由于count（column_name）而获取资源而不是数字

I'm trying to get the number of columns from a table :

$query = "select count(column_name) from information_schema.columns where table_name = '".$tableName."'";
$columns = pg_query($query);
echo $columns;

but instead of number I get a mysterious Resource id #61.
Converting to other types like string or int doesn't help.

pg_query returns a resource to the query result, to get the actual rows, you can use any of the pg_fetch_* functions, such as pg_fetch_assoc

All this is well documented on php.net/pg_query. Look at the functions' signature:

resource pg_query ([ resource $connection ], string $query )
//return type function name (params)

Hence, what you need is:

$result = pg_query($query);
$columns = pg_fetch_all($result);
var_dump($columns);

Also, please get into the habit of passing the connection resource to the pg_query call explicitly... there's no telling what connection you're using, when working on a sizeable project, with multiple connections.

pg_query() returns resource and it's correct behaviour. You can check it in manual (what you definitely should do anyway).

To get rows from that resource you can use functions like pg_fetch_all() or pg_fetch_row(). Read about both and decide which one will be better in that case.

You can try this

$query = "SHOW COLUMNS FROM '".$tableName."' ";
$result= pg_query($query);

if (!$result) {
  echo "An error occurred.
";
  exit;
}
$i = 1;
while ($row = pg_fetch_row($result)) {
  echo "Column[$i] names: ".$row[0]."";
  echo "<br />";
  $i++;
}

echo "Column Count: ".$i;