我有这个带有准备语句的查询:
SELECT * FROM ONLY service_services
UNION ALL
SELECT * FROM fleet.service_services
WHERE deleted=false
ORDER BY $1
LIMIT $2
我将 name ASC
的值发送到 $1
并将 10
的值发送到 $2
出于某种原因,我收到此错误:
could not identify an ordering operator for type unknown
如果我硬编码 name ASC
而不是 $1,像这样:
SELECT * FROM ONLY service_services
UNION ALL
SELECT * FROM fleet.service_services
WHERE deleted=false
ORDER BY name ASC
LIMIT $1
它工作正常。
我做错了什么?
最佳答案
对于一列,您可以使用 CASE WHEN
对其进行参数化:
SELECT * FROM ONLY service_services
UNION ALL
SELECT * FROM fleet.service_services
WHERE deleted=false
ORDER BY
CASE WHEN $1 = 'name' THEN name
WHEN $1 = 'col_name' THEN col_name
ELSE ...
END
LIMIT $2;
或:
SELECT * FROM ONLY service_services
UNION ALL
SELECT * FROM fleet.service_services
WHERE deleted=false
ORDER BY
CASE $1
WHEN 'name' THEN name
WHEN 'col_name' THEN col_name
ELSE column_name -- default sorting
END
LIMIT $2;
使用 CASE
,您不需要将列转换为相同的数据类型以避免隐式转换错误。
编辑:
SELECT sub.*
FROM (
SELECT * FROM ONLY service_services
UNION ALL
SELECT * FROM fleet.service_services
WHERE deleted=false
) As sub
ORDER BY
CASE $1
WHEN 'name' THEN name
WHEN 'col_name' THEN col_name
ELSE column_name -- default sorting
END
LIMIT $2;
关于sql - Postgres : Could not identify an ordering operator for type unknown,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33802385/