Check constraints for varchar[] and varchar[][] columns in a table

On Fri, Mar 4, 2016 at 6:59 AM, Alexander Farber <alexander.farber@gmail.com

wrote:

Hello,

for a Scrabble-like word game using PostgreSQL 9.5 as backend
I am trying to add CHECK constraints to the VARCHAR arrays:

CREATE TABLE words_games (
gid SERIAL PRIMARY KEY,
created timestamptz NOT NULL,

player1 integer REFERENCES words_users(uid) ON DELETE CASCADE NOT
NULL,
player2 integer REFERENCES words_users(uid) ON DELETE CASCADE,

played1 timestamptz,
played2 timestamptz,

hand1 varchar[7] NOT NULL CHECK (ALL(hand1) ~ '^[*A-Z]$'),
hand2 varchar[7] NOT NULL CHECK (ALL(hand2) ~ '^[*A-Z]$'),
pile varchar[116] NOT NULL CHECK (ALL(pile) ~ '^[*A-Z]$'),

board varchar[15][15] NOT NULL CHECK (ALL(board) ~ '^[.A-Z]$'),
style integer NOT NULL CHECK (1 <= style AND style <= 4)
);

but get syntax errors near "ALL"

ERROR: syntax error at or near "ALL"
LINE 8: hand1 varchar[7] NOT NULL CHECK (ALL(hand1) ~ '^[A-Z...
^
- probably because that keyword is supposed to be on the right side?

Could anyone please recommend a way to implement check constraints here?

​Google'd: postgresql regexp array matching
Found:
http://stackoverflow.com/questions/22098706/how-to-use-regular-expression-with-any-array-operator

The custom operator is the most direct solution - and meets this need quite
well - the array-taking function is overkill for this though has the
benefit of being more explicit and it can expanded upon to do things a
simple operator cannot.

David J.
​

Alexander Farber <alexander.farber@gmail.com> writes:

I am trying to add CHECK constraints to the VARCHAR arrays:

hand1 varchar[7] NOT NULL CHECK (ALL(hand1) ~ '^[*A-Z]$'),

but get syntax errors near "ALL"
- probably because that keyword is supposed to be on the right side?

Yeah, the syntax has to be "scalar operator ALL (array)".

Could anyone please recommend a way to implement check constraints here?

The workaround that's been suggested in the past is to define a reversed
pattern match operator, ie one that has the pattern on the left. There's
no such thing in the core PG distribution, but the only hard part of making
your own is figuring out what to name the operator ;-)

regards, tom lane

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Okay, let's call it <~

:-)

On Fri, Mar 4, 2016 at 4:53 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: