Bring back the AFTER clause for DB Forge add_column()

(it was temporarily removed due to multiple inconsistencies with other drivers)

This commit also fixes issue #1988.
Also added support for the FIRST clause (again, MySQL and CUBRID only).

3 files changed, 52 insertions, 6 deletions

diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index f3509d00a..792969cf4 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -168,7 +168,8 @@ Release Date: Not Released
    -  :doc:`Database Forge <database/forge>` changes include:
 	 - Added an optional second parameter to ``drop_table()`` that allows adding the **IF EXISTS** condition, which is no longer the default.
 	 - Added support for passing a custom database object to the loader.
-	 - Removed the optional AFTER clause from method ``add_column()``.
+	 - Deprecated ``add_column()``'s third method. *AFTER* clause should now be added to the field definition array instead.
+	 - Added support for usage of the *FIRST* clause in ``add_column()`` for MySQL and CUBRID.
 	 - Overall improved support for all of the drivers.
    -  :doc:`Database Utility <database/utilities>` chages include:
 	 - Added support for passing a custom database object to the loader.
diff --git a/user_guide_src/source/database/forge.rst b/user_guide_src/source/database/forge.rst
index de5748b45..ca904ed00 100644
--- a/user_guide_src/source/database/forge.rst
+++ b/user_guide_src/source/database/forge.rst
@@ -231,7 +231,7 @@ Modifying Tables
 ****************
 
 $this->dbforge->add_column()
-=============================
+============================
 
 The ``add_column()`` method is used to modify an existing table. It
 accepts the same field array as above, and can be used for an unlimited
@@ -243,10 +243,25 @@ number of additional fields.
 		'preferences' => array('type' => 'TEXT')
 	);
 	$this->dbforge->add_column('table_name', $fields); 
-	// gives ALTER TABLE table_name ADD preferences TEXT
+	// Executes: ALTER TABLE table_name ADD preferences TEXT
+
+If you are using MySQL or CUBIRD, then you can take advantage of their
+AFTER and FIRST clauses to position the new column.
+
+Examples::
+
+	// Will place the new column after the `another_field` column:
+	$fields = array(
+		'preferences' => array('type' => 'TEXT', 'after' => 'another_field')
+	);
+
+	// Will place the new column at the start of the table definition:
+	$fields = array(
+		'preferences' => array('type' => 'TEXT', 'first' => TRUE)
+	);
 
 $this->dbforge->drop_column()
-==============================
+=============================
 
 Used to remove a column from a table.
 
@@ -256,7 +271,7 @@ Used to remove a column from a table.
 
 
 $this->dbforge->modify_column()
-================================
+===============================
 
 The usage of this method is identical to ``add_column()``, except it
 alters an existing column rather than adding a new one. In order to
diff --git a/user_guide_src/source/installation/upgrade_300.rst b/user_guide_src/source/installation/upgrade_300.rst
index 2bfb1bdbf..0af21b11e 100644
--- a/user_guide_src/source/installation/upgrade_300.rst
+++ b/user_guide_src/source/installation/upgrade_300.rst
@@ -284,4 +284,34 @@ should write '-' instead of 'dash' and '_' instead of 'underscore'.
 in CodeIgniter 3.1+.
 
 .. note:: These options are still available, but you're strongly encouraged to remove their usage
-	sooner rather than later.
\ No newline at end of file
+	sooner rather than later.
+
+Database Forge method add_column() with an AFTER clause
+=======================================================
+
+If you have used the **third parameter** for :doc:`Database Forge <database/forge>` method
+``add_column()`` to add a field for an AFTER clause, then you should change its usage.
+
+That third parameter has been deprecated and scheduled for removal in CodeIgniter 3.1+.
+
+You should now put AFTER clause field names in the field definition array instead::
+
+	// Old usage:
+	$field = array(
+		'new_field' => array('type' => 'TEXT')
+	);
+
+	$this->dbforge->add_column('table_name', $field, 'another_field');
+
+	// New usage:
+	$field = array(
+		'new_field' => array('type' => 'TEXT', 'after' => 'another_field')
+	);
+
+	$this->dbforge->add_column('table_name', $field);
+
+.. note:: The parameter is still available, but you're strongly encouraged to remove its usage
+	sooner rather than later.
+
+.. note:: This is for MySQL and CUBRID databases only! Other drivers don't support this
+	clause and will silently ignore it.