Add support for full outer join to SelectBuilder.

Original pull request #1421

Author: schauder

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/DefaultSelectBuilder.java

@@ -181,6 +181,11 @@ public SelectOn leftOuterJoin(TableLike table) {
 		return new JoinBuilder(table, this, JoinType.LEFT_OUTER_JOIN);
 	}
 
+	@Override
+	public SelectOn fullOuterJoin(TableLike table) {
+		return new JoinBuilder(table, this, JoinType.FULL_OUTER_JOIN);
+	}
+
 	public DefaultSelectBuilder join(Join join) {
 		this.joins.add(join);
 
@@ -323,6 +328,12 @@ public SelectOn leftOuterJoin(TableLike table) {
 			return selectBuilder.leftOuterJoin(table);
 		}
 
+		@Override
+		public SelectOn fullOuterJoin(TableLike table) {
+			selectBuilder.join(finishJoin());
+			return selectBuilder.fullOuterJoin(table);
+		}
+
 		@Override
 		public SelectFromAndJoin limitOffset(long limit, long offset) {
 			selectBuilder.join(finishJoin());

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/SelectBuilder.java

@@ -486,6 +486,16 @@ interface SelectJoin extends SelectLock, BuildSelect {
 		 * @see SQL#table(String)
 		 */
 		SelectOn leftOuterJoin(TableLike table);
+
+		/**
+		 * Declare a {@code FULL OUTER JOIN} {@link Table}.
+		 *
+		 * @param table must not be {@literal null}.
+		 * @return {@code this} builder.
+		 * @see Join
+		 * @see SQL#table(String)
+		 */
+		SelectOn fullOuterJoin(TableLike table);
 	}
 
 	/**

spring-data-relational/src/test/java/org/springframework/data/relational/core/sql/render/SelectRendererUnitTests.java

@@ -154,6 +154,21 @@ void shouldRenderOuterJoin() {
 				+ "LEFT OUTER JOIN department ON employee.department_id = department.id");
 	}
 
+	@Test // GH-1421
+	void shouldRenderFullOuterJoin() {
+
+		Table employee = SQL.table("employee");
+		Table department = SQL.table("department");
+
+		Select select = Select.builder().select(employee.column("id"), department.column("name")) //
+				.from(employee) //
+				.fullOuterJoin(department).on(employee.column("department_id")).equals(department.column("id")) //
+				.build();
+
+		assertThat(SqlRenderer.toString(select)).isEqualTo("SELECT employee.id, department.name FROM employee "
+				+ "FULL OUTER JOIN department ON employee.department_id = department.id");
+	}
+
 	@Test // DATAJDBC-309
 	void shouldRenderSimpleJoinWithAnd() {