Index: driver/myodbc3.h
===================================================================
--- driver/myodbc3.h	(revision 422)
+++ driver/myodbc3.h	(working copy)
@@ -325,6 +325,7 @@
 {
   DBC FAR	*dbc;
   MYSQL_RES	*result;
+  my_bool       fake_result;
   MYSQL_ROW	array,result_array,current_values;
   MYSQL_ROW	(*fix_fields)(struct tagSTMT FAR* stmt,MYSQL_ROW row);
   MYSQL_FIELD	*fields;
Index: driver/catalog.c
===================================================================
--- driver/catalog.c	(revision 422)
+++ driver/catalog.c	(working copy)
@@ -334,6 +334,7 @@
         /* Return set of allowed Table owners */
         MYODBCDbgInfo( "%s", "Return set of table owners / Schema names" );
         stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+        stmt->fake_result= 1;
         stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLTABLES_owner_values,
                                                   sizeof(SQLTABLES_owner_values),
                                                   MYF(0));
@@ -351,6 +352,7 @@
         /* Return set of TableType qualifiers */
         MYODBCDbgInfo( "%s", "Return set of table types" );
         stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+        stmt->fake_result= 1;
         stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLTABLES_type_values,
                                                   sizeof(SQLTABLES_type_values),
                                                   MYF(0));
@@ -533,6 +535,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLTABLES_values,
                                               sizeof(SQLTABLES_values), 
@@ -861,6 +864,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLCOLUMNS_values,
                                               sizeof(SQLCOLUMNS_values), 
@@ -1039,6 +1043,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLSTAT_values,
                                               sizeof(SQLSTAT_values), 
@@ -1231,6 +1236,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLTABLES_priv_values,
                                               sizeof(SQLTABLES_priv_values), 
@@ -1405,6 +1411,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLCOLUMNS_priv_values,
                                               sizeof(SQLCOLUMNS_priv_values), 
@@ -1632,6 +1639,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLSPECIALCOLUMNS_values,
                                               sizeof(SQLSPECIALCOLUMNS_values), 
@@ -1753,6 +1761,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLPRIM_KEYS_values,
                                               sizeof(SQLPRIM_KEYS_values), 
@@ -2085,6 +2094,7 @@
     else /* NO FOREIGN KEY support from SERVER */
     {
         stmt->result=(MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+        stmt->fake_result= 1;
         stmt->result->eof=1;
     }  
     stmt->result->row_count= row_count;
@@ -2095,6 +2105,7 @@
     empty_set:
     MYODBCDbgInfo( "%s", "Can't match anything; Returning empty set" );
     stmt->result= (MYSQL_RES*) my_malloc(sizeof(MYSQL_RES),MYF(MY_ZEROFILL));
+    stmt->fake_result= 1;
     stmt->result->row_count= 0;
     stmt->result_array= (MYSQL_ROW) my_memdup((gptr) SQLFORE_KEYS_values,
                                               sizeof(SQLFORE_KEYS_values), 
Index: driver/info.c
===================================================================
--- driver/info.c	(revision 422)
+++ driver/info.c	(working copy)
@@ -1067,6 +1067,7 @@
 
   /* Set up result Data dictionary. */
   stmt->result= (MYSQL_RES *)my_malloc(sizeof(MYSQL_RES), MYF(MY_ZEROFILL));
+  stmt->fake_result= 1;
   stmt->result_array= (char **)my_malloc(sizeof(SQL_GET_TYPE_INFO_values),
                                          MYF(MY_FAE | MY_ZEROFILL));
 
Index: driver/handle.c
===================================================================
--- driver/handle.c	(revision 422)
+++ driver/handle.c	(working copy)
@@ -423,12 +423,16 @@
     if (fOption == SQL_RESET_PARAMS)
         MYODBCDbgReturnReturn( SQL_SUCCESS );
 
-    mysql_free_result(stmt->result);
+    if (!stmt->fake_result)
+      mysql_free_result(stmt->result);
+    else
+      x_free((gptr)stmt->result);
     x_free((gptr) stmt->fields);
     x_free((gptr) stmt->array);
     x_free((gptr) stmt->result_array);
     x_free((gptr) stmt->odbc_types);
     stmt->result= 0;
+    stmt->fake_result= 0;
     stmt->result_lengths= 0;
     stmt->fields= 0;
     stmt->array= 0;
Index: test/my_catalog.c
===================================================================
--- test/my_catalog.c	(revision 422)
+++ test/my_catalog.c	(working copy)
@@ -1172,6 +1172,51 @@
 }
 
 
+/**
+ Tests the non-error code paths in catalog.c that return an empty set to
+ make sure the resulting empty result sets at least indicate the right
+ number of columns.
+*/
+DECLARE_TEST(empty_set)
+{
+  SQLSMALLINT columns;
+
+  /* SQLTables(): no known table types. */
+  ok_stmt(hstmt, SQLTables(hstmt, NULL, SQL_NTS, NULL, SQL_NTS, NULL, SQL_NTS,
+                           (SQLCHAR *)"UNKNOWN", SQL_NTS));
+  ok_stmt(hstmt, SQLNumResultCols(hstmt, &columns));
+  is_num(columns, 5);
+  expect_stmt(hstmt, SQLFetch(hstmt), SQL_NO_DATA_FOUND);
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  /* SQLTables(): no tables found. */
+  ok_stmt(hstmt, SQLTables(hstmt, NULL, SQL_NTS, NULL, SQL_NTS,
+                           (SQLCHAR *)"no_such_table", SQL_NTS, NULL, SQL_NTS));
+  ok_stmt(hstmt, SQLNumResultCols(hstmt, &columns));
+  is_num(columns, 5);
+  expect_stmt(hstmt, SQLFetch(hstmt), SQL_NO_DATA_FOUND);
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  /* SQLColumns(): no table specified. */
+  ok_stmt(hstmt, SQLColumns(hstmt, NULL, SQL_NTS, NULL, SQL_NTS,
+                            NULL, SQL_NTS, NULL, SQL_NTS));
+  ok_stmt(hstmt, SQLNumResultCols(hstmt, &columns));
+  is_num(columns, 18);
+  expect_stmt(hstmt, SQLFetch(hstmt), SQL_NO_DATA_FOUND);
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  /* SQLStatistics(): no table specified. */
+  ok_stmt(hstmt, SQLStatistics(hstmt, NULL, SQL_NTS, NULL, SQL_NTS,
+                               NULL, SQL_NTS, 0, 0));
+  ok_stmt(hstmt, SQLNumResultCols(hstmt, &columns));
+  is_num(columns, 13);
+  expect_stmt(hstmt, SQLFetch(hstmt), SQL_NO_DATA_FOUND);
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  return OK;
+}
+
+
 BEGIN_TESTS
   ADD_TEST(my_columns_null)
   ADD_TEST(my_drop_table)
@@ -1189,6 +1234,7 @@
   ADD_TEST(tmysql_showkeys)
   ADD_TEST(t_sqltables)
   ADD_TEST(t_bug4518)
+  ADD_TEST(empty_set)
 END_TESTS
 
 
Index: test/my_use_result.c
===================================================================
--- test/my_use_result.c	(revision 422)
+++ test/my_use_result.c	(working copy)
@@ -70,8 +70,42 @@
 }
 
 
+/**
+ Bug #4657: "Don't Cache Results" crashes when using catalog functions
+*/
+DECLARE_TEST(t_bug4657)
+{
+  SQLCHAR     name[10];
+  SQLSMALLINT column_count;
+  SQLLEN      name_length;
+
+  ok_sql(hstmt, "DROP TABLE IF EXISTS t_bug4657");
+  ok_sql(hstmt, "CREATE TABLE t_bug4657 (a INT)");
+
+  ok_stmt(hstmt, SQLTables(hstmt, (SQLCHAR *)"", SQL_NTS,
+                           (SQLCHAR *)"", SQL_NTS,
+                           (SQLCHAR *)"", SQL_NTS,
+                           (SQLCHAR *)"TABLE,VIEW", SQL_NTS));
+
+  ok_stmt(hstmt, SQLNumResultCols(hstmt, &column_count));
+  is_num(column_count, 5);
+
+  ok_stmt(hstmt, SQLBindCol(hstmt, 3, SQL_C_CHAR, name, sizeof(name),
+                            &name_length));
+  expect_stmt(hstmt, SQLFetch(hstmt), SQL_NO_DATA_FOUND);
+
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_UNBIND));
+  ok_stmt(hstmt, SQLFreeStmt(hstmt, SQL_CLOSE));
+
+  ok_sql(hstmt, "DROP TABLE IF EXISTS t_bug4657");
+
+  return OK;
+}
+
+
 BEGIN_TESTS
   ADD_TEST(t_use_result)
+  ADD_TEST(t_bug4657)
 END_TESTS