如何通过PHP知道哪些列在postgres中没有null约束？

Question

Im trying to build some html input elements via php in order to fill up rows in a postgres table.

I want to add the attribute "required" to some of the html input elements (those that correspond to the columns that have the NOT NULL constraint).

How can I know which columns have that constraint?

Answer 1

Using PDO (and suggestion here ), you should be able to pull it off as follows:

$q = $dbh->prepare("\d tablename");
$q->execute();
$table_fields = $q->fetchAll();
foreach ($table_fields as $field) {
    if (strpos($field['Modifiers'], 'not null') !== FALSE) {
         // this column ($field['Column']) has a "not null" constraint.
    }
}

Edit : same if you're dead set on using PostgreSQL PHP extension:

$q = pg_query("\d tablename");
while ($row = pg_fetch_array($result)) {
    if (strpos($row['Modifiers'], 'not null') !== FALSE) {
         // this column ($row['Column']) has a "not null" constraint.
    }
}

Answer 2

Use Pomm and it will perform those queries for you to inspect your database with the CLI:

$ php vendor/bin/pomm.php pomm:inspect:relation test pika_chu
Relation public.pika_chu
+----+---------------+--------+-----------------------------------------------+---------+---------+
| pk | name          | type   | default                                       | notnull | comment |
+----+---------------+--------+-----------------------------------------------+---------+---------+
| *  | pika_chu_id   | int4   | nextval('pika_chu_pika_chu_id_seq'::regclass) | yes     |         |
|    | some_data     | int4   |                                               | yes     |         |
|    | nullable_data | bpchar |                                               | no      |         |
+----+---------------+--------+-----------------------------------------------+---------+---------+