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/* Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
#ifndef SQL_UPDATE_INCLUDED
#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;
class THD;
typedef class st_select_lex SELECT_LEX;
typedef class st_select_lex_unit SELECT_LEX_UNIT;
bool check_unique_table(THD *thd, TABLE_LIST *table_list);
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:
ha_rows found{0}, updated{0};
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() override
{
return &multiupdate_prelocking_strategy;
}
bool processing_as_multitable_update_prohibited(THD *thd);
bool is_multitable() const { return multitable; }
void set_as_multitable() { multitable= true; }
void get_dml_stat (ha_rows &found, ha_rows &changed) override
{
found= this->found;
changed= this->updated;
}
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 */
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