On Tue, 4 Jun 2019 at 18:30, Lou <[email protected]> wrote:
> Hi everyone,
>
> Is it possible to convert a boolean yes or no field to hold a one letter
> string? For example, the strings: 's' 'f' 'p' 'e'
>
> To start off, I just need to convert true to 's'. false will have to be
> manually changed to 'f' or 'p' or 'e' as appropriate.
>
> Lou
>
Certainly you can.
origin=# create table foo (id serial primary key, name text, tfvalue
boolean);
CREATE TABLE
origin=# alter table foo alter column tfvalue set data type character;
ALTER TABLE
Perfectly fine if the table has no values in that column.
But wait, maybe not...
origin=# create table foo (id serial primary key, name text, tfvalue
boolean);
CREATE TABLE
origin=# insert into foo (name, tfvalue) values ('chris', 'true');
INSERT 0 1
origin=# insert into foo (name, tfvalue) values ('dave', 'false');
INSERT 0 1
origin=# insert into foo (name) values ('brad');
INSERT 0 1
origin=# alter table foo alter column tfvalue set data type character;
ERROR: value too long for type character(1)
Nope, you can't do that if there's data in the table.
This seems like an altogether terrible idea, actually. If you need a new
column with a totally different interpretation, you should probably create
a totally new column, that way you can do whatever you wish to the new
column.
Might want to consult the trusty documentation, too. <
https://www.postgresql.org/docs/9.5/datatype-boolean.html>
--
When confronted by a difficult problem, solve it by reducing it to the
question, "How would the Lone Ranger handle this?"
