transaction_participants: name and url should be unique.

Fix #476

Author: Shkarin

src/main/resources/liquibase/version/0.4.xml

@@ -21,5 +21,6 @@
 	<include file="0.4/2016-09-28--add_creator_data_to_series_sales.xml" relativeToChangelogFile="true" />
 	<include file="0.4/2016-09-28--add_constraints_to_series-first-price.xml" relativeToChangelogFile="true" />
 	<include file="0.4/2016-10-10--change_series_sales_date_type.xml" relativeToChangelogFile="true" />
+	<include file="0.4/2016-11-29--add-unique-key-transaction_participants-table.xml" relativeToChangelogFile="true" />
 
 </databaseChangeLog>

src/main/resources/liquibase/version/0.4/2016-11-29--add-unique-key-transaction_participants-table.xml

@@ -0,0 +1,16 @@
+<?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-3.0.xsd">
+
+	<changeSet id="add-unique-key-transaction_participants-table" author="john" context="scheme">
+
+		<addUniqueConstraint
+			tableName="transaction_participants"
+			columnNames="name, url"
+			constraintName="uc_transaction_participants_name_url"/>
+	</changeSet>
+
+</databaseChangeLog>