From 0a9633ee62489a56f6122be920359007bbc0bfe2 Mon Sep 17 00:00:00 2001
From: Sergei Petrunia <psergey@askmonty.org>
Date: Sat, 7 Mar 2020 01:26:28 +0300
Subject: [PATCH] Basic LEX::print function that supports UPDATEs

---
 sql/sql_lex.cc | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
 sql/sql_lex.h  |  1 +
 2 files changed, 65 insertions(+)

diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 3ab1a46f95d..12b266508d0 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -3514,6 +3514,70 @@ bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
 }
 
 
+/*
+  @brief
+    Print the whole statement
+
+    @param str         Print into this string
+    @param query_type  Flags describing how to print
+
+  @detail
+    The intent is to allow to eventually print back any query.
+
+    This is useful e.g. for storage engines that take over diferrent kinds of
+    queries
+*/
+
+void LEX::print(String *str, enum_query_type query_type)
+{
+  if (sql_command == SQLCOM_UPDATE)
+  {
+    SELECT_LEX *sel= first_select_lex();
+    str->append(STRING_WITH_LEN("UPDATE "));
+    if (ignore)
+      str->append(STRING_WITH_LEN("IGNORE "));
+    // table name
+    str->append(query_tables->alias);
+    str->append(STRING_WITH_LEN(" SET "));
+    // print item assignments
+    List_iterator<Item> it(sel->item_list);
+    List_iterator<Item> it2(value_list);
+    Item *col_ref, *value;
+    bool first= true;
+    while ((col_ref= it++) && (value= it2++))
+    {
+      if (first)
+        first= false;
+      else
+        str->append(STRING_WITH_LEN(", "));
+      col_ref->print(str, query_type);
+      str->append(STRING_WITH_LEN("="));
+      value->print(str, query_type);
+    }
+
+    str->append(STRING_WITH_LEN(" WHERE "));
+    sel->where->print(str, query_type);
+
+    if (sel->order_list.elements)
+    {
+      str->append(STRING_WITH_LEN(" ORDER BY "));
+      for (ORDER *ord= sel->order_list.first; ord; ord= ord->next)
+      {
+        if (ord != sel->order_list.first)
+          str->append(STRING_WITH_LEN(", "));
+        (*ord->item)->print(str, query_type);
+      }
+    }
+    if (sel->select_limit)
+    {
+      str->append(STRING_WITH_LEN(" LIMIT "));
+      sel->select_limit->print(str, query_type);
+    }
+  }
+  else
+    DBUG_ASSERT(0); // Not implemented yet
+}
+
 void st_select_lex_unit::print(String *str, enum_query_type query_type)
 {
   if (with_clause)
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index c75833ae282..84be6e43eaf 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -3264,6 +3264,7 @@ public:
   void reset_arena_for_set_stmt(Query_arena *backup);
   void free_arena_for_set_stmt();
 
+  void print(String *str, enum_query_type qtype);
   List<Item_func_set_user_var> set_var_list; // in-query assignment list
   List<Item_param>    param_list;
   List<LEX_CSTRING>   view_list; // view list (list of field names in view)