Where can I read about the behavior of the postgress casting operators?
-
20-02-2021 - |
Question
I want to do something like this:
alter table foos
alter column bar type bool using bar::boolean;
bar
is currently a text column. Some experimentation shows that postgres will do things like convert a string "t"
to boolean true
. In my case this is great, but I'd like to read the full behavior before using this. I can't seem to find where this documentation is.
Solution
The behavior for boolean
typically you have to go look up every type and to see how it can be cast or look for a function to do the casting
here is a link
Postgresql also supports Create Cast
Information on the pg_cast
OTHER TIPS
This is in the PostgreSQL manual section on the boolean data type:
Boolean constants can be represented in SQL queries by the SQL key words
TRUE
,FALSE
, andNULL
.The datatype input function for type
boolean
accepts these string representations for the “true” state:true yes on 1
and these representations for the “false” state:
false no off 0
Unique prefixes of these strings are also accepted, for example
t
orn
. Leading or trailing whitespace is ignored, and case does not matter.The datatype output function for type
boolean
always emits eithert
orf
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