mysql 的使用（1）

mysql workbench创建表时columns中

       PK: primary key (column is part of a pk)  主关键字
       NN: not null (column is nullable)   不能为空
       BIN: binary (if dt is a blob or similar, this indicates that is binary data, rather than text)   二进制
       UQ: unique (column is part of a unique key)     唯一的
       UN: unsigned (for integer types, see docs: “10.2. Numeric Types”)
        ZF: zero fill (rather a display related flag, see docs: “10.2. Numeric Types”)
       AI: auto increment (the column is auto incremented when rows are inserted)   自动加数