sql 查询空值

查询值为 null 的数据,sql 语句:

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> SELECT * FROM user_model WHERE tel IS NULL;
> SELECT * FROM user_model WHERE tel IS not NULL;

sqlalchemy 语句:

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> user_list = user_model.query.filter(UserModel.tel!=None).all()
> user_list = user_model.query.filter(UserModel.tel==None).all()
> user_list = user_model.query.filter(UserModel.tel.is_(None)).all()
> user_list = user_model.query.filter_by(tel=None).all()