diff options
Diffstat (limited to 'sql/sql_union.cc')
| -rw-r--r-- | sql/sql_union.cc | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/sql/sql_union.cc b/sql/sql_union.cc new file mode 100644 index 00000000000..a06c8f87cf0 --- /dev/null +++ b/sql/sql_union.cc @@ -0,0 +1,217 @@ +/* Copyright (C) 2000 MySQL AB + + 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; either version 2 of the License, or + (at your option) any later version. + + 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + + +/* + UNION of select's + UNION's were introduced by Monty and Sinisa <sinisa@mysql.com> +*/ + + +#include "mysql_priv.h" +#include "sql_select.h" + + +int mysql_union(THD *thd, LEX *lex) +{ + SELECT_LEX *sl, *last_sl; + ORDER *order; + List<Item> item_list; +/* TABLE_LIST *s=(TABLE_LIST*) lex->select_lex.table_list.first; */ + TABLE *table; + TABLE_LIST *first_table, result_table_list; + TMP_TABLE_PARAM tmp_table_param; + select_result *result; + select_union *union_result; + int res; + uint elements; + DBUG_ENTER("mysql_union"); + + /* Find last select part as it's here ORDER BY and GROUP BY is stored */ + elements= lex->select_lex.item_list.elements; + for (last_sl= &lex->select_lex; + last_sl->next; + last_sl=last_sl->next) + { + if (elements != last_sl->next->item_list.elements) + { + my_error(ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT,MYF(0)); + return -1; + } + } + + order = (ORDER *) last_sl->order_list.first; + { + Item *item; + List_iterator<Item> it(lex->select_lex.item_list); + + /* Create a list of items that will be in the result set */ + first_table= (TABLE_LIST*) lex->select_lex.table_list.first; + while ((item= it++)) + if (item_list.push_back(item)) + DBUG_RETURN(-1); + if (setup_fields(thd,first_table,item_list,0,0,1)) + DBUG_RETURN(-1); + } + bzero((char*) &tmp_table_param,sizeof(tmp_table_param)); + tmp_table_param.field_count=elements; + if (!(table=create_tmp_table(thd, &tmp_table_param, item_list, + (ORDER*) 0, !lex->union_option, + 1, 0, + (lex->select_lex.options | thd->options | + TMP_TABLE_ALL_COLUMNS)))) + DBUG_RETURN(-1); + table->file->extra(HA_EXTRA_WRITE_CACHE); + table->file->extra(HA_EXTRA_IGNORE_DUP_KEY); + bzero((char*) &result_table_list,sizeof(result_table_list)); + result_table_list.db= (char*) ""; + result_table_list.real_name=result_table_list.name=(char*) "union"; + result_table_list.table=table; + + if (!(union_result=new select_union(table))) + { + res= -1; + goto exit; + } + for (sl= &lex->select_lex; sl; sl=sl->next) + { + thd->offset_limit=sl->offset_limit; + thd->select_limit=sl->select_limit+sl->offset_limit; + if (thd->select_limit < sl->select_limit) + thd->select_limit= HA_POS_ERROR; // no limit + if (thd->select_limit == HA_POS_ERROR) + sl->options&= ~OPTION_FOUND_ROWS; + + res=mysql_select(thd,(TABLE_LIST*) sl->table_list.first, + sl->item_list, + sl->where, + sl->ftfunc_list, + (ORDER*) 0, + (ORDER*) sl->group_list.first, + sl->having, + (ORDER*) NULL, + sl->options | thd->options | SELECT_NO_UNLOCK, + union_result); + if (res) + goto exit; + } + if (union_result->flush()) + { + res= 1; // Error is already sent + goto exit; + } + delete union_result; + + /* + Sinisa, we must also be able to handle + CREATE TABLE ... and INSERT ... SELECT with unions + + To do this, it's probably best that we add a new handle_select() function + which takes 'select_result' as parameter and let this internally handle + SELECT with and without unions. + */ + + if (lex->exchange) + { + if (lex->exchange->dumpfile) + result=new select_dump(lex->exchange); + else + result=new select_export(lex->exchange); + } + else + result=new select_send(); + res =-1; + if (result) + { + /* Create a list of fields in the temporary table */ + List_iterator<Item> it(item_list); + Field **field; + List<Item_func_match> ftfunc_list; + ftfunc_list.empty(); + + for (field=table->field ; *field ; field++) + { + (void) it++; + (void) it.replace(new Item_field(*field)); + } + if (!thd->fatal_error) // Check if EOM + res=mysql_select(thd,&result_table_list, + item_list, NULL, ftfunc_list, order, + (ORDER*) NULL, NULL, (ORDER*) NULL, + thd->options, result); + if (res) + result->abort(); + delete result; + } + +exit: + free_tmp_table(thd,table); + DBUG_RETURN(res); +} + + +/*************************************************************************** +** store records in temporary table for UNION +***************************************************************************/ + +select_union::select_union(TABLE *table_par) + :table(table_par) +{ + bzero((char*) &info,sizeof(info)); + /* + We can always use DUP_IGNORE because the temporary table will only + contain a unique key if we are using not using UNION ALL + */ + info.handle_duplicates=DUP_IGNORE; +} + +select_union::~select_union() +{ +} + +int select_union::prepare(List<Item> &list) +{ + return 0; +} + +bool select_union::send_data(List<Item> &values) +{ + if (thd->offset_limit) + { // using limit offset,count + thd->offset_limit--; + return 0; + } + fill_record(table->field,values); + return write_record(table,&info) ? 1 : 0; +} + +bool select_union::send_eof() +{ + return 0; +} + +bool select_union::flush() +{ + int error,error2; + error=table->file->extra(HA_EXTRA_NO_CACHE); + if (error) + { + table->file->print_error(error,MYF(0)); + ::send_error(&thd->net); + return 1; + } + return 0; +} |