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

["David G. Johnston" <david.g.johnston@xxxxxxxxx>]

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

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