On 2024-07-03 07:13:47 -0700, Rich Shepard wrote:
> On Wed, 3 Jul 2024, David G. Johnston wrote:
> > Yeah, the simply cast suggested will not work. You’d have to apply an
> > expression that turns the current contents into an array. The current
> > contents are not likely to be an array literal.
>
> David,
>
> No, it's not now an array.
>
> I thought that this expression would work, but it doesn't:
> bustrac=# alter table people alter column email set data type varchar(64)[] using email::varchar(64)[];
> RROR: malformed array literal: "frank@xxxxxxxxx"
> DETAIL: Array value must start with "{" or dimension information.
>
> If I correctly understand the error detail I'd need to change the contents
> of that column for all 1280 rows to enclose the contents in curly braces
> before I can convert the datatype to an array. Is that correct?
No. You need *some* way of creating an array with a single element which
is your email address. Constructing a valid array literal as a text and
casting that to array type is one way to do this. However, it seems like
a rather cumbersome and error-prone way to me.
As Raymond Hettinger likes to say: "There must be a better way".
And indeed, https://www.postgresql.org/docs/current/functions-array.html
shows lots of array values written as ARRAY[1, 2, 3] or similar. So that
makes it likely that ARRAY[email] creates an array with the intended
contents.
Try it with
select array[email] from people;
If that looks promising, you can use it in an alter table statement
(Torsten already posted the solution, but I wanted to expand a bit on
how to find it).
hp
--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp@xxxxxx | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"
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