# pg_parameter_status

(PHP 5, PHP 7, PHP 8)

pg_parameter_status — Looks up a current parameter setting of the server

### 说明

pg_parameter_status(PgSql\Connection `$connection` = ?, string `$param_name`): string

Looks up a current parameter setting of the server.

Certain parameter values are reported by the server automatically at connection startup or whenever their values change. pg_parameter_status() can be used to interrogate these settings. It returns the current value of a parameter if known, or `false` if the parameter is not known.

Parameters reported as of PostgreSQL 8.0 include `server_version`, `server_encoding`, `client_encoding`, `is_superuser`, `session_authorization`, `DateStyle`, `TimeZone`, and `integer_datetimes`. (`server_encoding`, `TimeZone`, and `integer_datetimes` were not reported by releases before 8.0.) Note that `server_version`, `server_encoding` and `integer_datetimes` cannot change after PostgreSQL startup.

PostgreSQL 7.3 or lower servers do not report parameter settings, pg_parameter_status() includes logic to obtain values for `server_version` and `client_encoding` anyway. Applications are encouraged to use pg_parameter_status() rather than ad hoc code to determine these values.

警告

On a pre-7.4 PostgreSQL server, changing `client_encoding` via `SET` after connection startup will not be reflected by pg_parameter_status().

### 参数

`connection`

  An PgSql\Connection instance. When `connection` is unspecified, the default connection is used. The default connection is the last connection made by pg_connect() or pg_pconnect().

  警告

  As of PHP 8.1.0, using the default connection is deprecated.

`param_name`

  Possible `param_name` values include `server_version`, `server_encoding`, `client_encoding`, `is_superuser`, `session_authorization`, `DateStyle`, `TimeZone`, and `integer_datetimes`. Note that this value is case-sensitive.

### 返回值

A string containing the value of the parameter, `false` on failure or invalid `param_name`.

### 更新日志

版本 | 说明
--- | ---
8.1.0 | 现在 `connection` 参数接受 PgSql\Connection 实例，之前接受 resource。

### 示例

示例 #1 pg_parameter_status() example

`<?php
$dbconn = pg_connect("dbname=publisher") or die("Could not connect");
echo "Server encoding: ", pg_parameter_status($dbconn, "server_encoding");
?>`

以上示例会输出：

    Server encoding: SQL_ASCII

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