sql - hstore:无法连接两个 hstore 值

Question

Postgres 新手，使用 v9.3，想利用 hstore。

当我尝试连接两个 hstore 值时，出现奇怪的错误:

SELECT p.properties->'name' || p.properties->'age' FROM people p where p.id=1;

错误是:

ERROR:  operator does not exist: text -> unknown
LINE 1: select n.properties->'name' || n.properties->'age' from n...
                                                   ^
HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.

我也试过了，没关系:

SELECT p.properties->'name'::text || p.properties->'age'::text FROM people p where p.id=1;

不过，我可以做

SELECT p.properties->'name' FROM people p where p.id=1;

SELECT p.properties->'age' FROM people p where p.id=1;

难道不能将同一个 hstore 中的两个 hstore 值连接起来吗？

感谢任何指点!

Answer 1

您可以按原样使用 CAST 函数:

SELECT CAST(p.properties->'name' AS text) || CAST(p.properties->'age' AS text) FROM people p where p.id=1;