聚合字段

• 用于聚合查询和排序

1. 接口

• IAggregateField

2. AggregateFieldInfo

• 参看AggregateFieldInfo

class AggregateFieldInfo(ICompareField target, string aggregate) : IAggregateField;

2.1 按列聚合扩展方法

IAggregateField Aggregate(this ICompareField field, string aggregate);
IAggregateField Sum(this ICompareField field);
IAggregateField Max(this ICompareField field);
IAggregateField Min(this ICompareField field);
IAggregateField Avg(this ICompareField field);

2.2 分组聚合扩展方法

IAggregateField Aggregate(this IGroupByView view, string aggregate, string field);
IAggregateField Sum(this IGroupByView view, string field);
IAggregateField Max(this IGroupByView view, string field);
IAggregateField Min(this IGroupByView view, string field);
IAggregateField Avg(this IGroupByView view, string field);

3. DistinctCountFieldInfo

• 参看DistinctCountFieldInfo
• 对列排重计数
• sql示意为: COUNT(DISTINCT field)

class DistinctCountFieldInfo(ICompareField field) : IAggregateField;

3.1 DistinctCount扩展方法

DistinctCountFieldInfo DistinctCount(this ICompareField field);
DistinctCountFieldInfo DistinctCount(this IGroupByView view, string field);

4. CountFieldInfo

• 参看CountFieldInfo
• 分组计数
• sql示意为: COUNT(*)

class CountFieldInfo : IAggregateField;

4.1 Count扩展方法

CountFieldInfo Count(this IGroupByView view);

4.2 分组计数排序扩展方法

• 分组计数排序调用了CountFieldInfo

TGroupByCursor CountAsc<TGroupByCursor>(this TGroupByCursor cursor)
    where TGroupByCursor : GroupByCursorBase;
TGroupByCursor CountDesc<TGroupByCursor>(this TGroupByCursor cursor)
     where TGroupByCursor : GroupByCursorBase;

5. 其他相关功能

• 本组件并非只有以上功能,其他功能参看以下文档:
• 字段简介