If a table is the right operand of a LEFT JOIN, then any column of that

table can be NULL even if that column as a NOT NULL constraint.
Fix for ticket [6f2222d550f5b0ee7ed].

FossilOrigin-Name: 6f6fcbe4736b9468a495c684d5eebc8bfe5c566a

src/expr.c

@@ -1414,7 +1414,8 @@ int sqlite3ExprCanBeNull(const Expr *p){
       return 0;
     case TK_COLUMN:
       assert( p->pTab!=0 );
-      return p->iColumn>=0 && p->pTab->aCol[p->iColumn].notNull==0;
+      return ExprHasProperty(p, EP_CanBeNull) ||
+             (p->iColumn>=0 && p->pTab->aCol[p->iColumn].notNull==0);
     default:
       return 1;
   }