthday,today,date_add(birthday, interval diff year) curr,  -- 当年生日date_add(birthday, interval diff+1 year) next -- 下一年生日from (select concat(e.last_name, '  ', e.first_name) as Name, e.birth_date  as BirthDay,(year(now())-year(e.birth_date)) diff,now() as todayfrom employees e) as a) as b
  ) as c

• 查询结果：