When we define a table in Oracle we may define the columns as:
当我们在Oracle中定义表时，我们可以将列定义为：
"NAME" VARCHAR2(80) NOT NULL ENABLE
My question is I could not understand the meaning of "ENABLE" in this statement. What would be the difference if we just define as "NAME" VARCHAR2(80) NOT NULL ?
我的问题是我无法理解本声明中“ENABLE”的含义。如果我们只定义为“NAME”VARCHAR2（80）NOT NULL会有什么区别？
1 个解决方案
#1
31
ENABLE is the default state, so leaving it out has the same effect. The opposite would be to specify DISABLE, in which case the constraint would not be active.
ENABLE是默认状态，因此将其保留为具有相同的效果。相反的是指定DISABLE，在这种情况下约束不会是活动的。
See the constraint documentation for more information.
有关更多信息，请参阅约束文档。
#1
31
ENABLE is the default state, so leaving it out has the same effect. The opposite would be to specify DISABLE, in which case the constraint would not be active.
ENABLE是默认状态，因此将其保留为具有相同的效果。相反的是指定DISABLE，在这种情况下约束不会是活动的。
See the constraint documentation for more information.
有关更多信息，请参阅约束文档。