Fix order by rendering for queries containing UNION.

Make sure to append space after order by clause and fix alias detection for wrapped sub select.
Also make sure to ignore alias used in subselect so they do not conflict with root ones.

Render order by only on full select if set operator is present in EQL.

Closes #3630
Original pull request: #3429
See #3427

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/EqlQueryTransformer.java

@@ -24,6 +24,7 @@ import java.util.List;
 import org.springframework.data.domain.Sort;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
 
 /**
  * An ANTLR {@link org.antlr.v4.runtime.tree.ParseTreeVisitor} that transforms a parsed EQL query.
@@ -105,29 +106,41 @@ class EqlQueryTransformer extends EqlQueryRenderer {
 
 		if (!countQuery) {
 
-			if (ctx.orderby_clause() != null) {
+			doVisitOrderBy(tokens, ctx, ObjectUtils.isEmpty(ctx.setOperator()) ? this.sort : Sort.unsorted());
-				tokens.addAll(visit(ctx.orderby_clause()));
+
+			for (int i = 0; i < ctx.setOperator().size(); i++) {
+
+				tokens.addAll(visit(ctx.setOperator(i)));
+				tokens.addAll(visit(ctx.select_statement(i)));
 			}
 
-			if (sort.isSorted()) {
-
-				if (ctx.orderby_clause() != null) {
-
-					NOSPACE(tokens);
-					tokens.add(TOKEN_COMMA);
-				} else {
-
-					SPACE(tokens);
-					tokens.add(TOKEN_ORDER_BY);
-				}
-
-				tokens.addAll(transformerSupport.generateOrderByArguments(primaryFromAlias, sort));
-			}
 		}
 
 		return tokens;
 	}
 
+	private void doVisitOrderBy(List<JpaQueryParsingToken> tokens, EqlParser.Select_statementContext ctx, Sort sort) {
+
+		if (ctx.orderby_clause() != null) {
+			tokens.addAll(visit(ctx.orderby_clause()));
+		}
+
+		if (sort.isSorted()) {
+
+			if (ctx.orderby_clause() != null) {
+
+				NOSPACE(tokens);
+				tokens.add(TOKEN_COMMA);
+			} else {
+
+				SPACE(tokens);
+				tokens.add(TOKEN_ORDER_BY);
+			}
+
+			tokens.addAll(transformerSupport.generateOrderByArguments(primaryFromAlias, sort));
+		}
+	}
+
 	@Override
 	public List<JpaQueryParsingToken> visitSelect_clause(EqlParser.Select_clauseContext ctx) {
 

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/HqlQueryTransformer.java

@@ -26,6 +26,7 @@ import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.repository.query.HqlParser.SelectionContext;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
 
 /**
  * An ANTLR {@link org.antlr.v4.runtime.tree.ParseTreeVisitor} that transforms a parsed HQL query.
@@ -105,8 +106,7 @@ class HqlQueryTransformer extends HqlQueryRenderer {
 		}
 	}
 
-	@Override
+	private List<JpaQueryParsingToken> visitOrderedQuery(HqlParser.OrderedQueryContext ctx, Sort sort) {
-	public List<JpaQueryParsingToken> visitOrderedQuery(HqlParser.OrderedQueryContext ctx) {
 
 		List<JpaQueryParsingToken> tokens = newArrayList();
 
@@ -190,6 +190,40 @@ class HqlQueryTransformer extends HqlQueryRenderer {
 		return tokens;
 	}
 
+	@Override
+	public List<JpaQueryParsingToken> visitQueryExpression(HqlParser.QueryExpressionContext ctx) {
+
+		if (ObjectUtils.isEmpty(ctx.setOperator())) {
+			return super.visitQueryExpression(ctx);
+		}
+
+		List<JpaQueryParsingToken> builder = new ArrayList<>();
+		if (ctx.withClause() != null) {
+			builder.addAll(visit(ctx.withClause()));
+		}
+
+		List<HqlParser.OrderedQueryContext> orderedQueries = ctx.orderedQuery();
+		for (int i = 0; i < orderedQueries.size(); i++) {
+
+			if (i != 0) {
+				builder.addAll(visit(ctx.setOperator(i - 1)));
+			}
+
+			if (i == orderedQueries.size() - 1) {
+				builder.addAll(visitOrderedQuery(ctx.orderedQuery(i), this.sort));
+			} else {
+				builder.addAll(visitOrderedQuery(ctx.orderedQuery(i), Sort.unsorted()));
+			}
+		}
+
+		return builder;
+	}
+
+	@Override
+	public List<JpaQueryParsingToken> visitOrderedQuery(HqlParser.OrderedQueryContext ctx) {
+		return visitOrderedQuery(ctx, this.sort);
+	}
+
 	@Override
 	public List<JpaQueryParsingToken> visitQueryOrder(HqlParser.QueryOrderContext ctx) {
 
@@ -325,7 +359,7 @@ class HqlQueryTransformer extends HqlQueryRenderer {
 
 		List<JpaQueryParsingToken> tokens = super.visitVariable(ctx);
 
-		if (ctx.identifier() != null) {
+		if (ctx.identifier() != null && !tokens.isEmpty() && !isSubquery(ctx)) {
 			transformerSupport.registerAlias(tokens.get(tokens.size() - 1).getToken());
 		}
 
@@ -335,7 +369,7 @@ class HqlQueryTransformer extends HqlQueryRenderer {
 	@Override
 	public List<JpaQueryParsingToken> visitSelection(SelectionContext ctx) {
 
-		if(!countQuery || isSubquery(ctx)) {
+		if (!countQuery || isSubquery(ctx)) {
 			return super.visitSelection(ctx);
 		}
 

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryTransformerSupport.java

@@ -16,7 +16,7 @@ import org.springframework.util.ObjectUtils;
 
 /**
  * Transformational operations needed to support either {@link HqlQueryTransformer} or {@link JpqlQueryTransformer}.
- * 
+ *
  * @author Greg Turnquist
  * @author Donghun Shin
  * @since 3.1
@@ -47,12 +47,12 @@ class JpaQueryTransformerSupport {
 	/**
 	 * Using the primary {@literal FROM} clause's alias and a {@link Sort}, construct all the {@literal ORDER BY}
 	 * arguments.
-	 * 
+	 *
 	 * @param primaryFromAlias
 	 * @param sort
 	 * @return
 	 */
-	List<JpaQueryParsingToken> generateOrderByArguments(String primaryFromAlias, Sort sort) {
+	List<JpaQueryParsingToken> generateOrderByArguments(@Nullable String primaryFromAlias, Sort sort) {
 
 		List<JpaQueryParsingToken> tokens = new ArrayList<>();
 
@@ -98,7 +98,7 @@ class JpaQueryTransformerSupport {
 	/**
 	 * Using the {@code primaryFromAlias} and the {@link org.springframework.data.domain.Sort.Order}, construct a suitable
 	 * argument to be added to an {@literal ORDER BY} expression.
-	 * 
+	 *
 	 * @param primaryFromAlias
 	 * @param order
 	 * @return

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/EqlQueryTransformerTests.java

@@ -753,6 +753,15 @@ class EqlQueryTransformerTests {
 				""");
 	}
 
+	@Test // GH-3427
+	void sortShouldBeAppendedToFullSelectOnlyInCaseOfSetOperator() {
+
+		String source = "SELECT tb FROM Test tb WHERE (tb.type='A') UNION SELECT tb FROM Test tb WHERE (tb.type='B')";
+		String target = createQueryFor(source, Sort.by("Type").ascending());
+
+		assertThat(target).isEqualTo("SELECT tb FROM Test tb WHERE (tb.type = 'A') UNION SELECT tb FROM Test tb WHERE (tb.type = 'B') order by tb.Type asc");
+	}
+
 	static Stream<Arguments> queriesWithReservedWordsAsIdentifiers() {
 
 		return Stream.of( //

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/HqlQueryTransformerTests.java

@@ -17,6 +17,8 @@ package org.springframework.data.jpa.repository.query;
 
 import static org.assertj.core.api.Assertions.*;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
 import org.assertj.core.api.SoftAssertions;
@@ -24,11 +26,13 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.domain.JpaSort;
 import org.springframework.lang.Nullable;
+import org.springframework.util.StringUtils;
 
 /**
  * Verify that HQL queries are properly transformed through the {@link JpaQueryEnhancer} and the {@link HqlQueryParser}.
@@ -1060,6 +1064,40 @@ class HqlQueryTransformerTests {
 		assertCountQuery("select distinct a, count(b) as c from Employee GROUP BY n","select count(distinct a, count(b)) from Employee AS __ GROUP BY n");
 	}
 
+	@Test // GH-3427
+	void sortShouldBeAppendedWithSpacingInCaseOfSetOperator() {
+
+        String source = "SELECT tb FROM Test tb WHERE (tb.type='A') UNION SELECT tb FROM Test tb WHERE (tb.type='B')";
+		String target = createQueryFor(source, Sort.by("Type").ascending());
+		
+		assertThat(target).isEqualTo("SELECT tb FROM Test tb WHERE (tb.type = 'A') UNION SELECT tb FROM Test tb WHERE (tb.type = 'B') order by tb.Type asc");
+	}
+
+	@ParameterizedTest // GH-3427
+	@ValueSource(strings = {"", "res"})
+	void sortShouldBeAppendedToSubSelectWithSetOperatorInSubselect(String alias) {
+
+		String prefix = StringUtils.hasText(alias) ? (alias + ".") : "";
+		String source = "SELECT %sname FROM (SELECT c.name as name FROM Category c UNION SELECT t.name as name FROM Tag t)".formatted(prefix);
+		if(StringUtils.hasText(alias)) {
+			source = source + " %s".formatted(alias);
+		}
+
+		String target = createQueryFor(source, Sort.by("name").ascending());
+
+		assertThat(target).contains(" UNION SELECT ").doesNotContainPattern(Pattern.compile(".*\\SUNION"));
+		assertThat(target).endsWith("order by %sname asc".formatted(prefix)).satisfies(it -> {
+			Pattern pattern = Pattern.compile("order by %sname".formatted(prefix));
+			Matcher matcher = pattern.matcher(target);
+			int count = 0;
+			while(matcher.find()) {
+				count++;
+			}
+			assertThat(count).describedAs("Found order by clause more than once in: \n%s", it).isOne();
+		});
+
+	}
+
 	private void assertCountQuery(String originalQuery, String countQuery) {
 		assertThat(createCountQueryFor(originalQuery)).isEqualTo(countQuery);
 	}