What's the syntax to apply hook_schema() in .install file?
The only place you use 'unsigned' is in this block:

'web_link' =&gt; array(
  'description' =&gt; 'TODO: please describe this field!',
  'type' =&gt; 'text',
  'unsigned' =&gt; TRUE,
  'not null' =&gt; TRUE,
),


'unsigned' does not apply to text columns. Try removing that line from the web_link column definition. https://api.drupal.org/api/drupal/includes!database!schema.inc/group/schemaapi/7.x has useful reference on this.

(The docs state that unsigned is ignored for other types, but it seems the error is in that chunk, so I'd certainly try removing it in case your database engine is not ignoring it.)