Question

我的第一张表是：

ID | Code   | Description
1  | IT     | Informatics
2  | GAM    | Gamer
3  | PROG   | Programmer

我的第二张表格如下：

ID | Order  | Catcod
1  | 8080   | {IT,GAM}
2  | 7051   | 
3  | 5601   | PROG

请注意＆＃34;代码＆＃34;第一个表中的列是Varchar列，第二个表中的Catcod列是Varchar []列。

我尝试执行的SQL是：

SELECT *
FROM table2 RIGHT OUTER JOIN
     table1 
     ON table2.Catcod = table1.Code

我得到的错误是：

ERROR:  operator does not exist: character varying[] = character varying
LINE 4:  RIGHT OUTER JOIN gc1pbcat on gc1vrkordhdr.catcod = gc1pbcat...
                                                          ^
HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.
********** Error **********

ERROR: operator does not exist: character varying[] = character varying
SQL state: 42883
Hint: No operator matches the given name and argument type(s). You might need to add explicit type casts.
Character: 216

有没有人知道如何将Varchar []转换为只是Varchar，或者可能拆分数组？

因为我想在表2中的Varchar []中显示Catcode的描述。

更新

或者有人知道我如何将Varchar []转换为Varchar？

Answer 1

使用LEFT JOIN和any()：

SELECT *
    FROM table2
    LEFT JOIN table1 on table1.code = any(table2.catcod);

 id | order |  catcod  | id | code | description 
----+-------+----------+----+------+-------------
  1 |  8080 | {IT,GAM} |  1 | IT   | InfOrmatics
  1 |  8080 | {IT,GAM} |  2 | GAM  | GaMer
  2 |  7051 |          |    |      | 
  3 |  5601 | {PROG}   |  3 | PROG | PRogrammer
(4 rows)

如果您想为订单添加一行，请使用string_agg()，例如：

SELECT table2.id, table2.order, string_agg(description, ', ') description
    FROM table2
    LEFT JOIN table1 on table1.code = any(table2.catcod) 
GROUP BY 1, 2;

 id | order |    description     
----+-------+--------------------
  1 |  8080 | InfOrmatics, GaMer
  2 |  7051 | 
  3 |  5601 | PRogrammer
(3 rows)

尝试加入另一个表时出现Postgres错误，导致错误

1 个答案: