from sqlalchemy.orm import Query
from sqlalchemy.sql.functions import coalesce
from util import Base, session
class PrinterControl(Base):
__tablename__ = "printercontrol"
user_id = Column(String(10))
printer_name = Column(String(4), nullable=False, primary_key=True)
printer_description = Column(String(40), nullable=False)
user_name = "leea"
user_printer = Query([PrinterControl
]).filter(PrinterControl.user_id == user_name)
s = session.query(PrinterControl).filter(
case([(user_printer.exists(), PrinterControl.user_id == user_name)],
else_=(PrinterControl.user_id == None)))
[print(s.printer_name) for s in s]
# 集計関数がNULLを返すことを利用する
anonymous_printer = Query([func.min(PrinterControl.printer_name)])\
.filter(PrinterControl.user_id == None).as_scalar()
s = session.query(coalesce(func.min(PrinterControl.printer_name), anonymous_printer))\
.filter(PrinterControl.user_id == user_name)
[print(s) for s in s]
from sqlalchemy.orm import Query
from sqlalchemy.sql.functions import coalesce
from util import Base, session
class PrinterControl(Base):
__tablename__ = "printercontrol"
user_id = Column(String(10))
printer_name = Column(String(4), nullable=False, primary_key=True)
printer_description = Column(String(40), nullable=False)
user_name = "leea"
user_printer = Query([PrinterControl]).filter(PrinterControl.user_id == user_name)
s = session.query(PrinterControl).filter(case(
[(user_printer.exists(), PrinterControl.user_id == user_name)],
else_=(PrinterControl.user_id == None))
)
[print(s.printer_name) for s in s]
# 集計関数がNULLを返すことを利用する
anonymous_printer = Query([func.min(PrinterControl.printer_name)])\
.filter(PrinterControl.user_id == None).as_scalar()
s = session.query(coalesce(func.min(PrinterControl.printer_name), anonymous_printer))\
.filter(PrinterControl.user_id == user_name)
[print(s) for s in s]
