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93d270c3a4
Adding support for cursors on prepared statements.
- SQL Standard way:
DECLARE c CURSOR FOR stmt;
PREPARE stmt FROM 'SELECT ?';
OPEN c USING 1;
- Oracle-style way with SYS_REFCURSOR variables:
DECLARE
c SYS_REFCURSOR;
BEGIN
OPEN c FOR 'SELECT ?' USING 1;
95 lines
3 KiB
C++
95 lines
3 KiB
C++
/*
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Copyright (c) 2025, MariaDB Corporation.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
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#ifdef MYSQL_SERVER
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#include "mariadb.h"
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#include "sql_class.h"
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bool sp_cursor::check_for_open(THD *thd, bool check_open_cursor_counter) const
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{
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if (server_side_cursor)
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{
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my_message(ER_SP_CURSOR_ALREADY_OPEN,
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ER_THD(thd, ER_SP_CURSOR_ALREADY_OPEN),
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MYF(0));
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return true;
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}
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if (check_open_cursor_counter &&
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thd->open_cursors_counter() >= thd->variables.max_open_cursors)
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{
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my_error(ER_TOO_MANY_OPEN_CURSORS, MYF(0),
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thd->variables.max_open_cursors);
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return true;
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}
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return false;
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}
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/*
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Append a new element into the array.
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@return NULL Type_ref_null (with is_null()==true) on error (EOM).
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@return not-NULL Type_ref_null on success
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*/
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Type_ref_null sp_cursor_array::append(THD *thd)
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{
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if (Dynamic_array::append(sp_cursor_array_element()))
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{
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DBUG_ASSERT(thd->is_error());
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return Type_ref_null();
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}
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return Type_ref_null((ulonglong) size() - 1);
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}
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/*
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Find a cursor by reference.
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@param thd - the current THD
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@param ref - the field behind a SYS_REFCURSOR SP variable
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@param for_open - if the cursor is needed for OPEN rather than FETCH/CLOSE,
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so a new cursor is appended if not found.
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*/
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sp_cursor_array_element *sp_cursor_array::get_cursor_by_ref(THD *thd,
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Field *ref_field,
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bool for_open)
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{
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Type_ref_null ref= ref_field->val_ref(thd);
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if (ref < (ulonglong) elements())
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return &at((size_t) ref.value());// "ref" points to an initialized sp_cursor
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if (!for_open)
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return nullptr;
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/*
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We are here when:
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- The reference ref.is_null() is true, meaning that the
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ref_field's SP variable is not linked to any cursors in "this" array:
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* it is the very first "OPEN .. FOR STMT" command for ref_field.
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* or the ref_field's SP variable was set to NULL explicitly.
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- Or ref_field for some reasons returned a cursor offset outside
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or the range [0..elements()-1].
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*/
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if (((ref= find_unused()).is_null() && (ref= append(thd)).is_null()) ||
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ref_field->store_ref(ref, true/*no_conversions*/))
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return nullptr;
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at((size_t) ref.value()).reset(thd, 1/*ref count*/);
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return &at((size_t) ref.value());
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}
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#endif // MYSQL_SERVER
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