task: mark series.perforated field as nullable

Part of #1550

Author: php-coder

src/main/resources/liquibase/version/0.4.7.xml

@@ -6,5 +6,6 @@
 		http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.9.xsd">
 
 	<include file="0.4.7/2021-07-18--series_import_parsed_image_urls.xml" relativeToChangelogFile="true" />
+	<include file="0.4.7/2021-11-28--series_and_nullable_perforated_field.xml" relativeToChangelogFile="true" />
 
 </databaseChangeLog>

src/main/resources/liquibase/version/0.4.7/2021-11-28--series_and_nullable_perforated_field.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<databaseChangeLog
+		xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
+		http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.3.xsd">
+	
+	<changeSet id="make-series-perforated-field-nullable" author="php-coder" context="scheme">
+		
+		<dropNotNullConstraint
+			tableName="series"
+			columnName="perforated"
+			columnDataType="BOOLEAN"
+		/>
+		
+		<setColumnRemarks
+			tableName="series"
+			columnName="perforated"
+			columnDataType="BOOLEAN"
+			remarks="NULL means a series contains both types of stamps: perforated and imperforated"
+		/>
+		
+	</changeSet>
+	
+</databaseChangeLog>