聚合功能检查“如果含有”

Question

我有数据：

Code Page  Task 
    2 1 Activity 
    2 2 Activity 
    2 3 Activity Symbols 
    2 4 Activity Symbols 
    2 5 Activity Symbols 
    2 12 Activity 
    2 12 Activity Symbols 
    2 999 Consider 
    2 999 Constituents 
    2 999 Material 
    2 999 Material Hazards 
    316 999 Constituents 
    356 999 Constituents 
    398 999 Constituents 
    604 70 Activity Symbols 
    604 999 Constituents 

我想组由Code并为每个检查，如果任何的该组中的记录包含的“999”一个Page，如果是这样的回报'真正'。是否有一个聚合函数可以做到这一点？或者也许有更好的方式来构建这样的查询？

Answer 1

select code, 
max(case when page = '999' then 1 else 0 end) as has999 
from table 
group by code