In MySQL Workbench table editor there are 7 column flags available: PK, NN, UQ, BIN, UN, ZF, AI.
PK obviously stands for Primary Key. What about others?
+3
A:
PK - Primary Key
NN - Not Null
BIN - Binary
UN - Unsigned
UQ - Create/remove Unique Key
ZF - Zero-Filled
AI - Auto Incremenent
vdeych
2010-09-08 01:19:25
Now why can't they just say that? Why is the unix world so obsessed with acronyms you have to memorize or look up?
BlueRaja - Danny Pflughoeft
2010-09-08 01:21:44
Could you be so kind to explain how does UQ work?
Ivan
2010-09-08 01:24:22
@Ivan: A unique constraint ensures that a value can only ever exist in the column *once*. Any attempt to add a duplicate will result in an unique data constraint error. The unique constraint as supports covering more than one column - this is called a composite.
OMG Ponies
2010-09-08 01:38:53
@Ivan -- it is a way to help index values while preventing duplicates. For example -- e-mail and SSN fields for a unique list of customers should be a unique index, since you frequently do lookups using those fields and they shouldn't repeat. For arbitrary values used only by your database internally for frequent lookups (such as customer ID), you should use a primary key with an auto-increment option instead.
vdeych
2010-09-08 01:46:24