MDEV-37172 Server crashes in Item_func_nextval::update_table after INSERT to the table, that uses expression with nextval() as default

The issue was that unpack_vcol_info_from_frm() wrongly linked the used
sequence tables into tables->internal_tables when more than one sequence
table was used.

Other things:
- Fixed internal_table_exists() to take db into account.
  (This is making the code easier to read. As we where comparing
   pointers the old code also worked).

mysql-test/suite/sql_sequence/default.result

@@ -313,4 +313,37 @@ insert v1 values (default);
 ERROR HY000: The target table v1 of the INSERT is not insertable-into
 drop view v1;
 drop table t1;
+#
+# MDEV-37172 Server crashes in Item_func_nextval::update_table after
+# INSERT to the table, that uses expression with nextval() as default
+#
+create sequence s1;
+create sequence s2;
+create table t1 (id int default(nextval(s1)));
+create table t2 (id int default(nextval(s1)+nextval(s1)));
+create table t3 (id1 int default(nextval(s1)+nextval(s1)),
+id2 int default(nextval(s2)));
+insert t1 values ();
+select lastval(s1);
+lastval(s1)
+1
+select * from t1;
+id
+1
+insert t2 values ();
+select lastval(s1);
+lastval(s1)
+3
+select * from t2;
+id
+5
+insert t3 values ();
+select lastval(s1), lastval(s2);
+lastval(s1)	lastval(s2)
+5	1
+select * from t3;
+id1	id2
+9	1
+drop table t1,t2,t3;
+drop sequence s1,s2;
 # End of 10.6 tests

mysql-test/suite/sql_sequence/default.test

@@ -240,4 +240,27 @@ insert v1 values (default);
 drop view v1;
 drop table t1;
 
+--echo #
+--echo # MDEV-37172 Server crashes in Item_func_nextval::update_table after
+--echo # INSERT to the table, that uses expression with nextval() as default
+--echo #
+
+create sequence s1;
+create sequence s2;
+create table t1 (id int default(nextval(s1)));
+create table t2 (id int default(nextval(s1)+nextval(s1)));
+create table t3 (id1 int default(nextval(s1)+nextval(s1)),
+                 id2 int default(nextval(s2)));
+insert t1 values ();
+select lastval(s1);
+select * from t1;
+insert t2 values ();
+select lastval(s1);
+select * from t2;
+insert t3 values ();
+select lastval(s1), lastval(s2);
+select * from t3;
+drop table t1,t2,t3;
+drop sequence s1,s2;
+
 --echo # End of 10.6 tests

sql/sql_base.cc

@@ -4722,11 +4722,12 @@ bool table_already_fk_prelocked(TABLE_LIST *tl, LEX_CSTRING *db,
 
 
 static TABLE_LIST *internal_table_exists(TABLE_LIST *global_list,
-                                         const char *table_name)
+                                         TABLE_LIST *table)
 {
   do
   {
-    if (global_list->table_name.str == table_name)
+    if (global_list->table_name.str == table->table_name.str &&
+        global_list->db.str == table->db.str)
       return global_list;
   } while ((global_list= global_list->next_global));
   return 0;
@@ -4747,8 +4748,7 @@ add_internal_tables(THD *thd, Query_tables_list *prelocking_ctx,
     /*
       Skip table if already in the list. Can happen with prepared statements
     */
-    if ((tmp= internal_table_exists(global_table_list,
-                                    tables->table_name.str)))
+    if ((tmp= internal_table_exists(global_table_list, tables)))
     {
       /*
         Use the original value for the next local, used by the

sql/sql_parse.cc

@@ -8438,8 +8438,8 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
       }
     }
   }
-  /* Store the table reference preceding the current one. */
-  TABLE_LIST *UNINIT_VAR(previous_table_ref); /* The table preceding the current one. */
+  /* Store the table reference preceding the current in previous_table_ref */
+  TABLE_LIST *UNINIT_VAR(previous_table_ref);
   if (table_list.elements > 0 && likely(!ptr->sequence))
   {
     /*

sql/table.cc

@@ -3942,6 +3942,7 @@ unpack_vcol_info_from_frm(THD *thd, TABLE *table,
   LEX *old_lex= thd->lex;
   LEX lex;
   bool error;
+  TABLE_LIST *sequence, *last;
   DBUG_ENTER("unpack_vcol_info_from_frm");
 
   DBUG_ASSERT(vcol->expr == NULL);
@@ -3959,11 +3960,12 @@ unpack_vcol_info_from_frm(THD *thd, TABLE *table,
   if (unlikely(error))
     goto end;
 
-  if (lex.current_select->table_list.first[0].next_global)
+  if ((sequence= lex.current_select->table_list.first[0].next_global))
   {
-    /* We are using NEXT VALUE FOR sequence. Remember table name for open */
-    TABLE_LIST *sequence= lex.current_select->table_list.first[0].next_global;
-    sequence->next_global= table->internal_tables;
+    /* We are using NEXT VALUE FOR sequence. Remember table for open */
+    for (last= sequence ; last->next_global ; last= last->next_global)
+      ;
+    last->next_global= table->internal_tables;
     table->internal_tables= sequence;
   }