(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
pg_last_error — Get the last error message string of a connection
   pg_last_error() returns the last error message
   for a given connection. 
  
Error messages may be overwritten by internal PostgreSQL (libpq) function calls. It may not return an appropriate error message if multiple errors occur inside a PostgreSQL module function.
Use pg_result_error(), pg_result_error_field(), pg_result_status() and pg_connection_status() for better error handling.
Note:
This function used to be called pg_errormessage().
connectionAn PgSql\Connection instance.
When connection is null, the default connection is used.
The default connection is the last connection made by pg_connect()
or pg_pconnect().
As of PHP 8.1.0, using the default connection is deprecated.
   A string containing the last error message on the 
   given connection.
  
| Version | Description | 
|---|---|
| 8.1.0 | The connectionparameter expects an PgSql\Connection
  instance now; previously, a resource was expected. | 
| 8.0.0 | connectionis now nullable. | 
Example #1 pg_last_error() example
<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");
  // Query that fails
  $res = pg_query($dbconn, "select * from doesnotexist");
  
  echo pg_last_error($dbconn);
?>