Select elements of unknown array type

[e-letter <inpost@xxxxxxxxx>]

Readers,

A query result using:

"
$databasequery=pg_query($databaseconnection,"SELECT * FROM
postgresqltable WHERE columnname='$phpvariable'");
...
while($databasequery1=pg_fetch_assoc($databasequery)){
        var_dump ($databasequery1);     
        }
...
"

Web browser display:
"
array(13) {["databasecolumnname"]=>string(...)"databasetuple"
...
}
"

Please could someone advise why this output is produced and relevant
part(s) of the manual to read.