如何在 Oracle 查询中使用 listagg 中的条件

Question

我有 3 个表：table_A、table_B 和 table_C。 Table_A 有一个主键，由 table_B 的外键引用。 Table_C 有一个由 table_B 的外键引用的主键。设计是这样的：

T̲a̲b̲l̲e̲_̲A̲
ID_A
TextData

T̲a̲b̲l̲e̲_̲B̲:
ID_B
ID_A
ID_C

T̲a̲b̲l̲e̲ ̲C̲:
ID_C
TextData

查询：

select a.id_a,
       a.textdata,
       listagg(c.textdata, ', ') within group (order by c.id_c) data_c
from   table_a a
       inner join table_b b on (a.id_a = b.id_a)
       inner join table_c c on (b.id_c = c.id_c)
where c.textdata like :data
group by a.id_a, a.textdata;

我只是从一个 c.textdata 表中获取数据，而不是从 listagg 中获取数据。如果我尝试使用此查询：

select a.id_a,
       a.textdata,
       listagg(c.textdata, ', ') within group (order by c.id_c) data_c
from   table_a a
       inner join table_b b on (a.id_a = b.id_a)
       inner join table_c c on (b.id_c = c.id_c)
where listagg(c.textdata, ', ') like :data
group by a.id_a, a.textdata;

我收到如下错误：此处不允许使用群组功能

如何给listagg参数一个条件，因为我需要listagg中的数据？

Answer 1

您可以尝试包装您的查询：

select *
from (
      select a.id_a,
             a.textdata,
             listagg(c.textdata, ', ') within group (order by c.id_c) data_c
      from   table_a a
             inner join table_b b on (a.id_a = b.id_a)
             inner join table_c c on (b.id_c = c.id_c)
      group by a.id_a, a.textdata
     )
where data_c like :data

或使用 HAVING 对 LISTAGG 构建的字段应用条件：

select a.id_a,
       a.textdata,
       listagg(c.textdata, ', ') within group (order by c.id_c) data_c
from   table_a a
       inner join table_b b on (a.id_a = b.id_a)
       inner join table_c c on (b.id_c = c.id_c)
group by a.id_a, a.textdata
having listagg(c.textdata, ', ') within group (order by c.id_c) like :data