避免在 PL/SQL 中使用嵌套游标查询

源代码网整理以下　　declare
　　l_count　　 integer;
　　begin
　　dbms_output.put_line("<matrix>");
　　-- generate matrix of parts by country
　　for part in (select id,description from parts order by description) loop
　　dbms_output.put_line("<row>");
　　dbms_output.put_line("<cell>"part.description"</cell>");
　　for country in (select code from countries order by name) loop
　　select sum(cnt) into l_count from orders
　　where part_id = part.id and cc = country.code;
　　dbms_output.put_line("<cell>"nvl(l_count,0)"</cell>");
　　end loop;
　　dbms_output.put_line("</row>");
　　end loop;
　　dbms_output.put_line("</matrix>");
　　end;

源代码网整理以下　　declare
　　type part_tbl_type is table of parts%rowtype index by binary_integer;
　　part_tbl　　 part_tbl_type;
　　--
　　type country_tbl_type is table of countries%rowtype index by binary_integer;
　　country_tbl　　 country_tbl_type;
　　--
　　type cell_rec is record
　　(
　　part_id　　　　　orders.part_id%type,
　　cc　　　　　　　 orders.cc%type,
　　cnt　　　　　　　 orders.cnt%type
　　);
　　type cell_tbl_type is table of cell_rec index by binary_integer;
　　cell_tbl cell_tbl_type;
　　--
　　i pls_integer;
　　begin
　　-- build rows
　　for row in (select * from parts order by description) loop
　　part_tbl(part_tbl.count+1) := row;
　　end loop;
　　-- build columns
　　for col in (select * from countries order by name) loop
　　country_tbl(country_tbl.count+1) := col;
　　end loop;
　　-- build cells
　　for cell in (select part_id,cc,sum(cnt) from orders group by part_id,cc) loop
　　cell_tbl(cell_tbl.count+1) := cell;
　　end loop;
　　dbms_output.put_line("<matrix>");
　　-- generate matrix of parts by country
　　i := cell_tbl.first;
　　for row in part_tbl.first .. part_tbl.last loop
　　dbms_output.put_line("<row>");
　　dbms_output.put_line("<cell>"part_tbl(row).description"</cell>");
　　for col in country_tbl.first .. country_tbl.last loop
　　if cell_tbl(i).part_id = part_tbl(row).id
　　and cell_tbl(i).cc = country_tbl(col).code
　　then
　　dbms_output.put_line("<cell>"cell_tbl(i).cnt"</cell>");
　　i := i + 1;
　　else
　　dbms_output.put_line("<cell>0</cell>");
　　end if;
　　end loop;
　　dbms_output.put_line("</row>");
　　end loop;
　　dbms_output.put_line("</matrix>");
　　end;

源代码网整理以下　　declare
　　type part_id_tbl_type is table of parts.id%type;
　　type part_desc_tbl_type is table of parts.description%type;
　　part_id_tbl　　　　　part_id_tbl_type;
　　part_desc_tbl　　 part_desc_tbl_type;
　　--
　　type country_code_tbl_type is table of countries.code%type;
　　country_code_tbl　　 country_code_tbl_type;
　　--
　　type cell_cnt_tbl_type is table of orders.cnt%type;
　　cell_part_id_tbl　　 part_id_tbl_type;
　　cell_country_tbl　　 country_code_tbl_type;
　　cell_cnt_tbl　　　　　cell_cnt_tbl_type;
　　--
　　i pls_integer;
　　begin
　　-- gather rows
　　select id,description
　　bulk collect into part_id_tbl,part_desc_tbl
　　from parts
　　order by description;
　　-- gather columns
　　select code
　　bulk collect into country_code_tbl
　　from countries
　　order by name;
　　-- gather cells
　　select part_id,cc,sum(cnt)
　　bulk collect into cell_part_id_tbl,cell_country_tbl,cell_cnt_tbl
　　from orders
　　group by part_id,cc;
　　dbms_output.put_line("<matrix>");
　　-- generate matrix of parts by country
　　i := cell_cnt_tbl.first;
　　for row in part_id_tbl.first .. part_id_tbl.last loop
　　dbms_output.put_line("<row>");
　　dbms_output.put_line("<cell>"part_desc_tbl(row)"</cell>");
　　for col in country_code_tbl.first .. country_code_tbl.last loop
　　if cell_part_id_tbl(i) = part_id_tbl(row)
　　and cell_country_tbl(i) = country_code_tbl(col)
　　then
　　dbms_output.put_line("<cell>"cell_cnt_tbl(i)"</cell>");
　　i := i + 1;
　　else
　　dbms_output.put_line("<cell>0</cell>");
　　end if;
　　end loop;
　　dbms_output.put_line("</row>");
　　end loop;
　　dbms_output.put_line("</matrix>");