diff --git a/rector.php b/rector.php
index 29755dc2647a..ca19dcebc12b 100644
--- a/rector.php
+++ b/rector.php
@@ -144,6 +144,7 @@
         ClassPropertyAssignToConstructorPromotionRector::class => [
             __DIR__ . '/system/Database/BaseResult.php',
             __DIR__ . '/system/Database/RawSql.php',
+            __DIR__ . '/system/Database/Exceptions/DatabaseException.php',
             __DIR__ . '/system/Debug/BaseExceptionHandler.php',
             __DIR__ . '/system/Filters/Filters.php',
             __DIR__ . '/system/HTTP/CURLRequest.php',
diff --git a/system/Database/BaseConnection.php b/system/Database/BaseConnection.php
index ca1acd1d6be7..b7b94a2ae40e 100644
--- a/system/Database/BaseConnection.php
+++ b/system/Database/BaseConnection.php
@@ -219,6 +219,14 @@ abstract class BaseConnection implements ConnectionInterface
      */
     protected $lastQuery;
 
+    /**
+     * The exception that would have been thrown on the last failed query
+     * if DBDebug were enabled. Null when the last query succeeded or when
+     * DBDebug is true (in which case the exception is thrown directly and
+     * this property is never set).
+     */
+    protected ?DatabaseException $lastException = null;
+
     /**
      * Connection ID
      *
@@ -698,8 +706,9 @@ public function query(string $sql, $binds = null, bool $setEscapeFlags = true, s
 
         // Run the query for real
         try {
-            $exception      = null;
-            $this->resultID = $this->simpleQuery($query->getQuery());
+            $exception           = null;
+            $this->lastException = null;
+            $this->resultID      = $this->simpleQuery($query->getQuery());
         } catch (DatabaseException $exception) {
             $this->resultID = false;
         }
@@ -737,11 +746,7 @@ public function query(string $sql, $binds = null, bool $setEscapeFlags = true, s
                 Events::trigger('DBQuery', $query);
 
                 if ($exception instanceof DatabaseException) {
-                    throw new DatabaseException(
-                        $exception->getMessage(),
-                        $exception->getCode(),
-                        $exception,
-                    );
+                    throw $exception;
                 }
 
                 return false;
@@ -1847,6 +1852,17 @@ public function isWriteType($sql): bool
      */
     abstract public function error(): array;
 
+    /**
+     * Returns the exception that would have been thrown on the last failed
+     * query if DBDebug were enabled. Returns null if the last query succeeded
+     * or if DBDebug is true (in which case the exception is always thrown
+     * directly and this method will always return null).
+     */
+    public function getLastException(): ?DatabaseException
+    {
+        return $this->lastException;
+    }
+
     /**
      * Insert ID
      *
diff --git a/system/Database/Exceptions/DatabaseException.php b/system/Database/Exceptions/DatabaseException.php
index 77b170e0b407..48e335095910 100644
--- a/system/Database/Exceptions/DatabaseException.php
+++ b/system/Database/Exceptions/DatabaseException.php
@@ -15,9 +15,34 @@
 
 use CodeIgniter\Exceptions\HasExitCodeInterface;
 use CodeIgniter\Exceptions\RuntimeException;
+use Throwable;
 
 class DatabaseException extends RuntimeException implements ExceptionInterface, HasExitCodeInterface
 {
+    /**
+     * Native code returned by the database driver.
+     */
+    protected int|string $databaseCode = 0;
+
+    /**
+     * @param int|string $code Native database code (e.g. 1062, 23505, 23000/2601)
+     */
+    public function __construct(string $message = '', int|string $code = 0, ?Throwable $previous = null)
+    {
+        $this->databaseCode = $code;
+
+        // Keep Throwable::getCode() behavior BC-friendly for non-int DB codes.
+        parent::__construct($message, is_int($code) ? $code : 0, $previous);
+    }
+
+    /**
+     * Returns the native code from the database driver.
+     */
+    public function getDatabaseCode(): int|string
+    {
+        return $this->databaseCode;
+    }
+
     public function getExitCode(): int
     {
         return EXIT_DATABASE;
diff --git a/system/Database/Exceptions/UniqueConstraintViolationException.php b/system/Database/Exceptions/UniqueConstraintViolationException.php
new file mode 100644
index 000000000000..148a0e0bc9bf
--- /dev/null
+++ b/system/Database/Exceptions/UniqueConstraintViolationException.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Exceptions;
+
+class UniqueConstraintViolationException extends DatabaseException
+{
+}
diff --git a/system/Database/MySQLi/Connection.php b/system/Database/MySQLi/Connection.php
index 2339469dfc71..3dbc29e4d442 100644
--- a/system/Database/MySQLi/Connection.php
+++ b/system/Database/MySQLi/Connection.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
 use CodeIgniter\Database\TableName;
 use CodeIgniter\Exceptions\LogicException;
 use mysqli;
@@ -317,9 +318,16 @@ protected function execute(string $sql)
                 'trace'   => render_backtrace($e->getTrace()),
             ]);
 
+            // MySQL error 1062: ER_DUP_ENTRY – duplicate key value
+            $exception = $e->getCode() === 1062
+                ? new UniqueConstraintViolationException($e->getMessage(), $e->getCode(), $e)
+                : new DatabaseException($e->getMessage(), $e->getCode(), $e);
+
             if ($this->DBDebug) {
-                throw new DatabaseException($e->getMessage(), $e->getCode(), $e);
+                throw $exception;
             }
+
+            $this->lastException = $exception;
         }
 
         return false;
diff --git a/system/Database/OCI8/Connection.php b/system/Database/OCI8/Connection.php
index bbed63526336..2e28ddca501f 100644
--- a/system/Database/OCI8/Connection.php
+++ b/system/Database/OCI8/Connection.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
 use CodeIgniter\Database\Query;
 use CodeIgniter\Database\TableName;
 use ErrorException;
@@ -236,10 +237,27 @@ protected function execute(string $sql)
 
             oci_set_prefetch($this->stmtId, 1000);
 
-            $result          = oci_execute($this->stmtId, $this->commitMode) ? $this->stmtId : false;
+            $result = oci_execute($this->stmtId, $this->commitMode) ? $this->stmtId : false;
+
+            if ($result === false) {
+                // ORA-00001: unique constraint violated
+                $error     = $this->error();
+                $exception = $error['code'] === 1
+                    ? new UniqueConstraintViolationException((string) $error['message'], $error['code'])
+                    : new DatabaseException((string) $error['message'], $error['code']);
+
+                if ($this->DBDebug) {
+                    throw $exception;
+                }
+
+                $this->lastException = $exception;
+
+                return false;
+            }
+
             $insertTableName = $this->parseInsertTableName($sql);
 
-            if ($result && $insertTableName !== '') {
+            if ($insertTableName !== '') {
                 $this->lastInsertedTableName = $insertTableName;
             }
 
@@ -254,9 +272,17 @@ protected function execute(string $sql)
                 'trace'   => render_backtrace($trace),
             ]);
 
+            // ORA-00001: unique constraint violated
+            $error     = $this->error();
+            $exception = $error['code'] === 1
+                ? new UniqueConstraintViolationException((string) $error['message'], $error['code'], $e)
+                : new DatabaseException((string) $error['message'], $error['code'], $e);
+
             if ($this->DBDebug) {
-                throw new DatabaseException($e->getMessage(), $e->getCode(), $e);
+                throw $exception;
             }
+
+            $this->lastException = $exception;
         }
 
         return false;
@@ -615,25 +641,25 @@ protected function bindParams($params)
      */
     public function error(): array
     {
-        // oci_error() returns an array that already contains
-        // 'code' and 'message' keys, but it can return false
-        // if there was no error ....
-        $error     = oci_error();
+        // oci_error() is resource-specific: check each resource in priority order
+        // and return the first one that actually has an error. This ensures that
+        // e.g. oci_parse() failures (error on connID) are found even when stmtId
+        // holds a stale valid resource from the previous successful query.
         $resources = [$this->cursorId, $this->stmtId, $this->connID];
 
         foreach ($resources as $resource) {
             if (is_resource($resource)) {
                 $error = oci_error($resource);
-                break;
+
+                if (is_array($error)) {
+                    return $error;
+                }
             }
         }
 
-        return is_array($error)
-            ? $error
-            : [
-                'code'    => '',
-                'message' => '',
-            ];
+        $error = oci_error();
+
+        return is_array($error) ? $error : ['code' => '', 'message' => ''];
     }
 
     public function insertID(): int
diff --git a/system/Database/Postgre/Connection.php b/system/Database/Postgre/Connection.php
index 11b48c474ee5..5dbdbbf30d64 100644
--- a/system/Database/Postgre/Connection.php
+++ b/system/Database/Postgre/Connection.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
 use CodeIgniter\Database\RawSql;
 use CodeIgniter\Database\TableName;
 use ErrorException;
@@ -88,6 +89,12 @@ public function connect(bool $persistent = false)
                 throw new DatabaseException($error);
             }
 
+            // Use verbose errors so that pg_last_error() always includes the
+            // 5-character SQLSTATE code, enabling reliable error classification
+            // (e.g. '23505' for unique constraint violations) without needing
+            // to parse ambiguous English-language message strings.
+            pg_set_error_verbosity($this->connID, PGSQL_ERRORS_VERBOSE);
+
             if (! empty($this->schema)) {
                 $this->simpleQuery("SET search_path TO {$this->schema},public");
             }
@@ -203,7 +210,27 @@ public function getVersion(): string
     protected function execute(string $sql)
     {
         try {
-            return pg_query($this->connID, $sql);
+            $result = pg_query($this->connID, $sql);
+
+            if ($result === false) {
+                $error = $this->error();
+
+                log_message('error', (string) $error['message']);
+
+                $exception = $error['code'] === '23505'
+                    ? new UniqueConstraintViolationException((string) $error['message'], $error['code'])
+                    : new DatabaseException((string) $error['message'], $error['code']);
+
+                if ($this->DBDebug) {
+                    throw $exception;
+                }
+
+                $this->lastException = $exception;
+
+                return false;
+            }
+
+            return $result;
         } catch (ErrorException $e) {
             $trace = array_slice($e->getTrace(), 2); // remove the call to error handler
 
@@ -214,9 +241,19 @@ protected function execute(string $sql)
                 'trace'   => render_backtrace($trace),
             ]);
 
+            // pg_last_error() is still populated after an ErrorException,
+            // so we can use error() here to get the reliable SQLSTATE code.
+            $error = $this->error();
+
+            $exception = $error['code'] === '23505'
+                ? new UniqueConstraintViolationException((string) $error['message'], $error['code'], $e)
+                : new DatabaseException((string) $error['message'], $error['code'], $e);
+
             if ($this->DBDebug) {
-                throw new DatabaseException($e->getMessage(), $e->getCode(), $e);
+                throw $exception;
             }
+
+            $this->lastException = $exception;
         }
 
         return false;
@@ -479,12 +516,33 @@ protected function _enableForeignKeyChecks()
      */
     public function error(): array
     {
+        // pg_set_error_verbosity(PGSQL_ERRORS_VERBOSE) is set during connect(),
+        // so pg_last_error() includes the SQLSTATE code in the format:
+        // "ERROR: 23505: duplicate key value violates unique constraint ..."
+        $message = pg_last_error($this->connID);
+
         return [
-            'code'    => '',
-            'message' => pg_last_error($this->connID),
+            'code'    => $this->extractSqlState($message),
+            'message' => $message,
         ];
     }
 
+    /**
+     * Extracts the 5-character SQLSTATE code from a PostgreSQL error message.
+     *
+     * With pg_set_error_verbosity(PGSQL_ERRORS_VERBOSE) set in connect(),
+     * pg_last_error() always returns the verbose format:
+     * "ERROR: 23505: duplicate key value violates unique constraint ..."
+     */
+    private function extractSqlState(string $message): string
+    {
+        if (preg_match('/\bERROR:\s*([0-9A-Z]{5})\s*:/', $message, $match) === 1) {
+            return $match[1];
+        }
+
+        return '';
+    }
+
     /**
      * @return int|string
      */
diff --git a/system/Database/SQLSRV/Connection.php b/system/Database/SQLSRV/Connection.php
index 76dd80bdb09f..98b9d77b09c4 100644
--- a/system/Database/SQLSRV/Connection.php
+++ b/system/Database/SQLSRV/Connection.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
 use CodeIgniter\Database\TableName;
 use stdClass;
 
@@ -519,24 +520,51 @@ protected function execute(string $sql)
             : sqlsrv_query($this->connID, $sql, [], ['Scrollable' => $this->scrollable]);
 
         if ($stmt === false) {
-            $trace = debug_backtrace();
-            $first = array_shift($trace);
+            $trace   = debug_backtrace();
+            $first   = array_shift($trace);
+            $message = $this->getAllErrorMessages();
 
             log_message('error', "{message}\nin {exFile} on line {exLine}.\n{trace}", [
-                'message' => $this->getAllErrorMessages(),
+                'message' => $message,
                 'exFile'  => clean_path($first['file']),
                 'exLine'  => $first['line'],
                 'trace'   => render_backtrace($trace),
             ]);
 
+            $error     = $this->error();
+            $exception = $this->isUniqueConstraintViolation()
+                ? new UniqueConstraintViolationException($message, $error['code'])
+                : new DatabaseException($message, $error['code']);
+
             if ($this->DBDebug) {
-                throw new DatabaseException($this->getAllErrorMessages());
+                throw $exception;
             }
+
+            $this->lastException = $exception;
         }
 
         return $stmt;
     }
 
+    private function isUniqueConstraintViolation(): bool
+    {
+        $errors = sqlsrv_errors(SQLSRV_ERR_ERRORS);
+        if (! is_array($errors)) {
+            return false;
+        }
+
+        foreach ($errors as $error) {
+            // SQLSTATE 23000 (integrity constraint violation) with SQL Server error
+            // 2627 (UNIQUE CONSTRAINT or PRIMARY KEY violation) or 2601 (UNIQUE INDEX violation).
+            if (($error['SQLSTATE'] ?? '') === '23000'
+                && in_array($error['code'] ?? 0, [2627, 2601], true)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Returns the last error encountered by this connection.
      *
diff --git a/system/Database/SQLite3/Connection.php b/system/Database/SQLite3/Connection.php
index 3865669a9e2d..4f2faa0c82eb 100644
--- a/system/Database/SQLite3/Connection.php
+++ b/system/Database/SQLite3/Connection.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
 use CodeIgniter\Database\TableName;
 use CodeIgniter\Exceptions\InvalidArgumentException;
 use Exception;
@@ -170,14 +171,30 @@ protected function execute(string $sql)
                 'trace'   => render_backtrace($e->getTrace()),
             ]);
 
+            $error     = $this->error();
+            $exception = $this->isUniqueConstraintViolation($e->getMessage())
+                ? new UniqueConstraintViolationException($e->getMessage(), $error['code'], $e)
+                : new DatabaseException($e->getMessage(), $error['code'], $e);
+
             if ($this->DBDebug) {
-                throw new DatabaseException($e->getMessage(), $e->getCode(), $e);
+                throw $exception;
             }
+
+            $this->lastException = $exception;
         }
 
         return false;
     }
 
+    private function isUniqueConstraintViolation(string $message): bool
+    {
+        // SQLite3 reports unique violations in two formats depending on version:
+        // Modern:  "UNIQUE constraint failed: table.column"
+        // Legacy:  "column X is not unique"
+        return str_contains($message, 'UNIQUE constraint failed')
+            || str_contains($message, 'is not unique');
+    }
+
     /**
      * Returns the total number of rows affected by this query.
      */
diff --git a/tests/system/Database/DatabaseExceptionTest.php b/tests/system/Database/DatabaseExceptionTest.php
new file mode 100644
index 000000000000..43dfca1b92e8
--- /dev/null
+++ b/tests/system/Database/DatabaseExceptionTest.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database;
+
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Test\CIUnitTestCase;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * @internal
+ */
+#[Group('Others')]
+final class DatabaseExceptionTest extends CIUnitTestCase
+{
+    public function testIntCodeIsAvailableViaGetCodeAndGetDatabaseCode(): void
+    {
+        $exception = new DatabaseException('error', 1062);
+
+        $this->assertSame(1062, $exception->getCode());
+        $this->assertSame(1062, $exception->getDatabaseCode());
+    }
+
+    public function testStringCodeIsAvailableViaGetDatabaseCodeWithoutAffectingGetCode(): void
+    {
+        $exception = new DatabaseException('error', '23505');
+
+        $this->assertSame(0, $exception->getCode());
+        $this->assertSame('23505', $exception->getDatabaseCode());
+    }
+
+    public function testStringCodeWithSlashIsAvailableViaGetDatabaseCode(): void
+    {
+        $exception = new DatabaseException('error', '23000/2601');
+
+        $this->assertSame(0, $exception->getCode());
+        $this->assertSame('23000/2601', $exception->getDatabaseCode());
+    }
+}
diff --git a/tests/system/Database/Live/ExecuteLogMessageFormatTest.php b/tests/system/Database/Live/ExecuteLogMessageFormatTest.php
index ca79e4f46fcc..7e12c1f48c50 100644
--- a/tests/system/Database/Live/ExecuteLogMessageFormatTest.php
+++ b/tests/system/Database/Live/ExecuteLogMessageFormatTest.php
@@ -48,7 +48,7 @@ public function testLogMessageWhenExecuteFailsShowFullStructuredBacktrace(): voi
 
         $pattern = match ($db->DBDriver) {
             'MySQLi'  => '/Table \'test\.some_table\' doesn\'t exist/',
-            'Postgre' => '/pg_query\(\): Query failed: ERROR:  relation "some_table" does not exist/',
+            'Postgre' => '/pg_query\(\): Query failed: ERROR:  42P01: relation "some_table" does not exist/',
             'SQLite3' => '/Unable to prepare statement:\s(\d+,\s)?no such table: some_table/',
             'OCI8'    => '/oci_execute\(\): ORA-00942: table or view does not exist/',
             'SQLSRV'  => '/\[Microsoft\]\[ODBC Driver \d+ for SQL Server\]\[SQL Server\]Invalid object name \'some_table\'/',
@@ -59,7 +59,7 @@ public function testLogMessageWhenExecuteFailsShowFullStructuredBacktrace(): voi
         $this->assertMatchesRegularExpression($pattern, array_shift($messageFromLogs));
 
         if ($db->DBDriver === 'Postgre') {
-            $messageFromLogs = array_slice($messageFromLogs, 2);
+            $messageFromLogs = array_slice($messageFromLogs, 3);
         } elseif ($db->DBDriver === 'OCI8') {
             $messageFromLogs = array_slice($messageFromLogs, 1);
         }
diff --git a/tests/system/Database/Live/Postgre/ConnectTest.php b/tests/system/Database/Live/Postgre/ConnectTest.php
index d616a60b968c..b15944187e98 100644
--- a/tests/system/Database/Live/Postgre/ConnectTest.php
+++ b/tests/system/Database/Live/Postgre/ConnectTest.php
@@ -40,7 +40,7 @@ public function testShowErrorMessageWhenSettingInvalidCharset(): void
         $this->expectException(DatabaseException::class);
         $this->expectExceptionMessage(
             'Unable to connect to the database.
-Main connection [Postgre]: ERROR:  invalid value for parameter "client_encoding": "utf8mb4"',
+Main connection [Postgre]: ERROR:  22023: invalid value for parameter "client_encoding": "utf8mb4"',
         );
 
         $config = config('Database');
diff --git a/tests/system/Database/Live/UniqueConstraintViolationTest.php b/tests/system/Database/Live/UniqueConstraintViolationTest.php
new file mode 100644
index 000000000000..0a436f079b88
--- /dev/null
+++ b/tests/system/Database/Live/UniqueConstraintViolationTest.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Live;
+
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
+use CodeIgniter\Test\CIUnitTestCase;
+use CodeIgniter\Test\DatabaseTestTrait;
+use PHPUnit\Framework\Attributes\Group;
+use Tests\Support\Database\Seeds\CITestSeeder;
+
+/**
+ * @internal
+ */
+#[Group('DatabaseLive')]
+final class UniqueConstraintViolationTest extends CIUnitTestCase
+{
+    use DatabaseTestTrait;
+
+    protected $refresh = true;
+    protected $seed    = CITestSeeder::class;
+
+    protected function tearDown(): void
+    {
+        $this->enableDBDebug();
+
+        parent::tearDown();
+    }
+
+    public function testThrowsUniqueConstraintViolationExceptionWithDebugEnabled(): void
+    {
+        $this->enableDBDebug();
+
+        $this->expectException(UniqueConstraintViolationException::class);
+
+        // 'derek@world.com' is already seeded in the user table
+        $this->db->table('user')->insert([
+            'name'    => 'Duplicate',
+            'email'   => 'derek@world.com',
+            'country' => 'US',
+        ]);
+    }
+
+    public function testReturnsFalseAndErrorIsPopulatedWithDebugDisabled(): void
+    {
+        $this->disableDBDebug();
+
+        // 'derek@world.com' is already seeded in the user table
+        $result = $this->db->table('user')->insert([
+            'name'    => 'Duplicate',
+            'email'   => 'derek@world.com',
+            'country' => 'US',
+        ]);
+
+        $this->assertFalse($result);
+
+        $error = $this->db->error();
+
+        $expectedCode = match ($this->db->DBDriver) {
+            'MySQLi'  => 1062,
+            'Postgre' => '23505',
+            'SQLite3' => 19,
+            'SQLSRV'  => '23000/2627',
+            'OCI8'    => 1,
+            default   => $this->fail('No expected error code defined for DB driver: ' . $this->db->DBDriver),
+        };
+
+        $this->assertSame($expectedCode, $error['code']);
+        $this->assertNotEmpty($error['message']);
+
+        $exception = $this->db->getLastException();
+        $this->assertInstanceOf(UniqueConstraintViolationException::class, $exception);
+        $this->assertSame($expectedCode, $exception->getDatabaseCode());
+    }
+}
diff --git a/user_guide_src/source/changelogs/v4.8.0.rst b/user_guide_src/source/changelogs/v4.8.0.rst
index 95e306063380..2f8b7071a56f 100644
--- a/user_guide_src/source/changelogs/v4.8.0.rst
+++ b/user_guide_src/source/changelogs/v4.8.0.rst
@@ -24,6 +24,7 @@ Behavior Changes
 ================
 
 - **Commands:** The ``filter:check`` command now requires the HTTP method argument to be uppercase (e.g., ``spark filter:check GET /`` instead of ``spark filter:check get /``).
+- **Database:** The Postgre driver now sets ``PGSQL_ERRORS_VERBOSE`` on connect. Error messages returned by ``$db->error()['message']``, thrown exceptions, and log entries now include the 5-character SQLSTATE code (e.g., ``ERROR:  42P01: relation "x" does not exist`` instead of ``ERROR:  relation "x" does not exist``). Code that matches against exact Postgre error message strings may need updating.
 
 Interface Changes
 =================
@@ -123,6 +124,9 @@ Others
 ------
 
 - Added new ``timezone`` option to connection array in ``Config\Database`` config. This ensures consistent timestamps between model operations and database functions like ``NOW()``. Supported drivers: **MySQLi**, **Postgre**, and **OCI8**. See :ref:`database-config-timezone` for details.
+- Added :php:class:`UniqueConstraintViolationException <CodeIgniter\\Database\\Exceptions\\UniqueConstraintViolationException>` which extends ``DatabaseException`` and is thrown on duplicate key (unique constraint) violations across all database drivers. See :ref:`database-unique-constraint-violation`.
+- Added ``$db->getLastException()`` which returns the typed exception even when ``DBDebug`` is ``false``. See :ref:`database-get-last-exception`.
+- Added ``DatabaseException::getDatabaseCode()`` returning the native driver error code as ``int|string``; ``getCode()`` is constrained to ``int`` by PHP's ``Throwable`` interface and cannot carry string SQLSTATE codes.
 
 Model
 =====
diff --git a/user_guide_src/source/database/queries.rst b/user_guide_src/source/database/queries.rst
index 4a07b4ba8295..8109399ee25c 100644
--- a/user_guide_src/source/database/queries.rst
+++ b/user_guide_src/source/database/queries.rst
@@ -203,15 +203,63 @@ placeholders in the query:
 Handling Errors
 ***************
 
+.. note:: It is strongly recommended to keep ``DBDebug`` set to ``true``
+    (the default). This ensures all query failures surface immediately as
+    exceptions, preventing silent data corruption. Setting it to ``false``
+    is considered legacy behaviour and may be deprecated in a future version.
+
+DBDebug Enabled (Recommended)
+=============================
+
+When :ref:`DBDebug <database-config-explanation-of-values>` is ``true``
+(the default), any query failure throws a ``DatabaseException`` or one of
+its subclasses, which you can catch and handle:
+
+.. literalinclude:: queries/030.php
+
+.. _database-unique-constraint-violation:
+
+UniqueConstraintViolationException
+----------------------------------
+
+.. versionadded:: 4.8.0
+
+``UniqueConstraintViolationException`` extends ``DatabaseException`` and is
+thrown specifically when a query fails due to a duplicate key or unique
+constraint violation. Catching it separately allows you to handle this case
+without inspecting raw driver-specific error codes.
+
+DBDebug Disabled
+================
+
+When ``DBDebug`` is ``false``, query failures return ``false`` instead of
+throwing. Two methods are available to inspect what went wrong.
+
 $db->error()
-============
+------------
 
-If you need to get the last error that has occurred, the ``error()`` method
-will return an array containing its code and message. Here's a quick
-example:
+The ``error()`` method returns an array with ``code`` and ``message`` keys
+describing the last error. Error codes are driver-specific (an **int** for
+MySQLi, SQLite3, and OCI8; a SQLSTATE **string** for Postgre and SQLSRV):
 
 .. literalinclude:: queries/015.php
 
+.. _database-get-last-exception:
+
+$db->getLastException()
+-----------------------
+
+.. versionadded:: 4.8.0
+
+``getLastException()`` returns the typed exception that would have been
+thrown had ``DBDebug`` been ``true``. This is the recommended way to
+distinguish between failure types (e.g., a unique constraint violation vs.
+another database error) without enabling ``DBDebug``:
+
+.. literalinclude:: queries/031.php
+
+.. note:: ``getLastException()`` is reset to ``null`` at the start of every
+    query. Inspect it immediately after the failed operation.
 
 ****************
 Prepared Queries
diff --git a/user_guide_src/source/database/queries/030.php b/user_guide_src/source/database/queries/030.php
new file mode 100644
index 000000000000..a4fea00892f0
--- /dev/null
+++ b/user_guide_src/source/database/queries/030.php
@@ -0,0 +1,12 @@
+<?php
+
+use CodeIgniter\Database\Exceptions\DatabaseException;
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
+
+try {
+    $db->table('users')->insert(['email' => 'duplicate@example.com']);
+} catch (UniqueConstraintViolationException $e) {
+    // Duplicate key — handle gracefully
+} catch (DatabaseException $e) {
+    // Other database error
+}
diff --git a/user_guide_src/source/database/queries/031.php b/user_guide_src/source/database/queries/031.php
new file mode 100644
index 000000000000..4dafb880cd5f
--- /dev/null
+++ b/user_guide_src/source/database/queries/031.php
@@ -0,0 +1,9 @@
+<?php
+
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
+
+$inserted = $db->table('users')->insert(['email' => 'duplicate@example.com']);
+
+if (! $inserted && $db->getLastException() instanceof UniqueConstraintViolationException) {
+    // Handle duplicate key violation
+}
diff --git a/user_guide_src/source/general/errors.rst b/user_guide_src/source/general/errors.rst
index 2a79f5a33425..46bc3773f531 100644
--- a/user_guide_src/source/general/errors.rst
+++ b/user_guide_src/source/general/errors.rst
@@ -204,6 +204,18 @@ or when it is temporarily lost:
 
 This provides an exit code of 8.
 
+UniqueConstraintViolationException
+----------------------------------
+
+.. versionadded:: 4.8.0
+
+``UniqueConstraintViolationException`` extends ``DatabaseException`` and is thrown when a query
+fails due to a duplicate key or unique constraint violation. It is supported by all database drivers.
+
+.. literalinclude:: errors/019.php
+
+See :ref:`database-unique-constraint-violation` for full usage details.
+
 RedirectException
 -----------------
 
diff --git a/user_guide_src/source/general/errors/019.php b/user_guide_src/source/general/errors/019.php
new file mode 100644
index 000000000000..d30592009bfe
--- /dev/null
+++ b/user_guide_src/source/general/errors/019.php
@@ -0,0 +1,9 @@
+<?php
+
+use CodeIgniter\Database\Exceptions\UniqueConstraintViolationException;
+
+try {
+    $db->table('users')->insert(['email' => 'duplicate@example.com']);
+} catch (UniqueConstraintViolationException $e) {
+    // Handle duplicate key violation
+}