1 /* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved. 2 3 This program is free software; you can redistribute it and/or modify 4 it under the terms of the GNU General Public License, version 2.0, 5 as published by the Free Software Foundation. 6 7 This program is also distributed with certain software (including 8 but not limited to OpenSSL) that is licensed under separate terms, 9 as designated in a particular file or component or in included license 10 documentation. The authors of MySQL hereby grant you an additional 11 permission to link the program and your derivative works with the 12 separately licensed software that they have included with MySQL. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License, version 2.0, for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program; if not, write to the Free Software 21 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ 22 23 #ifndef SQL_CMD_DML_INCLUDED 24 #define SQL_CMD_DML_INCLUDED 25 26 #include "my_dbug.h" 27 #include "sql/sql_cmd.h" 28 29 struct LEX; 30 class Query_result; 31 32 class Sql_cmd_dml : public Sql_cmd { 33 public: 34 /// @return true if data change statement, false if not (SELECT statement) is_data_change_stmt()35 virtual bool is_data_change_stmt() const { return true; } 36 37 /** 38 Command-specific resolving (doesn't include LEX::prepare()) 39 40 @param thd Current THD. 41 42 @returns false on success, true on error 43 */ 44 virtual bool prepare(THD *thd); 45 46 /** 47 Execute this query once. 48 49 @param thd Thread handler 50 51 @returns false on success, true on error 52 */ 53 virtual bool execute(THD *thd); 54 is_dml()55 virtual bool is_dml() const { return true; } 56 is_single_table_plan()57 virtual bool is_single_table_plan() const { return false; } 58 59 protected: Sql_cmd_dml()60 Sql_cmd_dml() 61 : Sql_cmd(), lex(nullptr), result(nullptr), m_empty_query(false) {} 62 63 /// @return true if query is guaranteed to return no data 64 /** 65 @todo Also check this for the following cases: 66 - Empty source for multi-table UPDATE and DELETE. 67 - Check empty query expression for INSERT 68 */ is_empty_query()69 bool is_empty_query() const { 70 DBUG_ASSERT(is_prepared()); 71 return m_empty_query; 72 } 73 74 /// Set statement as returning no data set_empty_query()75 void set_empty_query() { m_empty_query = true; } 76 77 /** 78 Perform a precheck of table privileges for the specific operation. 79 80 @details 81 Check that user has some relevant privileges for all tables involved in 82 the statement, e.g. SELECT privileges for tables selected from, INSERT 83 privileges for tables inserted into, etc. This function will also populate 84 TABLE_LIST::grant with all privileges the user has for each table, which 85 is later used during checking of column privileges. 86 Note that at preparation time, views are not expanded yet. Privilege 87 checking is thus rudimentary and must be complemented with later calls to 88 SELECT_LEX::check_view_privileges(). 89 The reason to call this function at such an early stage is to be able to 90 quickly reject statements for which the user obviously has insufficient 91 privileges. 92 93 @param thd thread handler 94 95 @returns false if success, true if false 96 */ 97 virtual bool precheck(THD *thd) = 0; 98 99 /** 100 Perform the command-specific parts of DML command preparation, 101 to be called from prepare() 102 103 @param thd the current thread 104 105 @returns false if success, true if error 106 */ 107 virtual bool prepare_inner(THD *thd) = 0; 108 109 /** 110 The inner parts of query optimization and execution. 111 Single-table DML operations needs to reimplement this. 112 113 @param thd Thread handler 114 115 @returns false on success, true on error 116 */ 117 virtual bool execute_inner(THD *thd); 118 119 protected: 120 LEX *lex; ///< Pointer to LEX for this statement 121 Query_result *result; ///< Pointer to object for handling of the result 122 bool m_empty_query; ///< True if query will produce no rows 123 }; 124 125 #endif /* SQL_CMD_DML_INCLUDED */ 126