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Updated 表达式函数 (markdown)

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2025-09-05 18:22:29 +08:00
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表达式函数.md

@@ -125,6 +125,38 @@ fsql.Select<T1, T2>()
> v1.6.0 利用自定义解析功能，增加 SqlExt.Rank().Over().PartitionBy(...)、MySql group_concat 常用函数，欢迎 PR 补充
FreeSql 默认集成了 SqlExt.cs 扩展解析方法：
| lambda | sql | 说明 |
| --------------------------------------------------- | -------------------------------------------------- | -------------- |
| SqlExt.IsNull(id, 0) | isnull/ifnull/coalesce/nvl | 兼容各大数据库 |
| SqlExt.DistinctCount(id) | count(distinct id) | |
| SqlExt.AggregateCount() | count(1) | 聚合函数 |
| SqlExt.AggregateCount(id > 0) | sum(case when id > 0 then 1 else 0 end) | |
| SqlExt.AggregateSum(id) | sum(id) | |
| SqlExt.AggregateAvg(id) | avg(id) | |
| SqlExt.AggregateMax(id) | max(id) | |
| SqlExt.AggregateMin(id) | min(id) | |
| SqlExt.GreaterThan | &gt; | 大于 |
| SqlExt.GreaterThanOrEqual | &gt;= | 大于或等于 |
| SqlExt.LessThan | &lt; | 小于 |
| SqlExt.LessThanOrEqual | &lt;= | 小于 |
| SqlExt.EqualIsNull | IS NULL | 是否为 NULL |
| SqlExt.Case(字典) | case when .. end | 根据字典 case |
| SqlExt.GroupConcat | group_concat(distinct .. order by .. separator ..) | MySql |
| SqlExt.FindInSet | find_in_set(str, strlist) | MySql |
| SqlExt.StringAgg | string_agg(.., ..) | PostgreSQL |
| SqlExt.Rank().Over().PartitionBy().ToValue() | rank() over(partition by xx) | 开窗函数 |
| SqlExt.DenseRank().Over().PartitionBy().ToValue() | dense_rank() over(partition by xx) | |
| SqlExt.Count(id).Over().PartitionBy().ToValue() | count(id) over(partition by xx) | |
| SqlExt.Sum(id).Over().PartitionBy().ToValue() | sum(id) over(partition by xx) | |
| SqlExt.Avg(id).Over().PartitionBy().ToValue() | avg(id) over(partition by xx) | |
| SqlExt.Max(id).Over().PartitionBy().ToValue() | max(id) over(partition by xx) | |
| SqlExt.Min(id).Over().PartitionBy().ToValue() | min(id) over(partition by xx) | |
| SqlExt.RowNumber(id).Over().PartitionBy().ToValue() | row_number(id) over(partition by xx) | |
> 以上是利用《自定义解析》实现的功能
## 子表Exists
```csharp