Question

我在postgres中使用交叉表功能。基本SQL是：

select distinct  
       o_location,
       co_name,
       o_date,
       o_ndate,
       o_day,
       o_hour,
       o_type
  from outputs_txt
  left join courses on o_course = co_foreign
  left join locations on o_location = l_code
 where o_date = '2011-10-10' 
 order by o_hour

我的交叉表查询是

SELECT *
  FROM crosstab(
'SELECT DISTINCT
        COALESCE(o_location, '''')
       ,o_hour AS hour
       ,c.co_name
   FROM outputs_txt AS d
   LEFT JOIN courses AS c 
     on o_course = c.co_foreign
   LEFT JOIN locations as a 
     on o_location = a.l_code
  WHERE d.o_date = ''2011-10-10'''
)
AS ct(
 o_location varchar
,hour_0  varchar
,hour_1  varchar
,hour_2  varchar
,hour_3  varchar
,hour_4  varchar
,hour_5  varchar
,hour_6  varchar
,hour_7  varchar
,hour_8  varchar
,hour_9  varchar
,hour_10 varchar
,hour_11 varchar
,hour_12 varchar
,hour_13 varchar
,hour_14 varchar
,hour_15 varchar
,hour_16 varchar
,hour_17 varchar)

问题是结果都向左移动了例如，如果某个地点的课程应显示在hour_8上，则会显示在hour_0中这适用于所有地点的所有课程。它们都是左对齐的。

我哪里错了？

Answer 1

由于没有样本数据，我只能猜测。这是让我感到震惊的事：
交叉表功能中没有 ORDER BY 。我加了一个：

SELECT *
  FROM crosstab(
'SELECT DISTINCT
        COALESCE(o_location, '''')
       ,o_hour AS hour
       ,c.co_name
   FROM outputs_txt AS d
   LEFT JOIN courses AS c    ON o_course = c.co_foreign
   LEFT JOIN locations as a  ON o_location = a.l_code
  WHERE d.o_date = ''2011-10-10''
  ORDER BY 1,2'
)
AS ct(
 o_location varchar
,hour_0  varchar
,hour_1  varchar
,hour_2  varchar
,hour_3  varchar
,hour_4  varchar
,hour_5  varchar
,hour_6  varchar
,hour_7  varchar
,hour_8  varchar
,hour_9  varchar
,hour_10 varchar
,hour_11 varchar
,hour_12 varchar
,hour_13 varchar
,hour_14 varchar
,hour_15 varchar
,hour_16 varchar
,hour_17 varchar)

如果您首先需要hour_0，则必须按o_hour订购。我引用manual on crosstab functions：

实际上，SQL查询应始终指定ORDER BY 1,2来确保输入行是否正确排序，即带有的值将相同的row_name放在一起并在其中正确排序行。

crosstab（）查询移位列

1 个答案: