Do not return null as name of the catalog/schema/table from SimpleResultSet

h2/src/main/org/h2/tools/SimpleResultSet.java

@@ -1984,14 +1984,14 @@ public class SimpleResultSet implements ResultSet, ResultSetMetaData,
     }
 
     /**
-     * Returns null.
+     * Returns empty string.
      *
      * @param columnIndex (1,2,...)
-     * @return null
+     * @return empty string
      */
     @Override
     public String getCatalogName(int columnIndex) {
-        return null;
+        return "";
     }
 
     /**
@@ -2040,25 +2040,25 @@ public class SimpleResultSet implements ResultSet, ResultSetMetaData,
     }
 
     /**
-     * Returns null.
+     * Returns empty string.
      *
      * @param columnIndex (1,2,...)
-     * @return null
+     * @return empty string
      */
     @Override
     public String getSchemaName(int columnIndex) {
-        return null;
+        return "";
     }
 
     /**
-     * Returns null.
+     * Returns empty string.
      *
      * @param columnIndex (1,2,...)
-     * @return null
+     * @return empty string
      */
     @Override
     public String getTableName(int columnIndex) {
-        return null;
+        return "";
     }
 
     // ---- unsupported / result set -----------------------------------

h2/src/test/org/h2/test/unit/TestTools.java

@@ -244,11 +244,11 @@ public class TestTools extends TestDb {
         assertTrue(rs.getMetaData().isSearchable(1));
         assertTrue(rs.getMetaData().isSigned(1));
         assertFalse(rs.getMetaData().isWritable(1));
-        assertEquals(null, rs.getMetaData().getCatalogName(1));
+        assertEquals("", rs.getMetaData().getCatalogName(1));
         assertEquals(null, rs.getMetaData().getColumnClassName(1));
         assertEquals("NULL", rs.getMetaData().getColumnTypeName(1));
-        assertEquals(null, rs.getMetaData().getSchemaName(1));
-        assertEquals(null, rs.getMetaData().getTableName(1));
+        assertEquals("", rs.getMetaData().getSchemaName(1));
+        assertEquals("", rs.getMetaData().getTableName(1));
         assertEquals(ResultSet.HOLD_CURSORS_OVER_COMMIT, rs.getHoldability());
         assertEquals(1, rs.getColumnCount());