chore: import upstream snapshot with attribution

examples/mysql json handling/index.sql

@@ -0,0 +1,35 @@
+select 'form' as component, 'Create a new Group' as title, 'Create' as validate;
+select 'Name' as name;
+
+insert into groups(name) select :Name where :Name is not null;
+
+select 'list' as component, 'Groups' as title, 'No group yet' as empty_title;
+select name as title from groups;
+
+select 'form' as component, 'Add a user' as title, 'Add' as validate;
+select 'UserName' as name, 'Name' as label;
+select 
+    'Memberships[]'  as name,
+    'Group memberships' as label,
+    'select' as type,
+    TRUE     as multiple,
+    'press ctrl to select multiple values' as description,
+    json_arrayagg(json_object("label", name, "value", id)) as options
+from groups;
+
+insert into users(name) select :UserName where :UserName is not null;
+insert into group_members(group_id, user_id)
+select group_name, last_insert_id()
+from json_table(:Memberships, '$[*]' columns (
+    group_name int path '$'
+)) as json_elems
+where :Memberships is not null;
+
+select 'list' as component, 'Users' as title, 'No user yet' as empty_title;
+select
+    users.name as title,
+    group_concat(groups.name) as description
+from users
+left join group_members on users.id = group_members.user_id
+left join groups on groups.id = group_members.group_id
+group by users.id, users.name;