完整性约束
NOT NULL: Disallows nulls (empty entries) in a table’s column.
UNIQUE KEY: Disallows duplicate values in a column or set of columns.
PRIMARY KEY: Disallows duplicate values and nulls in a column or set of
columns.
FOREIGN KEY: Requires each value in a column or set of columns to match a
value in a related table’s UNIQUE or PRIMARY KEY. FOREIGN KEY integrity
constraints also define referential integrity actions that dictate what Oracle
should do with dependent data if the data it references is altered.
CHECK: Disallows values that do not satisfy the logical expression of the
constraint.
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/58174/viewspace-660675/ ，如需转载，请注明出处，否则将追究法律责任。
