使用 mysql 常量的 sqlalchemy 语法

Question

所以我正在尝试使用 SECOND 常量作为第一个参数来调用 mysql 函数 TIMEDATEDIFF [=] =14=]

    query = session.query(func.TIME(Log.IncidentDetection).label('detection'), func.TIMESTAMPDIFF(SECOND,Log.IncidentDetection, Log.IncidentClear).label("duration")).all()
    print(query)

我尝试将其作为字符串，但出现 mysql/mariadb 错误：

query = session.query(func.TIME(Log.IncidentDetection).label('detection'), func.TIMESTAMPDIFF("SECOND",Log.IncidentDetection, Log.IncidentClear).label("duration")).all()
print(query)

给我这个

sqlalchemy.exc.ProgrammingError: (mysql.connector.errors.ProgrammingError) 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ''SECOND', log.`IncidentDetection`, log.`IncidentClear`) AS duration 
FROM log' at line 1 [SQL: 'SELECT TIME(log.`IncidentDetection`) AS detection, TIMESTAMPDIFF(%(TIMESTAMPDIFF_1)s, log.`IncidentDetection`, log.`IncidentClear`) AS duration \nFROM log'] [parameters: {'TIMESTAMPDIFF_1': 'SECOND'}]

我确定它很简单，某种转义序列或我缺少的导入。我查看了 sqlalchemy 文档但无济于事。

Answer 1

为了让 sqlalchemy 将字符串准确解析为查询，我使用了 _literal_as_text() 函数

工作解决方案

from sqlalchemy.sql.expression import func, _literal_as_text
# ...
query = session.query(func.TIME(Log.IncidentDetection).label('detection'), func.TIMESTAMPDIFF(_literal_as_text("SECOND"),Log.IncidentDetection, Log.IncidentClear).label("duration")).all()
print(query)

使用 mysql 常量的 sqlalchemy 语法

sqlalchemy syntax for using mysql constants

python

mysql

sqlalchemy

func

literals