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
我希望按代码分组,并且每次检查该组中的任何记录是否包含Page’999′,如果是,则返回’True’.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法来构建这样的查询？
解决方法
select code,max(case when page = '999' then 1 else 0 end) as has999 from table group by code
