51 SQLAlchemy屬性常用數據類型詳解 · Flask notebook

# 51 SQLAlchemy屬性常用數據類型詳解 * Integer:整型 * Float:浮點類型 * Boolean:傳遞True/False進去 * DECIMAL:定點類型，是專門為了解決浮點精度丟失的問題的，在存儲相關的字段的時候建議都是要這個數據字段，并且這個類型使用的時候需要傳遞兩個參數，第一個參數使用來標記字段能夠存儲多少個數字，第二個參數是表示小數點的最大位數 * enum:枚舉類型。指定某個字段只能是枚舉中指定的幾個值，不能為其他值，在ORM模型中，使用Enum來作為枚舉，示例代碼如下: ```text import enum class TagEnum(enum.Enum): python = "python" flask = "flask" django = "django" class Article(Base): __tablename__ = "article" id = Column(Integer,primary_key=True,autoincrement=True) # tag = Column(Enum('python','django','flask')) tag = Column(Enum(TagEnum)) # article = Article(tag='1') # article = Article(tag='python') article = Article(tag=TagEnum.python) ``` * Date:傳遞datetime.date\(\)進去。存儲時間，只能存儲年月日。映射到數據庫中是date類型。在python中，可以使用datetime.date來指定 ```text class Article(Base): __tablename__ = "article" id = Column(Integer,primary_key=True,autoincrement=True) create_time = Column(Date) from datetime import date article = Article(create_time=date(year=2017,month=10,day=8)) ``` * DateTime:傳遞datetime.datetime\(\)進去。存儲時間，可以存儲年月日時分秒毫秒等。映射到數據庫中也是datetime類型。在python代碼中，可以使用"datetime.datetime"來指定，示例 ```text class Article(Base): __tablename__ = "article" id = Column(Integer,primary_key=True,autoincrement=True) create_time = Column(DateTime) from datetime import datetime article = Article(create_time=datetime(year=2017,month=11,day=11,hour=11,minute=11,second=11,microsecond=11)) ``` * Time:傳遞datetime.time\(\)進去。存儲時間，可以存儲時分秒，映射到數據庫中也是time類型。在python代碼中，可以使用"datetime.time"來指定，示例\] ```text class Article(Base): __tablename__ = "article" id = Column(Integer,primary_key=True,autoincrement=True) create_time = Column(Time) from datetime import time article = Article(create_time=time(hour=11,minute=11,second=11,microsecond=11)) # article = Article(create_time=datetime.now()) ``` * String:字符類型，使用時需要指定長度，區別于Text類型 * Text:文本類型.存儲長字符串，一般可以存儲6w多個字符。如果超出了這個范圍，可以使用LONGTEXT類型，映射到數據庫中就是text類型 * LONGTEXT:長文本類型 ```text from sqlalchemy import create_engine,Column,String,Integer,Float,Boolean,DECIMAL,Enum,Date,DateTime,Time,Text from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.dialects.mysql import LONGTEXT from sqlalchemy.orm import sessionmaker HOSTNAME = '127.0.0.1' PORT = "3306" USERNAME = "root" PASSWORD = "123456" DATABASE = "xt_flask" DB_URI = "mysql+pymysql://{}:{}@{}:{}/{}?charset=utf8".format(USERNAME,PASSWORD,HOSTNAME,PORT,DATABASE) engine = create_engine(DB_URI) Base = declarative_base(engine) session = sessionmaker(engine)() import enum class TagEnum(enum.Enum): python = "python" flask = "flask" django = "django" class Article(Base): __tablename__ = "article" id = Column(Integer,primary_key=True,autoincrement=True) # price = Column(Float) # is_delete = Column(Boolean) # price = Column(DECIMAL(10,4)) # 10000,0001 # tag = Column(Enum('python','django','flask')) # tag = Column(Enum(TagEnum)) # create_time = Column(Date) # create_time = Column(DateTime) # create_time = Column(Time) # title = Column(Text) title = Column(LONGTEXT) # flask-migrate Base.metadata.drop_all() Base.metadata.create_all() # article = Article(price = 10.293) # article = Article(is_delete=True) # article = Article(price=99999.99999) # article = Article(tag='1') # article = Article(tag='python') # article = Article(tag=TagEnum.python) from datetime import date from datetime import datetime from datetime import time # article = Article(create_time=date(year=2017,month=10,day=8)) # article = Article(create_time=datetime(year=2017,month=11,day=11,hour=11,minute=11,second=11,microsecond=11)) # article = Article(create_time=time(hour=11,minute=11,second=11,microsecond=11)) article = Article(title="angle") session.add(article) session.commit() ```