Fix for bug#9897: Views: 'Check Table' crashes MySQL, with a view and a table in the statement

   thd->lex->derived_tables should be zero(it may be changed if we open a view)

mysql-test/r/check.result

@@ -5,3 +5,12 @@ insert into t1 values (200000);
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 drop table t1;
+Create table t1(f1 int);
+Create table t2(f1 int);
+Create view v1 as Select * from t1;
+Check Table v1,t2;
+Table	Op	Msg_type	Msg_text
+test.v1	check	status	OK
+test.t2	check	status	OK
+drop view v1;
+drop table t1, t2;

mysql-test/t/check.test

@@ -22,3 +22,15 @@ connection con1;
 reap;
 drop table t1;
 
+#
+# Bug #9897  Views: 'Check Table' crashes MySQL, with a view and a table 
+# in the statement
+#
+
+connection default;
+Create table t1(f1 int);
+Create table t2(f1 int);
+Create view v1 as Select * from t1;
+Check Table v1,t2;
+drop view v1;
+drop table t1, t2;

sql/sql_table.cc

@@ -2342,6 +2342,13 @@ send_result_message:
     }
     close_thread_tables(thd);
     table->table=0;				// For query cache
+    /*
+      thd->lex->derived_tables may be set to non zero value if we open 
+      a view. It is necessary to clear thd->lex->derived_tables flag 
+      to prevent processing of derived tables during next open_and_lock_tables
+      if next table is a real table.
+    */
+    thd->lex->derived_tables= 0;
     if (protocol->write())
       goto err;
   }