Like column
A suggested extension to MySQL
Like column
Create table t1 ( x int unsigned default 911, y like x )
Create table t2 (x like t1.x)
Tricky extension
Create table t2 (x always like t1.x)
Meaning that
alter table t1 modify x int signed
implies a corresponding alter on t2
The purpose of ‘LIKE’ is to avoid multiply specifying that which must always be the same. LIKE both documents the dependency, and eliminates the possibility of inconsistency. ALWAYS LIKE prevents the inconsistency developing in the future.