diff --git a/main/install/migrate-db-1.8.6.1-1.8.6.2-pre.sql b/main/install/migrate-db-1.8.6.1-1.8.6.2-pre.sql
new file mode 100755
index 0000000000..e46138e5b0
--- /dev/null
+++ b/main/install/migrate-db-1.8.6.1-1.8.6.2-pre.sql
@@ -0,0 +1,28 @@
+-- This script updates the databases structure before migrating the data from
+-- version 1.8.6.1 to version 1.8.6.2
+-- it is intended as a standalone script, however, because of the multiple
+-- databases related difficulties, it should be parsed by a PHP script in
+-- order to connect to and update the right databases.
+-- There is one line per query, allowing the PHP function file() to read
+-- all lines separately into an array. The xxMAINxx-type markers are there
+-- to tell the PHP script which database we're talking about.
+-- By always using the keyword "TABLE" in the queries, we should be able
+-- to retrieve and modify the table name from the PHP script if needed, which
+-- will allow us to deal with the unique-database-type installations
+--
+-- This first part is for the main database
+-- xxMAINxx
+ALTER TABLE gradebook_evaluation ADD COLUMN type varchar(40) NOT NULL;
+
+-- xxSTATSxx
+
+-- xxUSERxx
+
+-- xxCOURSExx
+
+ALTER TABLE quiz ADD COLUMN session_id smallint DEFAULT 0, ADD INDEX (session_id);
+ALTER TABLE blog ADD COLUMN session_id smallint DEFAULT 0, ADD INDEX (session_id);
+ALTER TABLE course_description ADD COLUMN session_id smallint DEFAULT 0, ADD INDEX (session_id);
+ALTER TABLE glossary ADD COLUMN session_id smallint DEFAULT 0, ADD INDEX (session_id);
+ALTER TABLE link ADD COLUMN session_id smallint DEFAULT 0, ADD INDEX (session_id);
+ALTER TABLE wiki ADD COLUMN session_id smallint DEFAULT 0, ADD INDEX (session_id);