pg_fetch_result()

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

从结果资源中返回值

说明

pg_fetch_result(resource $result,int $row, mixed $field): mixed

pg_fetch_result()根据由pg_query()返回的$result资源返回相应的值。$row为整型数。$field为字段名（字符串）或字段索引（整数）。$row和$field指明了查询结果中的哪个单元被返回。行编号从 0 开始。除了用字段名之外，还可以用不带引号的数字作为字段索引。字段索引从 0 开始。

PostgreSQL 有很多内置的类型，这里只直接支持基本类型。所有形式的integer，boolean和 void 类型都被返回为integer值。所有形式的 float 和 real 类型都被返回为float值。Boolean 类型被返回为"t"或者"f"。所有其它类型包括数组都被返回为字符串，该字符串的格式和默认的 PostgreSQL 风格一样，可以在psql程序中看到。

Please note that a very old bug (#76548) has been fixed in 7.2.8.
Previously, pg_fetch_result did not fetch the next row if $row was omitted.
It is now well the case, so bad use of the function can now cause some bugs in your codes.

Comment on boolean fields:
If you retrieve a boolean value from the PostgreSQL database, be aware that the value returned will be either the character 't' or the character 'f', not an integer. So, the statement
   if (pg_fetch_result($rsRecords,0,'blnTrueFalseField')) {
    echo "TRUE";
   } else {
    echo "FALSE";
   }
will echo "TRUE" in either case (True or False stored in the field). In order to work as expected, do this instead:
   if (pg_fetch_result($rsRecords,0,'blnTrueFalseField') == 't') {
    echo "TRUE";
   } else {
    echo "FALSE";
   }

See bug #33809 http://bugs.php.net/bug.php?id=33809
Whether this really is a bug or a feature is not clear.
However, it is probably best to always put your column names in extra quotes.
$res = pg_query(...);
$colname = pg_field_name($res, $j);
pg_fetch_result($res, $i, "\"$colname\"");

In order to use upper case in pg_fetch_result column names, it is apparently necessary to include explicit quotation marks.
Thus when I do this sort of thing:
$res = pg_query(...);
$ncols = pg_num_fields($res);
for ($j = 0; $j < $ncols; ++$j) {
  $colname[$j] = pg_field_name($res, $j);
  $name = htmlspecialchars($colname[$j]);
  print("Column $j name = \"$name\"\n");
  $value = htmlspecialchars(pg_fetch_result($res, 0, $colname[$j]));
  print("Column \"{$colname[$j]}\" value = \"$value\"\n");
  }
I get this sort of thing:
[....]
Warning: pg_fetch_result() [function.pg-fetch-result]: Bad column offset specified in /.../view.php on line 247
Column 8 name = "VEC index"
Column "VEC index" value = ""
But if I change the $value line to this:
$value = htmlspecialchars(pg_fetch_result($res, 0, "\"$colname[$j]\""));
I get this:
[...]
Column 8 name = "VEC index"
Column "VEC index" value[0] = "47"
In my opinion, pg_fetch_result(...) should use the quotes already. In other words, this may be a bug in the PHP postgres library. It does not seem to be a documented feature of pg_fetch_result() although the postgresql manual documents it under "SQL syntax", "Lexical structure".
PHP version 5.1.4.
psql version 8.1.4.

Use can use pg_fetch_result when getting a value (like a smallint as in this example) returned by your stored procedure 
<?php
$pgConnection = pg_connect("dbname=users user=me");
$userNameToCheckFor = "metal";
$result = pg_query($pgConnection, "SELECT howManyUsersHaveThisName('$userNameToCheckFor')");
$count = pg_fetch_result($result, 0, 'howManyUsersHaveThisName');
?>