[#2094] Created MySQL schema version 12

The updated schema causes auto-deletion of options associated with
deleted client classes.

src/share/database/scripts/mysql/.gitignore

@@ -19,4 +19,5 @@
 /upgrade_009.5_to_009.6.sh
 /upgrade_009.6_to_010.0.sh
 /upgrade_010_to_011.sh
+/upgrade_011_to_012.sh
 /wipe_data.sh

src/share/database/scripts/mysql/dhcpdb_create.mysql

@@ -4014,6 +4014,8 @@ ALTER TABLE dhcp6_option_def
 UPDATE schema_version
     SET version = '10', minor = '0';
 
+# This line concludes database upgrade to version 10.
+
 # Reverse index order to improve reclamation query performance
 # Add a constraint that any state value added to the lease4 must
 # map to a value in the lease_state table.  Note we have to drop
@@ -4042,7 +4044,28 @@ ALTER TABLE dhcp6_client_class
 UPDATE schema_version
     SET version = '11', minor = '0';
 
-# This line concludes database upgrade to version 10.
+# This line concludes database upgrade to version 11.
+
+# Add a foreign keys referencing a client classes. If an option is
+# associated with a client class, the option will be deleted
+# along with the deleted client class.
+ALTER TABLE dhcp4_options
+    ADD CONSTRAINT fk_dhcp4_options_client_class
+        FOREIGN KEY (dhcp_client_class)
+    REFERENCES dhcp4_client_class (name)
+    ON DELETE CASCADE ON UPDATE CASCADE;
+
+ALTER TABLE dhcp6_options
+    ADD CONSTRAINT fk_dhcp6_options_client_class
+        FOREIGN KEY (dhcp_client_class)
+    REFERENCES dhcp6_client_class (name)
+    ON DELETE CASCADE ON UPDATE CASCADE;
+
+# Update the schema version number
+UPDATE schema_version
+    SET version = '12', minor = '0';
+
+# This line concludes database upgrade to version 12.
 
 # Notes:
 #

src/share/database/scripts/mysql/upgrade_011_to_012.sh.in

@@ -0,0 +1,76 @@
+#!/bin/sh
+
+# Copyright (C) 2021 Internet Systems Consortium, Inc. ("ISC")
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# shellcheck disable=SC1091
+# SC1091: Not following: ... was not specified as input (see shellcheck -x).
+
+# Exit with error if commands exit with non-zero and if undefined variables are
+# used.
+set -eu
+
+# shellcheck disable=SC2034
+# SC2034: ... appears unused. Verify use (or export if used externally).
+prefix="@prefix@"
+
+# Include utilities. Use installed version if available and
+# use build version if it isn't.
+if [ -e @datarootdir@/@PACKAGE_NAME@/scripts/admin-utils.sh ]; then
+    . "@datarootdir@/@PACKAGE_NAME@/scripts/admin-utils.sh"
+else
+    . "@abs_top_builddir@/src/bin/admin/admin-utils.sh"
+fi
+
+# Check version.
+version=$(mysql_version "${@}")
+if test "${version}" != "11.0"; then
+    printf 'This script upgrades 11.0 to 12.0. '
+    printf 'Reported version is %s. Skipping upgrade.\n' "${version}"
+    exit 0
+fi
+
+# Get the schema name from database argument. We need this to
+# query information_schema for the right database.
+for arg in "${@}"
+do
+    if ! printf '%s' "${arg}" | grep -Eq '^\-\-'
+    then
+        schema="$arg"
+        break
+    fi
+done
+
+# Make sure we have the schema.
+if [ -z "$schema" ]
+then
+    printf "Could not find database schema name in cmd line args: %s\n" "${*}"
+    exit 255
+fi
+
+mysql "$@" <<EOF
+
+-- Add a foreign keys referencing a client classes. If an option is
+-- associated with a client class, the option will be deleted
+-- along with the deleted client class.
+ALTER TABLE dhcp4_options
+    ADD CONSTRAINT fk_dhcp4_options_client_class
+        FOREIGN KEY (dhcp_client_class)
+    REFERENCES dhcp4_client_class (name)
+    ON DELETE CASCADE ON UPDATE CASCADE;
+
+ALTER TABLE dhcp6_options
+    ADD CONSTRAINT fk_dhcp6_options_client_class
+        FOREIGN KEY (dhcp_client_class)
+    REFERENCES dhcp6_client_class (name)
+    ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- Update the schema version number
+UPDATE schema_version
+    SET version = '12', minor = '0';
+
+-- This line concludes database upgrade to version 12.
+EOF