Render windowing functions without arguments correctly.

Closes #1153
See #1019

Author: schauder

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

@@ -30,7 +30,6 @@ class SimpleFunctionVisitor extends TypedSingleConditionRenderSupport<SimpleFunc
 
 	private final StringBuilder part = new StringBuilder();
 	private boolean needsComma = false;
-	private String functionName;
 
 	SimpleFunctionVisitor(RenderContext context) {
 		super(context);
@@ -49,9 +48,6 @@ Delegation leaveNested(Visitable segment) {
 				part.append(", ");
 			}
 
-			if (part.length() == 0) {
-				part.append(functionName).append("(");
-			}
 			part.append(consumeRenderedPart());
 			needsComma = true;
 		}
@@ -66,7 +62,8 @@ Delegation leaveNested(Visitable segment) {
 	@Override
 	Delegation enterMatched(SimpleFunction segment) {
 
-		functionName = segment.getFunctionName();
+		part.append(segment.getFunctionName()).append("(");
+
 		return super.enterMatched(segment);
 	}
 

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

@@ -663,5 +663,20 @@ void renderAnalyticFunctionWithAlias() {
 			assertThat(rendered).isEqualTo(
 					"SELECT MAX(employee.salary) OVER(PARTITION BY employee.department ORDER BY employee.age) AS MAX_SELECT FROM employee");
 		}
+
+		@Test // GH-1153
+		void renderAnalyticFunctionWithOutArgument() {
+
+			final Select select = StatementBuilder.select( //
+					AnalyticFunction.create("ROW_NUMBER") //
+							.partitionBy(department)) //
+					.from(employee) //
+					.build();
+
+			String rendered = SqlRenderer.toString(select);
+
+			assertThat(rendered).isEqualTo(
+					"SELECT ROW_NUMBER() OVER(PARTITION BY employee.department) FROM employee");
+		}
 	}
 }