What do column flags mean in MySQL Workbench?
PK - Primary Key
NN - Not Null
BIN - Binary (stores data as binary strings. There is no character set so sorting and comparison is based on the numeric values of the bytes in the values.)
UN - Unsigned (non-negative numbers only. so if the range is -500 to 500, instead its 0 - 1000, the range is the same but it starts at 0)
UQ - Create/remove Unique Key
ZF - Zero-Filled (if the length is 5 like INT(5) then every field is filled with 0’s to the 5th digit. 12 = 00012, 400 = 00400, etc. )
AI - Auto Increment
G - Generated column. i.e. value generated by a formula based on the other columns
Here is the source of these column flags
http://dev.mysql.com/doc/workbench/en/wb-table-editor-columns-tab.html
This exact question is answered on mySql workbench-faq:
Hover over an acronym to view a description, and see the Section 8.1.11.2, “The Columns Tab” and MySQL CREATE TABLE documentation for additional details.
That means hover over an acronym in the mySql Workbench table editor.