数据库

 

MySQL Workbench建表时PK, NN, UQ, BIN, UN, ZF, AL的意思

- PK: primary key (column is part of a pk)  主键

- NN: not null (column is nullable)  是否为空

- UQ: unique (column is part of a unique key)  外键

- AI: auto increment (the column is auto incremented when rows are inserted)  自动增加

- BIN: binary (if dt is a blob or similar, this indicates that is binary data, rather than text)   二进制

- 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”) 

zerofill(n)
值中最有意义的n字节总为0，并且不保存。
http://dev.mysql.com/doc/refman/5.1/zh/client-side-scripts.html