以下代码运行正常。但是我想将array ['a','b','c','d','e']定义为变量。
rows, err := db.Query("select colname from (SELECT date, unnest(array['a', 'b', 'c', 'd', 'e']) AS colname, unnest(array[a, b, c, d, e]) AS thing from test1 where date='123') as tester where thing=1;")
所以我尝试使用github.com/lib/pq遵循以下代码。
arr1 := []string{"a", "b", "c", "d", "e"}
rows, err := db.Query("select colname from (SELECT date, unnest($1) AS colname, unnest($1) AS thing from test1 where date='123') as tester where thing=1;", pq.Array(arr1))
但是出现诸如“ pq:函数unnest(未知)不是唯一的”之类的错误。 表结构和样本数据-
test=# \d+ test1
Table "public.test1"
Column | Type | Modifiers | Storage | Stats target | Description
--------+-----------------------+-----------+----------+--------------+-------------
a | character varying(10) | | extended | |
b | character varying(10) | | extended | |
c | character varying(10) | | extended | |
d | character varying(10) | | extended | |
e | character varying(10) | | extended | |
date | character varying(10) | | extended | |
test=# select * from test1 ;
a | b | c | d | e | date
---+---+---+---+---+------
3 | 1 | 3 | 2 | 3 | 124
3 | 3 | 2 | 2 | 1 | 125
1 | 2 | 2 | 1 | 3 | 126
1 | 2 | 3 | 2 | 3 | 127
1 | 1 | 2 | 2 | 3 | 123
(5 rows)
基本上我想要在任何特定日期具有值“ 1”的列名(a,b,c,d或e)。
答案 0 :(得分:2)
我猜想pq.Array
会以字符串形式给您一个PostgreSQL数组,因此您最终会得到这样的东西:
unnest('{a,b,c,d,e}')
,而PostgreSQL不确定应如何解释该字符串,因此抱怨unnest(unknown)
。您应该能够添加一个显式类型强制转换以清除问题:
unnest($1::text[]) -- PostgreSQL-specific casting syntax
unnest(cast($1 as text[])) -- Standard casting syntax
您最终会得到这样的东西:
rows, err := db.Query("select colname from (SELECT date, unnest($1::text[]) AS colname, unnest($1) AS thing from test1 where date='123') as tester where thing=1;", pq.Array(arr1))