1 files changed, 77 insertions, 12 deletions

diff --git a/sql/sql_update.h b/sql/sql_update.h
index 65e44d112a4..bd7d58cf97d 100644
--- a/sql/sql_update.h
+++ b/sql/sql_update.h
@@ -17,6 +17,8 @@
 #define SQL_UPDATE_INCLUDED
 
 #include "sql_class.h"                          /* enum_duplicates */
+#include "sql_cmd.h"                            // Sql_cmd_dml
+#include "sql_base.h"
 
 class Item;
 struct TABLE_LIST;
@@ -25,20 +27,83 @@ class THD;
 typedef class st_select_lex SELECT_LEX;
 typedef class st_select_lex_unit SELECT_LEX_UNIT;
 
-bool mysql_prepare_update(THD *thd, TABLE_LIST *table_list,
-                          Item **conds, uint order_num, ORDER *order);
 bool check_unique_table(THD *thd, TABLE_LIST *table_list);
-int mysql_update(THD *thd,TABLE_LIST *tables,List<Item> &fields,
-		 List<Item> &values,COND *conds,
-		 uint order_num, ORDER *order, ha_rows limit,
-                 bool ignore, ha_rows *found_return, ha_rows *updated_return);
-bool mysql_multi_update(THD *thd, TABLE_LIST *table_list,
-                        List<Item> *fields, List<Item> *values,
-                        COND *conds, ulonglong options,
-                        enum enum_duplicates handle_duplicates, bool ignore,
-                        SELECT_LEX_UNIT *unit, SELECT_LEX *select_lex,
-                        multi_update **result);
 bool records_are_comparable(const TABLE *table);
 bool compare_record(const TABLE *table);
 
+/**
+   @class Sql_cmd_update - class used for any UPDATE statements
+
+   This class is derived from Sql_cmd_dml and contains implementations
+   for abstract virtual function of the latter such as precheck() and
+   prepare_inner(). It also overrides the implementation of execute_inner()
+   providing a special handling for single-table update statements that
+   are not converted to multi-table updates.
+   The class provides an object of the Multiupdate_prelocking_strategy class
+   for the virtual function get_dml_prelocking_strategy().
+*/
+class Sql_cmd_update final : public Sql_cmd_dml
+{
+public:
+  Sql_cmd_update(bool multitable_arg)
+    : orig_multitable(multitable_arg), multitable(multitable_arg)
+  {}
+
+  enum_sql_command sql_command_code() const override
+  {
+    return orig_multitable ? SQLCOM_UPDATE_MULTI : SQLCOM_UPDATE;
+  }
+
+  DML_prelocking_strategy *get_dml_prelocking_strategy()
+  {
+    return &multiupdate_prelocking_strategy;
+  }
+
+  bool processing_as_multitable_update_prohibited(THD *thd);
+
+  bool is_multitable() { return multitable; }
+
+  void set_as_multitable() { multitable= true; }
+
+protected:
+  /**
+    @brief Perform precheck of table privileges for update statements
+  */
+  bool precheck(THD *thd) override;
+
+  /**
+    @brief Perform context analysis for update statements
+  */
+  bool prepare_inner(THD *thd) override;
+
+  /**
+    @brief Perform optimization and execution actions needed for updates
+  */
+  bool execute_inner(THD *thd) override;
+
+private:
+
+  /**
+    @brief Special handling of single-table updates after prepare phase
+  */
+  bool update_single_table(THD *thd);
+
+  /* Original value of the 'multitable' flag set by constructor */
+  const bool orig_multitable;
+
+  /*
+    True if the statement is a multi-table update or converted to such.
+    For a single-table update this flag is set to true if the statement
+    is supposed to be converted to multi-table update.
+  */
+  bool multitable;
+
+  /* The prelocking strategy used when opening the used tables */
+  Multiupdate_prelocking_strategy multiupdate_prelocking_strategy;
+
+ public:
+  /* The list of the updating expressions used in the set clause */
+  List<Item> *update_value_list;
+};
+
 #endif /* SQL_UPDATE_INCLUDED */