postgresql - 为什么 POSTGRESQL 的 row_number() 窗口函数在 psycopg2 中不起作用，但在命令行或 pgadmin 中起作用？

Question

我有以下查询来找出特定数据的行号。

cursor.execute("select row_number from (select row_number() over(order by date desc), * from contest where date <= %s order by date LIMIT (select count(*) from contest where date <= %s) - 1) as new WHERE date = %s", (today, today ,date))

当我执行这个查询时，我得到这个错误信息

psycopg2.ProgrammingError
psycopg2.ProgrammingError: syntax error at or near "select"
LINE 1: select row_number from (select row_number() over(order by d...

然后我在 pgadmin4 或 postgresql 命令行中执行相同的查询，如下所示。它工作正常。

select row_number from (select row_number() over(order by date desc), * from contest where date <= '2017-5-5' order by date LIMIT (select count(*) from contest where date <='2017-5-5' ) - 1) as new WHERE date = '2017-2-1'

我使用最新版本的 postgresql 和 psycopg2。

我被困在这里了。我找不到答案。 我需要一些帮助。

Answer 1

虽然我不知道您的查询试图做什么，但没有语法错误并且它有效，当我从它创建 SSCCE 时:

import psycopg2, datetime

conn = psycopg2.connect("")
cursor = conn.cursor()

cursor.execute("create temporary table contest(id serial primary key, date date not null)")
cursor.execute("insert into contest (date) values (%s)", ("2000-01-01",))

today = datetime.date.today()
date = today-datetime.timedelta(days=1)
cursor.execute("""
    select row_number from (
        select row_number() over(order by date desc), *
        from contest
        where date <= %s
        order by date
        LIMIT ( select count(*) from contest where date <= %s) - 1
    ) as new
    WHERE date = %s""",
    (today, today, date)
)

适用于 Python-3.5/psycopg2-2.7.1 和 Python-2.7/psycopg2-2.6.2。问题似乎出在其他地方。