出現錯誤“接近“（”：語法錯誤 sqlite 錯誤”

Question

我正在使用 sqlite 版本 3.21.0。

我在執行以下查詢時出錯。 pd 是熊貓庫。 看來這個命令是正確的。

此代碼使用 over(partition by Gender) 子句在 Person 表中獲取 Gender 及其各自的計數。

pd.read_sql_query(""" select Gender, Count(Gender) Over(Partition By Gender) CategoryCount from Person """,conn)

OperationalError                          Traceback (most recent call last)
~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\io\sql.py in execute(self, *args, **kwargs)
   1430             else:
-> 1431                 cur.execute(*args)
   1432             return cur

OperationalError: near "(": syntax error

During handling of the above exception, another exception occurred:

DatabaseError                             Traceback (most recent call last)
<ipython-input-42-e842fb9f3a5b> in <module>()
      1 pd.read_sql_query(""" select Gender, Count(Gender) Over(Partition By Gender) CategoryCount
----> 2                       from Person """,conn)

~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\io\sql.py in read_sql_query(sql, con, index_col, coerce_float, params, parse_dates, chunksize)
    312     return pandas_sql.read_query(
    313         sql, index_col=index_col, params=params, coerce_float=coerce_float,
--> 314         parse_dates=parse_dates, chunksize=chunksize)
    315 
    316 

~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\io\sql.py in read_query(self, sql, index_col, coerce_float, params, parse_dates, chunksize)
   1466 
   1467         args = _convert_params(sql, params)
-> 1468         cursor = self.execute(*args)
   1469         columns = [col_desc[0] for col_desc in cursor.description]
   1470 

~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\io\sql.py in execute(self, *args, **kwargs)
   1443                 "Execution failed on sql '{sql}': {exc}".format(
   1444                     sql=args[0], exc=exc))
-> 1445             raise_with_traceback(ex)
   1446 
   1447     @staticmethod

~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\compat\__init__.py in raise_with_traceback(exc, traceback)
    418         if traceback == Ellipsis:
    419             _, _, traceback = sys.exc_info()
--> 420         raise exc.with_traceback(traceback)
    421 else:
    422     # this version of raise is a syntax error in Python 3

~\AppData\Local\Continuum\anaconda3\lib\site-packages\pandas\io\sql.py in execute(self, *args, **kwargs)
   1429                 cur.execute(*args, **kwargs)
   1430             else:
-> 1431                 cur.execute(*args)
   1432             return cur
   1433         except Exception as exc:

DatabaseError: Execution failed on sql ' select Gender, Count(Gender) Over(Partition By Gender) CategoryCount
                      from Person ': near "(": syntax error

Answer 1

如果您使用的是不支持窗口函數的舊版 SQLite，您就會遇到這個問題。

在任何情況下，窗口函數在這里似乎都不合適。 我會推薦簡單的聚合：

select Gender, Count(*) as CategoryCount
from Person
group by Gender;

這將在Gender為每個值返回一行以及計數。

使用窗口函數，您將獲得Person所有行，其中只有Gender和 count —— 大概有更多的行和重復的數據。