docs: add docs

codeigniter4 · Dec 3, 2023 · 4307472 · 4307472
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diff --git a/user_guide_src/source/changelogs/v4.5.0.rst b/user_guide_src/source/changelogs/v4.5.0.rst
@@ -239,6 +239,20 @@ Database
 Query Builder
 -------------
 
+.. _v450-query-builder-limit-0-behavior:
+
+limit(0) Behavior
+^^^^^^^^^^^^^^^^^
+
+- Added a feature flag ``Feature::$limitZeroAsAll`` to fix the incorrect behavior
+  of ``limit(0)``.
+- If ``LIMIT 0`` is specified in a SQL statement, 0 records are returned. However,
+  there is a bug in the Query Builder, and if ``limit(0)`` is specified, the
+  generated SQL statement will have no ``LIMIT`` clause and all records will be
+  returned.
+- It is recommended that ``$limitZeroAsAll`` in **app/Config/Feature.php** be set
+  to ``false`` as this incorrect behavior will be fixed in a future version.
+
 Forge
 -----
 

diff --git a/user_guide_src/source/database/query_builder.rst b/user_guide_src/source/database/query_builder.rst
@@ -681,6 +681,14 @@ Lets you limit the number of rows you would like returned by the query:
 
 .. literalinclude:: query_builder/070.php
 
+.. note:: If ``LIMIT 0`` is specified in a SQL statement, 0 records are returned.
+  However, there is a bug in the Query Builder, and if ``limit(0)`` is specified,
+  the generated SQL statement will have no ``LIMIT`` clause and all records will
+  be returned. To fix the incorrect behavior, a setting was added in v4.5.0. See
+  :ref:`v450-query-builder-limit-0-behavior` for details. The incorrect behavior
+  will be fixed in a future version, so it is recommended that you change the
+  default setting.
+
 The second parameter lets you set a result offset.
 
 .. literalinclude:: query_builder/071.php

diff --git a/user_guide_src/source/installation/upgrade_450.rst b/user_guide_src/source/installation/upgrade_450.rst
@@ -260,6 +260,8 @@ Others
     - The default value of ``DBCollat`` in ``$default`` has been change to ``utf8mb4_general_ci``.
     - The default value of ``DBCollat`` in ``$tests`` has been change to ``''``.
 - app/Config/Feature.php
+    - ``Config\Feature::$limitZeroAsAll`` has been added. See
+      :ref:`v450-query-builder-limit-0-behavior`.
     - ``Config\Feature::$multipleFilters`` has been removed, because now
       :ref:`multiple-filters` are always enabled.
 - app/Config/Kint.php

diff --git a/user_guide_src/source/installation/upgrade_database.rst b/user_guide_src/source/installation/upgrade_database.rst
@@ -43,6 +43,7 @@ Upgrade Guide
     - ``$this->db->having('user_id',  45);`` to ``$builder->having('user_id',  45);``
 6. CI4 does not provide `Database Caching <https://www.codeigniter.com/userguide3/database/caching.html>`_
    layer known from CI3, so if you need to cache the result, use :doc:`../libraries/caching` instead.
+7. If you use ``limit(0)`` in Query Builder, CI4 returns all records in stead of no records due to a bug. But since v4.5.0, you can change the incorrect behavior with a setting. So change the setting. See :ref:`v450-query-builder-limit-0-behavior` for details.
 
 Code Example
 ============