improve the javadoc headers of the main dialects

- fix the incorrect version numbers
- add links to docs

hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java

@@ -128,7 +128,10 @@ import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithM
 import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithNanos;
 
 /**
- * A {@linkplain Dialect SQL dialect} for DB2 for LUW (Linux, Unix, and Windows) version 10.5 and above.
+ * A {@linkplain Dialect SQL dialect} for Db2 for LUW (Linux, Unix, and Windows) version 10.5 and above.
+ * <p>
+ * Please refer to the
+ * <a href="https://www.ibm.com/docs/en/db2/12.1">Db2 documentation</a>.
  *
  * @author Gavin King
  *

hibernate-core/src/main/java/org/hibernate/dialect/H2Dialect.java

@@ -109,6 +109,10 @@ import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithN
 
 /**
  * A {@linkplain Dialect SQL dialect} for H2.
+ * <p>
+ * Please refer to the
+ * <a href="http://www.h2database.com/html/main.html">H2 documentation</a>.
+ *
  *
  * @author Thomas Mueller
  * @author Jürgen Kreitler

hibernate-core/src/main/java/org/hibernate/dialect/HANADialect.java

@@ -158,13 +158,13 @@ import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithM
 
 /**
  * An SQL dialect for the SAP HANA Platform and Cloud.
- * <p>
+ * <ul>
- * For more information on SAP HANA Cloud, refer to the
+ * <li>For more information on SAP HANA Cloud, refer to the
  * <a href="https://help.sap.com/docs/hana-cloud-database/sap-hana-cloud-sap-hana-database-sql-reference-guide/sap-hana-cloud-sap-hana-database-sql-reference-guide">SAP HANA Cloud SQL Reference Guide</a>.
- * For more information on SAP HANA Platform, refer to the
+ * <li>For more information on SAP HANA Platform, refer to the
  * <a href="https://help.sap.com/docs/SAP_HANA_PLATFORM/4fe29514fd584807ac9f2a04f6754767/b4b0eec1968f41a099c828a4a6c8ca0f.html?locale=en-US">SAP HANA Platform SQL Reference Guide</a>.
- * <p>
+ * </ul>
- * Column tables are created by this dialect by default when using the auto-ddl feature.
+ * Column tables are created by this dialect by default when using the auto-DDL feature.
  *
  * @author Andrew Clemons
  * @author Jonathan Bregler

hibernate-core/src/main/java/org/hibernate/dialect/MySQLDialect.java

@@ -122,7 +122,10 @@ import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithM
 import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithMillis;
 
 /**
- * A {@linkplain Dialect SQL dialect} for MySQL 5.7 and above.
+ * A {@linkplain Dialect SQL dialect} for MySQL 8 and above.
+ * <p>
+ * Please refer to the
+ * <a href="https://dev.mysql.com/doc/refman/9.1/en/">MySQL documentation</a>.
  *
  * @author Gavin King
  */
@@ -1048,6 +1051,11 @@ public class MySQLDialect extends Dialect {
 		return '`';
 	}
 
+	/**
+	 * Here we interpret "catalog" as a MySQL database.
+	 *
+	 * @return {@code true}
+	 */
 	@Override
 	public boolean canCreateCatalog() {
 		return true;
@@ -1063,6 +1071,14 @@ public class MySQLDialect extends Dialect {
 		return new String[] { "drop database " + catalogName };
 	}
 
+	/**
+	 * MySQL does support the {@code create schema} command, but
+	 * it's a synonym for {@code create database}. Hibernate has
+	 * always treated a MySQL database as a
+	 * {@linkplain #canCreateCatalog catalog}.
+	 *
+	 * @return {@code false}
+	 */
 	@Override
 	public boolean canCreateSchema() {
 		return false;

hibernate-core/src/main/java/org/hibernate/dialect/OracleDialect.java

@@ -149,7 +149,10 @@ import static org.hibernate.type.SqlTypes.VARCHAR;
 import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithNanos;
 
 /**
- * A {@linkplain Dialect SQL dialect} for Oracle 11g Release 2 and above.
+ * A {@linkplain Dialect SQL dialect} for Oracle 19c and above.
+ * <p>
+ * Please refer to the
+ * <a href="https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/">Oracle documentation</a>.
  *
  * @author Steve Ebersole
  * @author Gavin King

hibernate-core/src/main/java/org/hibernate/dialect/PostgreSQLDialect.java

@@ -141,7 +141,10 @@ import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithM
 import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithMillis;
 
 /**
- * A {@linkplain Dialect SQL dialect} for PostgreSQL 11 and above.
+ * A {@linkplain Dialect SQL dialect} for PostgreSQL 12 and above.
+ * <p>
+ * Please refer to the
+ * <a href="https://www.postgresql.org/docs/current/index.html">PostgreSQL documentation</a>.
  *
  * @author Gavin King
  */

hibernate-core/src/main/java/org/hibernate/dialect/SQLServerDialect.java

@@ -127,7 +127,10 @@ import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithM
 import static org.hibernate.type.descriptor.DateTimeUtils.appendAsTimestampWithMillis;
 
 /**
- * A dialect for Microsoft SQL Server 2008 and above
+ * A dialect for Microsoft SQL Server 2012 and above.
+ * <p>
+ * Please refer to the
+ * <a href="https://learn.microsoft.com/en-us/sql/t-sql/language-reference">SQL Server documentation</a>.
  *
  * @author Gavin King
  */