Question

我在Postgresql 10中的查询在GROUP子句中使用时引发错误

错误：函数string_agg（字符变化，未知，整数）确实不存在

我有at和atrelation表。 at具有唯一的ID和描述，而atrelation存储具有相关at和交易行ID的代码的多个交易。例如

id为6的产品行的列名称标签的值为service5％和contco4.5％

id为5的产品行的标签值为service5％

我需要显示2行，即第6行和第5行。

第5行显示列标记值'service5％和contco4.5％'

第6行显示列标记值“ service5％”

select  atrelation.id, 
        string_agg(at.description, ' and ' ) within GROUP (ORDER BY atrelation.id )  as tag1    
from  at, atrelation    
where atrelation.id = atrelation.atid   
group by atrelation.id    
order by atrelation.id desc;

上述查询引发以下错误

ERROR:  function string_agg(character varying, unknown, integer) does not exist
LINE 1: select atrelation.purchase_order_line_id as id, string_agg(a...
                                                        ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
********** Error **********

ERROR: function string_agg(character varying, unknown, integer) does not exist
SQL state: 42883
Hint: No function matches the given name and argument types. You might need to add explicit type casts.
Character: 49

Answer 1

您需要将ORDER BY放入函数调用中，并删除WITHIN GROUP部分：

string_agg(at.description, ' and ' ORDER BY atrelation.id)  as tag1

在postgresql中在GROUP中与string_agg一起使用时引发错误

1 个答案: