Question

在这种情况下，有四个表：TableA，TableB和TableC，TableD和TableE

TableA -> TableB = 1-to-many
TableB -> TableC = 1-to-many
TableB -> TableD = 1-to-1
TableC -> TableE = 1-to-1

TableA { Id (PK), Field1 (float), DateField (DateTime) }
TableB { Id (PK), TableAId (FK), TableDId (FK), Field2 (float) }
TableC { Id (PK), TableBId (FK), TableEId (FK), Field3 (float) }
TableD { Id (PK), Type (tinyint) }
TableE { Id (PK), Type (tinyint) }

TableB中的一些但不是所有记录都包含TableC中的子记录。基于一些DateRange（from-to），我需要从TableA中获取所有记录及其相关记录，并计算：

TableA.Field1摘要，
TableB.Field2的摘要，按TableD.Type分组（有5种不同的类型）。
TableC.Field3的摘要，由TableE.Type（有4种不同的类型）组成。

因此，结果应包含10个计算摘要。实现这一目标的最有效方法是什么？

编辑：以下是每个摘要的伪查询示例：

SELECT SUM(a.Field1) FROM TableA a INNER JOIN TableB b ON a.Id = b.TableAId WHERE a.DateField BETWEEN DateFrom AND DateTo

SELECT SUM(b.Field2) FROM TableA a INNER JOIN TableB b ON a.Id = TableD d ON b.TableDId=d.Id WHERE a.DateField BETWEEN DateFrom AND DateTo AND d.Type = 1

SELECT SUM(b.Field2) FROM TableA a INNER JOIN TableB b ON a.Id = TableD d ON b.TableDId=d.Id WHERE a.DateField BETWEEN DateFrom AND DateTo AND d.Type = 2 // etc to 5

SELECT SUM(c.Field3) FROM TableA a INNER JOIN TableB b ON a.Id = b.TableAId INNER JOIN TableC c ON b.Id=c.TableBId INNER JOIN TableE ON c.TableEId=e.Id WHERE a.DateField BETWEEN DateFrom AND DateTo AND e.Type = 1 // 3x this query, only type is different

Answer 1

我认为这里最好的方法是使用CTE在一个查询中编写整个内容，让SQL Server的优化器找出执行此操作的最佳方法。这样我们就不会：

重复使用多个查询
创建未编入索引的表变量
创建需要写入磁盘的临时表

以下是查询：

with a as (select * from tableA where datefield between datefrom and dateto),
b as ( select * from tableB where tableB.tableAid = a.id)
    select null, sum(a.field1) from a
union 
    select d.type, sum(b.field2) 
    from b
    join tableD d on d.id = b.tableDid
    group by d.type
union 
    select e.type, sum(c.field3)
    from tableC c
    join b on b.id = c.tableBid
    join tableE e on e.id = c.tableEid

检索多个摘要

1 个答案: