Solution to PHP Fatal error: Call to undefined function pg_connect()

PHP is a widely used server-side scripting language for building web applications. PostgreSQL is a popular open source relational database management system. When using a PostgreSQL database, you usually need to use a PostgreSQL extension in PHP. However, sometimes you encounter an error, namely "PHP Fatal error: Call to undefined function pg_connect()", and you need to solve this problem to proceed smoothly.

So, what should you do if you encounter this error when using PostgreSQL in PHP? This article will introduce you to several methods to solve this problem.

Method 1: Install PHP Postgresql extension

First, you need to confirm whether your PHP has the PostgreSQL extension installed. If it is not installed, you need to install the extension first.

If your PHP version is 5.3 and above, you can use the PECL tool to install the PostgreSQL extension. Open the terminal and enter the following command:

sudo pecl install pdo_pgsql

If your PHP version is lower than 5.3, you can use the following command to install it:

sudo apt-get install php5-pgsql

After installation, if you are using the Apache server, you need to restart Apache to take effect.

Method 2: Check the php.ini file

If you have installed the PostgreSQL extension and encountered the error "PHP Fatal error: Call to undefined function pg_connect()", then you You need to check whether the php.ini file is configured correctly.

First, find the path where the php.ini file is located. Normally, the php.ini file is located in the /etc/php.ini or /etc/php5/apache2/php.ini path. You can use the following command to find it in the terminal:

sudo find / -name "php.ini"

After that, open the php.ini file and find the following line of code:

;extension=pgsql.so

Remove the preceding comment symbol ";" so that it becomes :

extension=pgsql.so

Then, save and close the php.ini file. If you are using an Apache server, you need to restart Apache for it to take effect.

Method 3: Check whether the PostgreSQL service has been started

If you have installed the PostgreSQL extension and the php.ini file has been configured correctly, but still encounter "PHP Fatal error: Call to undefined function pg_connect()" error, then you need to check whether the PostgreSQL service has been started.

Normally, the PostgreSQL service will start automatically when the operating system starts. You can use the following command to check whether the PostgreSQL service is running:

sudo service postgresql status

If the PostgreSQL service is not running, you can use the following command to start the service:

sudo service postgresql start

Also, if you are running on another machine For PostgreSQL database, you need to specify the IP address, port number, user name, password and other information of the database server in the PHP code. You can use the following PHP code to test the connection to the database:

$conn = pg_connect("host=localhost port=5432 dbname=mydatabase user=myusername password=mypassword");

If the connection is successful, it means that you have solved the "PHP Fatal error: Call to undefined function pg_connect()" problem.

Summary:

"PHP Fatal error: Call to undefined function pg_connect()" This error is usually caused by PHP being unable to find the PostgreSQL extension or by incorrect configuration in the php.ini file. You can solve this problem by installing the PostgreSQL extension, checking the php.ini file configuration, and checking whether the PostgreSQL service is started. If you haven't solved this error by following the above methods, you can consult the PHP technical forum or PHP development community to get more help.

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