HHH-18463 Add AzureDialect and determine SQL Server version based on compatibility level

Author: beikov

hibernate-core/src/main/java/org/hibernate/cfg/DialectSpecificSettings.java

@@ -67,6 +67,12 @@ public interface DialectSpecificSettings {
 	 */
 	public static final String COCKROACH_VERSION_STRING = "hibernate.dialect.cockroach.version_string";
 
+	/**
+	 * Specifies the compatibility level of the SQL Server database as returned by {@code select compatibility_level from sys.databases}.
+	 * The number has three digits, the first two digits are the major version, the last digit is the minor version.
+	 */
+	public static final String SQL_SERVER_COMPATIBILITY_LEVEL = "hibernate.dialect.sqlserver.compatibility_level";
+
 	/**
 	 * Specifies the LOB prefetch size. LOBs larger than this value will be read into memory as the HANA JDBC driver closes
 	 * the LOB when the result set is closed.

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

@@ -0,0 +1,25 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.dialect;
+
+import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
+
+/**
+ * A {@linkplain Dialect SQL dialect} for Azure SQL Server.
+ */
+public class AzureSQLServerDialect extends SQLServerDialect {
+
+	public AzureSQLServerDialect() {
+		// Azure SQL Server always is the latest version, so default to a high number
+		super( DatabaseVersion.make( Integer.MAX_VALUE ) );
+	}
+
+	public AzureSQLServerDialect(DialectResolutionInfo info) {
+		this();
+		registerKeywords( info );
+	}
+}

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

@@ -7,6 +7,7 @@
 package org.hibernate.dialect;
 
 import java.sql.DatabaseMetaData;
+import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Types;
 import java.time.temporal.ChronoField;
@@ -40,6 +41,7 @@
 import org.hibernate.dialect.unique.AlterTableUniqueIndexDelegate;
 import org.hibernate.dialect.unique.UniqueDelegate;
 import org.hibernate.engine.jdbc.Size;
+import org.hibernate.engine.jdbc.dialect.spi.BasicSQLExceptionConverter;
 import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
 import org.hibernate.engine.jdbc.env.spi.IdentifierCaseStrategy;
 import org.hibernate.engine.jdbc.env.spi.IdentifierHelper;
@@ -52,6 +54,7 @@
 import org.hibernate.exception.spi.TemplatedViolatedConstraintNameExtractor;
 import org.hibernate.exception.spi.ViolatedConstraintNameExtractor;
 import org.hibernate.internal.util.JdbcExceptionHelper;
+import org.hibernate.internal.util.config.ConfigurationHelper;
 import org.hibernate.mapping.Column;
 import org.hibernate.persister.entity.mutation.EntityMutationTarget;
 import org.hibernate.procedure.internal.SQLServerCallableStatementSupport;
@@ -89,6 +92,7 @@
 
 import jakarta.persistence.TemporalType;
 
+import static org.hibernate.cfg.DialectSpecificSettings.SQL_SERVER_COMPATIBILITY_LEVEL;
 import static org.hibernate.exception.spi.TemplatedViolatedConstraintNameExtractor.extractUsingTemplate;
 import static org.hibernate.query.sqm.TemporalUnit.NANOSECOND;
 import static org.hibernate.query.sqm.produce.function.FunctionParameterType.INTEGER;
@@ -174,8 +178,36 @@ public SQLServerDialect(DatabaseVersion version) {
 	}
 
 	public SQLServerDialect(DialectResolutionInfo info) {
-		super(info);
-		exporter = createSequenceExporter(info);
+		this( determineDatabaseVersion( info ) );
+		registerKeywords( info );
+	}
+
+	private static DatabaseVersion determineDatabaseVersion(DialectResolutionInfo info) {
+		final Integer compatibilityLevel = getCompatibilityLevel( info );
+		if ( compatibilityLevel != null ) {
+			final int majorVersion = compatibilityLevel / 10;
+			final int minorVersion = compatibilityLevel % 10;
+			return DatabaseVersion.make( majorVersion, minorVersion );
+		}
+		return info.makeCopyOrDefault( MINIMUM_VERSION );
+	}
+
+	private static Integer getCompatibilityLevel(DialectResolutionInfo info) {
+		final DatabaseMetaData databaseMetaData = info.getDatabaseMetadata();
+		if ( databaseMetaData != null ) {
+			try ( java.sql.Statement statement = databaseMetaData.getConnection().createStatement() ) {
+				final ResultSet rs = statement.executeQuery( "SELECT compatibility_level FROM sys.databases where name = db_name();" );
+				if ( rs.next() ) {
+					return rs.getInt( 1 );
+				}
+			}
+			catch (SQLException e) {
+				throw BasicSQLExceptionConverter.INSTANCE.convert( e );
+			}
+		}
+
+		// default to the dialect-specific configuration setting
+		return ConfigurationHelper.getInteger( SQL_SERVER_COMPATIBILITY_LEVEL, info.getConfigurationValues() );
 	}
 
 	private StandardSequenceExporter createSequenceExporter(DatabaseVersion version) {