Question

select 
    distinct on (productid)p.product,
    pb.productid, 
    pb.mrp,
    pb.ptr,
    pb.ssr,
    pt.patent
from  prod_batch pb
    inner Join  prod_patent pt using(patentid) 
    inner Join  prods p using(productid)  
where(qty - iqty) > 0

这会选择正确返回并获得我想要的内容。！在上面的中添加ORDER BY选择以根据product＆进行排序＃39; s名字我曾经这样写过..

select 
    distinct on (productid)p.product,
    pb.productid, 
    pb.mrp,
    pb.ptr,
    pb.ssr,
    pt.patent
from  prod_batch pb
    inner Join  prod_patent pt using(patentid) 
    inner Join  prods p using(productid)  
where(qty - iqty) > 0 
order by 
    product -- this is my column name to order by

执行此操作时出错

错误：SELECT DISTINCT ON表达式必须与初始ORDER BY匹配表达式

Answer 1

您可以尝试这样

选择 - 1

select * from (
select 
    distinct on (productid)p.product,
    pb.productid, 
    pb.mrp,
    pb.ptr,
    pb.ssr,
    pt.patent
from  prod_batch pb
    inner Join  prod_patent pt using(patentid) 
    inner Join  prods p using(productid)  
where(qty - iqty) > 0 
order by 
    product
) t order by product

选择 - 2

With cte as (
select 
        distinct on (productid)p.product,
        pb.productid, 
        pb.mrp,
        pb.ptr,
        pb.ssr,
        pt.patent
    from  prod_batch pb
        inner Join  prod_patent pt using(patentid) 
        inner Join  prods p using(productid)  
    where(qty - iqty) > 0 

) select * from cte order by product

选择 - 3

只需将您的选择放入视图

create or replace view pro_details as 
select 
    distinct on (productid)p.product,
    pb.productid, 
    pb.mrp,
    pb.ptr,
    pb.ssr,
    pt.patent
from  prod_batch pb
    inner Join  prod_patent pt using(patentid) 
    inner Join  prods p using(productid)  
where(qty - iqty) > 0

用法：select * from pro_details order by product

Answer 2

DISTINCT ON（expression [，...]）仅保留给定表达式求值的每组行的第一行。 [...]注意＆＃34;第一行＆＃34;除非使用ORDER BY确保首先出现所需的行，否则每个集合都是不可预测的。 [...] DISTINCT ON表达式必须与最左边的ORDER BY表达式匹配。

尝试以下

select 
     distinct on (productid)p.product,
     pb.productid, 
     pb.mrp,
     pb.ptr,
     pb.ssr,
     pt.patent
from  prod_batch pb
inner Join  prod_patent pt using(patentid) 
inner Join  prods p using(productid)  
where(qty - iqty) > 0 
order by 
     p.productid,p.product

Answer 3

add table aliase with field "product"

select 
    distinct on (productid)p.product,
    pb.productid, 
    pb.mrp,
    pb.ptr,
    pb.ssr,
    pt.patent
from  prod_batch pb
    inner Join  prod_patent pt using(patentid) 
    inner Join  prods p using(productid)  
where(qty - iqty) > 0 
order by 
    p.product

在“选择查询”中添加ORDER BY时出错

3 个答案: