HHH-16619 don't generate table aliases beginning with _

- because Oracle hates that
- also, as suggested by @sebersole common in code, start
  generating "acronym"-based aliases

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/SqlAliasStemHelper.java

@@ -11,6 +11,7 @@ import org.hibernate.internal.util.StringHelper;
 
 /**
  * @author Steve Ebersole
+ * @author Gavin King
  */
 public class SqlAliasStemHelper {
 	/**
@@ -19,13 +20,7 @@ public class SqlAliasStemHelper {
 	public static final SqlAliasStemHelper INSTANCE = new SqlAliasStemHelper();
 
 	public String generateStemFromEntityName(String entityName) {
-		final String simpleName = toSimpleEntityName( entityName );
+		return acronym( toSimpleEntityName( entityName ) );
-
-		// ideally I'd like to build the alias base from acronym form of the name.  E.g.
-		// 'TransportationMethod` becomes 'tm', 'ShippingDestination` becomes 'sd', etc
-
-		// for now, just use the first letter
-		return Character.toString( Character.toLowerCase( simpleName.charAt( 0 ) ) );
 	}
 
 	private String toSimpleEntityName(String entityName) {
@@ -41,7 +36,23 @@ public class SqlAliasStemHelper {
 	}
 
 	public String generateStemFromAttributeName(String attributeName) {
-		// see note above, again for now just use the first letter
+		return acronym(attributeName);
-		return Character.toString( Character.toLowerCase( attributeName.charAt( 0 ) ) );
+	}
+
+
+	private String acronym(String name) {
+		StringBuilder string = new StringBuilder();
+		char last = '\0';
+		for (int i = 0; i<name.length(); i++ ) {
+			char ch = name.charAt(i);
+			if ( Character.isLetter(ch) ) {
+				if ( string.length() == 0
+						|| Character.isUpperCase(ch) && !Character.isUpperCase(last) ) {
+					string.append( Character.toLowerCase(ch) );
+				}
+			}
+			last = ch;
+		}
+		return string.length() == 0 ? "z" : string.toString();
 	}
 }

hibernate-core/src/test/java/org/hibernate/orm/test/associations/FieldWithUnderscoreTest.java

@@ -0,0 +1,31 @@
+package org.hibernate.orm.test.associations;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.Test;
+
+@SessionFactory
+@DomainModel(annotatedClasses = {FieldWithUnderscoreTest.A.class, FieldWithUnderscoreTest.B.class})
+public class FieldWithUnderscoreTest {
+
+    @Test void test(SessionFactoryScope scope) {
+        scope.inSession(s -> s.createSelectionQuery("from B join _a").getResultList());
+        scope.inSession(s -> s.createSelectionQuery("from B left join fetch _a").getResultList());
+    }
+
+    @Entity(name = "A")
+    static class A {
+        @Id Long _id;
+
+    }
+    @Entity(name = "B")
+    static class B {
+        @Id Long _id;
+        @ManyToOne(fetch = FetchType.LAZY) A _a;
+    }
+}

hibernate-core/src/test/java/org/hibernate/orm/test/graph/HHH15065Test.java

@@ -46,11 +46,11 @@ class HHH15065Test {
 		SQLStatementInspector statementInspector = scope.getCollectingStatementInspector();
 		List<String> sqlQueries = statementInspector.getSqlQueries();
 		assertEquals( 1, sqlQueries.size() );
-		assertEquals( "select b1_0.id,a1_0.id,a1_0.name,c1_0.id,c1_0.name,c2_0.id,c2_0.name,e1_0.id,e1_0.name" +
+		assertEquals( "select b1_0.id,a1_0.id,a1_0.name,ca1_0.id,ca1_0.name,ce1_0.id,ce1_0.name,e1_0.id,e1_0.name" +
 					 " from Book b1_0" +
 					 " left join Person a1_0 on a1_0.id=b1_0.author_id" +
-					 " left join Person c1_0 on c1_0.id=b1_0.coAuthor_id" +
+					 " left join Person ca1_0 on ca1_0.id=b1_0.coAuthor_id" +
-					 " left join Person c2_0 on c2_0.id=b1_0.coEditor_id" +
+					 " left join Person ce1_0 on ce1_0.id=b1_0.coEditor_id" +
 					 " left join Person e1_0 on e1_0.id=b1_0.editor_id", sqlQueries.get(0) );
 	}
 

hibernate-core/src/test/java/org/hibernate/orm/test/hql/ManyToOneJoinReuseTest.java

@@ -56,7 +56,7 @@ public class ManyToOneJoinReuseTest {
 					session.createQuery( query ).getResultList();
 					assertEquals( 1, sqlStatementInterceptor.getSqlQueries().size() );
 					assertEquals(
-							"select b1_0.id,b2_0.isbn,b2_0.title from BookList b1_0 join book b2_0 on b2_0.isbn=b1_0.book_isbn where b2_0.isbn is not null",
+							"select bl1_0.id,b1_0.isbn,b1_0.title from BookList bl1_0 join book b1_0 on b1_0.isbn=bl1_0.book_isbn where b1_0.isbn is not null",
 							sqlStatementInterceptor.getSqlQueries().get( 0 )
 					);
 				}
@@ -85,7 +85,7 @@ public class ManyToOneJoinReuseTest {
 					session.createQuery( query ).getResultList();
 					assertEquals( 1, sqlStatementInterceptor.getSqlQueries().size() );
 					assertEquals(
-							"select b1_0.id,b1_0.book_isbn from BookList b1_0 join book b2_0 on b2_0.isbn=b1_0.book_isbn where b2_0.isbn is not null and b1_0.book_isbn is not null",
+							"select bl1_0.id,bl1_0.book_isbn from BookList bl1_0 join book b1_0 on b1_0.isbn=bl1_0.book_isbn where b1_0.isbn is not null and bl1_0.book_isbn is not null",
 							sqlStatementInterceptor.getSqlQueries().get( 0 )
 					);
 				}

hibernate-core/src/test/java/org/hibernate/orm/test/inheritance/InheritanceQueryGroupByTest.java

@@ -105,11 +105,7 @@ public class InheritanceQueryGroupByTest {
 		statementInspector.clear();
 		scope.inTransaction( session -> {
 			final MyPojo myPojo = session.createQuery(
-					String.format(
+					"select new MyPojo(sum(e.amount), re) from MyEntity e join e." + parentProp + " re group by re",
-							"select new %s(sum(e.amount), re) from MyEntity e join e.%s re group by re",
-							MyPojo.class.getName(),
-							parentProp
-					),
 					MyPojo.class
 			).getSingleResult();
 			assertThat( myPojo.getAmount() ).isEqualTo( 3L );

hibernate-core/src/test/java/org/hibernate/orm/test/jpa/criteria/TreatDisjunctionTest.java

@@ -78,13 +78,13 @@ public class TreatDisjunctionTest {
 					sqlStatementInterceptor.assertExecutedCount( 1 );
 					assertEquals(
 							"select " +
-									"p1_0.id," +
+									"pd1_0.id," +
-									"p1_0.DTYPE," +
+									"pd1_0.DTYPE," +
-									"p1_0.active," +
+									"pd1_0.active," +
-									"p1_0.openldap " +
+									"pd1_0.openldap " +
-									"from PAccountDirectory p1_0 " +
+									"from PAccountDirectory pd1_0 " +
-									"where p1_0.active=? " +
+									"where pd1_0.active=? " +
-									"or p1_0.openldap=?",
+									"or pd1_0.openldap=?",
 							sqlStatementInterceptor.getSqlQueries().get( 0 )
 					);
 				}

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/fetch/depth/DepthOneBatchTest.java

@@ -92,7 +92,7 @@ public class DepthOneBatchTest {
 							"select a1_0.agency_id,a1_0.agency_txt from agency_table a1_0 where a1_0.agency_id=?"
 					);
 					assertThat( executedQueries.get( 1 ).toLowerCase() ).isEqualTo(
-							"select a1_0.agency_id,a1_0.agency_detail from agency_detail_table a1_0 where a1_0.agency_id=?"
+							"select ad1_0.agency_id,ad1_0.agency_detail from agency_detail_table ad1_0 where ad1_0.agency_id=?"
 					);
 
 					assertThat( executedQueries.get( 2 ).toLowerCase() ).isEqualTo(

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/fetch/depth/DepthOneTest.java

@@ -88,7 +88,7 @@ public class DepthOneTest {
 					assertThat( executedQueries.size() ).isEqualTo( 5 );
 
 					assertThat( executedQueries.get( 0 ).toLowerCase() ).isEqualTo(
-							"select a1_0.agency_id,a2_0.agency_id,a2_0.agency_detail,a1_0.agency_txt from agency_table a1_0 left join agency_detail_table a2_0 on a2_0.agency_id=a1_0.agency_id where a1_0.agency_id=?"
+							"select a1_0.agency_id,ad1_0.agency_id,ad1_0.agency_detail,a1_0.agency_txt from agency_table a1_0 left join agency_detail_table ad1_0 on ad1_0.agency_id=a1_0.agency_id where a1_0.agency_id=?"
 					);
 
 					assertThat( executedQueries.get( 1 ).toLowerCase() ).isEqualTo(
@@ -104,7 +104,7 @@ public class DepthOneTest {
 					);
 
 					assertThat( executedQueries.get( 4 ).toLowerCase() ).isEqualTo(
-							"select a1_0.agency_id,a1_0.agency_detail from agency_detail_table a1_0 where a1_0.agency_id=?"
+							"select ad1_0.agency_id,ad1_0.agency_detail from agency_detail_table ad1_0 where ad1_0.agency_id=?"
 					);
 				}
 		);

hibernate-core/src/test/java/org/hibernate/orm/test/query/CompareEntityValuedPathsTest.java

@@ -42,9 +42,9 @@ public class CompareEntityValuedPathsTest {
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
 									"where p1_0.uk in (" +
-									"select c1_0.child_uk " +
+									"select cu1_0.child_uk " +
-									"from children_uks c1_0 " +
+									"from children_uks cu1_0 " +
-									"where p1_0.uk=c1_0.owner_uk" +
+									"where p1_0.uk=cu1_0.owner_uk" +
 									")",
 							statementInspector.getSqlQueries().get( 0 )
 					);
@@ -110,10 +110,10 @@ public class CompareEntityValuedPathsTest {
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
 									"where p1_0.parent_id in (" +
-									"select c1_1.id " +
+									"select cu1_1.id " +
-									"from children_uks c1_0 " +
+									"from children_uks cu1_0 " +
-									"join PERSON_TABLE c1_1 on c1_1.uk=c1_0.child_uk " +
+									"join PERSON_TABLE cu1_1 on cu1_1.uk=cu1_0.child_uk " +
-									"where p1_0.uk=c1_0.owner_uk" +
+									"where p1_0.uk=cu1_0.owner_uk" +
 									")",
 							statementInspector.getSqlQueries().get( 0 )
 					);
@@ -134,8 +134,8 @@ public class CompareEntityValuedPathsTest {
 							"select " +
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
-									"join PERSON_TABLE p2_0 on p2_0.uk=p1_0.parent_uk " +
+									"join PERSON_TABLE pu1_0 on pu1_0.uk=p1_0.parent_uk " +
-									"where p2_0.id in (" +
+									"where pu1_0.id in (" +
 									"select c1_0.children_id " +
 									"from PERSON_TABLE_PERSON_TABLE c1_0 " +
 									"where p1_0.id=c1_0.Person_id" +
@@ -184,9 +184,9 @@ public class CompareEntityValuedPathsTest {
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
 									"where p1_0.id in (" +
-									"select e1_0.id " +
+									"select eu1_0.id " +
-									"from PERSON_TABLE e1_0 " +
+									"from PERSON_TABLE eu1_0 " +
-									"where p1_0.uk=e1_0.supervisor_uk" +
+									"where p1_0.uk=eu1_0.supervisor_uk" +
 									")",
 							statementInspector.getSqlQueries().get( 0 )
 					);
@@ -207,8 +207,8 @@ public class CompareEntityValuedPathsTest {
 							"select " +
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
-									"join children_uks c1_0 on p1_0.uk=c1_0.owner_uk " +
+									"join children_uks cu1_0 on p1_0.uk=cu1_0.owner_uk " +
-									"where c1_0.child_uk is not null",
+									"where cu1_0.child_uk is not null",
 							statementInspector.getSqlQueries().get( 0 )
 					);
 				}
@@ -249,9 +249,9 @@ public class CompareEntityValuedPathsTest {
 							"select " +
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
-									"join (children_uks c1_0 join PERSON_TABLE c1_1 on c1_1.uk=c1_0.child_uk) on p1_0.uk=c1_0.owner_uk " +
+									"join (children_uks cu1_0 join PERSON_TABLE cu1_1 on cu1_1.uk=cu1_0.child_uk) on p1_0.uk=cu1_0.owner_uk " +
-									"join PERSON_TABLE_PERSON_TABLE c2_0 on p1_0.id=c2_0.Person_id " +
+									"join PERSON_TABLE_PERSON_TABLE c1_0 on p1_0.id=c1_0.Person_id " +
-									"where c1_1.id=c2_0.children_id",
+									"where cu1_1.id=c1_0.children_id",
 							statementInspector.getSqlQueries().get( 0 )
 					);
 				}
@@ -272,8 +272,8 @@ public class CompareEntityValuedPathsTest {
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
 									"join PERSON_TABLE_PERSON_TABLE c1_0 on p1_0.id=c1_0.Person_id " +
-									"join (children_uks c2_0 join PERSON_TABLE c2_1 on c2_1.uk=c2_0.child_uk) on p1_0.uk=c2_0.owner_uk " +
+									"join (children_uks cu1_0 join PERSON_TABLE cu1_1 on cu1_1.uk=cu1_0.child_uk) on p1_0.uk=cu1_0.owner_uk " +
-									"where c1_0.children_id=c2_1.id",
+									"where c1_0.children_id=cu1_1.id",
 							statementInspector.getSqlQueries().get( 0 )
 					);
 				}
@@ -293,8 +293,8 @@ public class CompareEntityValuedPathsTest {
 							"select " +
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
-									"join (children_uks c1_0 join PERSON_TABLE c1_1 on c1_1.uk=c1_0.child_uk) on p1_0.uk=c1_0.owner_uk " +
+									"join (children_uks cu1_0 join PERSON_TABLE cu1_1 on cu1_1.uk=cu1_0.child_uk) on p1_0.uk=cu1_0.owner_uk " +
-									"where c1_1.id in (select c2_0.children_id from PERSON_TABLE_PERSON_TABLE c2_0 where p1_0.id=c2_0.Person_id)",
+									"where cu1_1.id in (select c1_0.children_id from PERSON_TABLE_PERSON_TABLE c1_0 where p1_0.id=c1_0.Person_id)",
 							statementInspector.getSqlQueries().get( 0 )
 					);
 				}
@@ -315,7 +315,7 @@ public class CompareEntityValuedPathsTest {
 									"1 " +
 									"from PERSON_TABLE p1_0 " +
 									"join PERSON_TABLE_PERSON_TABLE c1_0 on p1_0.id=c1_0.Person_id " +
-									"where c1_0.children_id in (select c2_1.id from children_uks c2_0 join PERSON_TABLE c2_1 on c2_1.uk=c2_0.child_uk where p1_0.uk=c2_0.owner_uk)",
+									"where c1_0.children_id in (select cu1_1.id from children_uks cu1_0 join PERSON_TABLE cu1_1 on cu1_1.uk=cu1_0.child_uk where p1_0.uk=cu1_0.owner_uk)",
 							statementInspector.getSqlQueries().get( 0 )
 					);
 				}

hibernate-core/src/test/java/org/hibernate/orm/test/query/QueryTimeOutTest.java

@@ -68,7 +68,7 @@ public class QueryTimeOutTest extends BaseNonConfigCoreFunctionalTestCase {
 		);
 		final String baseQuery;
 		if ( DialectContext.getDialect() instanceof OracleDialect ) {
-			baseQuery = "update AnEntity a1_0 set a1_0.name=";
+			baseQuery = "update AnEntity ae1_0 set ae1_0.name=";
 		}
 		else {
 			baseQuery = "update AnEntity set name=";

hibernate-core/src/test/java/org/hibernate/orm/test/query/hql/SameTableAliasInSubqueryWithEmbeddedTest.java

@@ -99,8 +99,8 @@ public class SameTableAliasInSubqueryWithEmbeddedTest {
 			query.setParameter( "countryCode", "DE" );
 			query.setParameter( "nested", "NESTED_2" );
 			assertNotNull( query.getSingleResult() );
-			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "m1_0", 6 );
+			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "mdfe1_0", 6 );
-			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "m2_0", 5 );
+			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "mdfe2_0", 5 );
 		} );
 	}
 
@@ -118,8 +118,8 @@ public class SameTableAliasInSubqueryWithEmbeddedTest {
 			TypedQuery<PrimaryKey> query = session.createQuery( jpql, PrimaryKey.class );
 			query.setParameter( "nested", "NESTED_2" );
 			assertNotNull( query.getSingleResult() );
-			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "m1_0", 4 );
+			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "mdfe1_0", 4 );
-			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "m2_0", 3 );
+			statementInspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "mdfe2_0", 3 );
 		} );
 	}
 

hibernate-core/src/test/java/org/hibernate/orm/test/sql/ast/SmokeTests.java

@@ -81,9 +81,9 @@ public class SmokeTests {
 			assertThat( rootTableGroup.getTableGroupJoins().isEmpty(), is( true ) );
 
 
-			// `s` is the "alias stem" for `SimpleEntity` and as it is the first entity with that stem in
+			// `se` is the "alias stem" for `SimpleEntity` and as it is the first entity with that stem in
-			// the query the base becomes `s1`.  The primary table reference is always suffixed as `_0`
+			// the query the base becomes `se1`.  The primary table reference is always suffixed as `_0`
-			assertThat( rootTableGroup.getPrimaryTableReference().getIdentificationVariable(), is( "s1_0" ) );
+			assertThat( rootTableGroup.getPrimaryTableReference().getIdentificationVariable(), is( "se1_0" ) );
 
 			final SelectClause selectClause = sqlAst.getQuerySpec().getSelectClause();
 			assertThat( selectClause.getSqlSelections().size(), is( 1 ) ) ;
@@ -99,7 +99,7 @@ public class SmokeTests {
 
 			assertThat(
 					jdbcSelectOperation.getSqlString(),
-					is( "select s1_0.name from mapping_simple_entity s1_0" )
+					is( "select se1_0.name from mapping_simple_entity se1_0" )
 			);
 		} );
 	}
@@ -137,9 +137,9 @@ public class SmokeTests {
 					assertThat( rootTableGroup.getTableGroupJoins().isEmpty(), is( true ) );
 
 
-					// `s` is the "alias stem" for `SimpleEntity` and as it is the first entity with that stem in
+					// `se` is the "alias stem" for `SimpleEntity` and as it is the first entity with that stem in
-					// the query the base becomes `s1`.  The primary table reference is always suffixed as `_0`
+					// the query the base becomes `se1`.  The primary table reference is always suffixed as `_0`
-					assertThat( rootTableGroup.getPrimaryTableReference().getIdentificationVariable(), is( "s1_0" ) );
+					assertThat( rootTableGroup.getPrimaryTableReference().getIdentificationVariable(), is( "se1_0" ) );
 
 					final SelectClause selectClause = sqlAst.getQuerySpec().getSelectClause();
 					assertThat( selectClause.getSqlSelections().size(), is( 1 ) );
@@ -153,7 +153,7 @@ public class SmokeTests {
 					final Expression selectedExpression = sqlSelection.getExpression();
 					assertThat( selectedExpression, instanceOf( ColumnReference.class ) );
 					final ColumnReference columnReference = (ColumnReference) selectedExpression;
-					assertThat( columnReference.getExpressionText(), is( "s1_0.gender" ) );
+					assertThat( columnReference.getExpressionText(), is( "se1_0.gender" ) );
 
 					final JdbcMapping selectedExpressible = selectedExpression.getExpressionType().getSingleJdbcMapping();
 					assertThat( selectedExpressible.getJdbcType().isInteger(), is( true ) );
@@ -184,7 +184,7 @@ public class SmokeTests {
 
 					assertThat(
 							jdbcSelectOperation.getSqlString(),
-							is( "select s1_0.gender from mapping_simple_entity s1_0" )
+							is( "select se1_0.gender from mapping_simple_entity se1_0" )
 					);
 				}
 		);