moodle-local-corfows/db/install.xml

<?xml version="1.0" encoding="UTF-8" ?>
<XMLDB PATH="local/corfows/db" VERSION="20201124" COMMENT="XMLDB file for Moodle local/corfows"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="../../../lib/xmldb/xmldb.xsd"
>
  <TABLES>
    <TABLE NAME="local_corfows_validation" COMMENT="CORFO validation of custom cert issues.">
      <FIELDS>
        <FIELD NAME="id" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="true"/>
        <FIELD NAME="issue_id" TYPE="int" LENGTH="10" NOTNULL="true" DEFAULT="0" SEQUENCE="false" COMMENT="customcert_issues id"/>
      </FIELDS>
      <KEYS>
        <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
        <KEY NAME="issue" TYPE="foreign-unique" FIELDS="issue_id" REFTABLE="customcert_issues" REFFIELDS="id"/>
      </KEYS>
    </TABLE>
  </TABLES>
</XMLDB>