also use enum type for boolean->char mappings on MySQL

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

@@ -653,6 +653,10 @@ public abstract class Dialect implements ConversionContext {
 		}
 	}
 
+	public String getBooleanTypeDeclaration(int sqlType, char falseChar, char trueChar) {
+		return null;
+	}
+
 	/**
 	 * Render a SQL check condition for a column that represents a boolean value.
 	 */

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

@@ -771,12 +771,23 @@ public class MySQLDialect extends Dialect {
 		}
 	}
 
+	@Override
+	public String getBooleanTypeDeclaration(int sqlType, char falseChar, char trueChar) {
+		return isCharacterType( sqlType ) ? "enum ('" + falseChar + "','" + trueChar + "')" : null;
+	}
+
 	@Override
 	public String getEnumCheckCondition(String columnName, int sqlType, Class<? extends Enum<?>> enumClass) {
 		// don't need it, since we're using the 'enum' type
 		return null;
 	}
 
+	@Override
+	public String getBooleanCheckCondition(String columnName, int sqlType, char falseChar, char trueChar) {
+		return isCharacterType( sqlType ) ? null
+				: super.getBooleanCheckCondition( columnName, sqlType, falseChar, trueChar );
+	}
+
 	@Override
 	public String getQueryHintString(String query, String hints) {
 		return IndexQueryHintHandler.INSTANCE.addQueryHints( query, hints );

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/BooleanJavaType.java

@@ -168,13 +168,21 @@ public class BooleanJavaType extends AbstractClassJavaType<Boolean> implements
 	}
 
 	@Override
-	public String getCheckCondition(String columnName, JdbcType sqlTypeDescriptor, Dialect dialect) {
+	public String getCheckCondition(String columnName, JdbcType jdbcType, Dialect dialect) {
 		return dialect.getBooleanCheckCondition(
 				columnName,
-				sqlTypeDescriptor.getJdbcTypeCode(),
+				jdbcType.getJdbcTypeCode(),
 				characterValueFalse,
 				characterValueTrue
 		);
 	}
 
+	@Override
+	public String getSpecializedTypeDeclaration(JdbcType jdbcType, Dialect dialect) {
+		return dialect.getBooleanTypeDeclaration(
+				jdbcType.getJdbcTypeCode(),
+				characterValueFalse,
+				characterValueTrue
+		);
+	}
 }