简单的"WHERE"查询出错

Question

我在实例化视图中创建新列时遇到问题。我正在尝试创建此列，以便当预期点击率列中的行="平均"时，它将返回该行中有多少展示次数的计算。 据我所知，一切都是相应地设置的。 但是，我收到以下错误消息。

ERROR:  syntax error at or near "clickthrough"
LINE 2: SELECT SUM("Impressions" * 1 ) WHERE Expected clickthrough r...
^
********** Error **********
ERROR: syntax error at or near "clickthrough"
SQL state: 42601
Character: 94

在我看来，我在这里所做的任何不同变体最终都会出现类似的错误消息。

有谁知道这个问题的解决方案？ 整个查询是错误的吗？

CREATE MATERIALIZED VIEW adwords_calculated AS
SELECT SUM("Impressions" * 1 ) WHERE Expected clickthrough rate = "Average" 
AS Average Clickthrough Rate   
from adwords_initial;

当前列

Impressions| Expected clickthrough rate
-----------+----------------------------
1          |--
66         |--
12         |Average
13         |--
1000       |Above Average
45         |Average
4          |Below Average

愿望结果

Impressions| Expected clickthrough rate |Average Clickthrough Rate
-----------+----------------------------+-----------------
1          |--                          |0
66         |--                          |0
12         |Average                     |12
13         |--                          |0
1000       |Above Average               |0
45         |Average                     |45
4          |Below Average               |0

最终结果，(注释中为每个请求添加的其他列。

Impressions| Expected clickthrough rate |Average CTR| Country
-----------+----------------------------+-----------+----------
1          |--                          |0          |USA 
66         |--                          |0          |Germany
12         |Average                     |12         |Austria
13         |--                          |0          |UK
1000       |Above Average               |0          |China
45         |Average                     |45         |USA
4          |Below Average               |0          |Germany

Answer 1

如果您确实需要这样的列名，则必须使用双引号对它们进行转义。字符串文本必须括在单引号中。此外，子句的顺序是错误的。它应该是

SELECT expression AS alias
FROM table
WHERE condition;