bulk collect 在KingbaseES和Oracle的使用方法比较
作者:互联网
概述
BULK COLLECT 子句会批量检索结果,即一次性将结果集绑定到一个集合变量中,并从SQL引擎发送到PL/SQL引擎。通常可以在SELECT INTO、FETCH INTO以及RETURNING INTO子句中使用BULK COLLECT。
Oracle 使用 bulk collect 子句的用例
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BULK COLLECT批量绑定 支持复合类型内部的集合类型
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FETCH数据批量绑定
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RETURNING 子句的批量绑定 不支持 INSERT returning 使用集合类型
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动态SQL批量绑定 不支持动态 INSERT 使用集合类型
#创建自定义数据类型 —— 集合类型、复合类型 create type numberlist is table of number; create type rec_data is object ( ID integer, nums numberlist ); #创建用例数据表 create table t01 (id) as select level as id from dual connect by LEVEL <= 100; #Oracle使用bulk collect子句的例子 declare v_numlst numberlist; v_recdat rec_data ; CURSOR cur_dat IS select id from t01; begin /*在SELECT INTO中使用BULK COLLECT*/ begin select id bulk collect into v_numlst from t01 where id <= 10; dbms_output.put_line('v_numlst: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*使用 BULK COLLECT INTO 嵌套的集合类型*/ begin select id bulk collect into v_recdat.NUMS from t01 where id <= 20; dbms_output.put_line('v_recdat.NUMS: ' || v_recdat.NUMS.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*嵌套的集合类型变量赋值*/ begin v_recdat.NUMS := v_numlst; dbms_output.put_line('v_recdat.NUMS: ' || v_recdat.NUMS.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在FETCH INTO中使用BULK COLLECT*/ begin OPEN cur_dat; FETCH cur_dat BULK COLLECT INTO v_numlst limit 30; close cur_dat; dbms_output.put_line('fetch cursor: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在UPDATE RETURNING INTO中使用BULK COLLECT*/ begin update t01 set id = id + 100 where id <= 40 returning id bulk collect into v_numlst; rollback ; dbms_output.put_line('update returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在DELETE RETURNING INTO中使用BULK COLLECT*/ begin delete t01 returning id bulk collect into v_numlst; rollback; dbms_output.put_line('delete returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态SQL中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'select id from t01 where id <= 60 ' bulk collect into v_numlst; rollback; dbms_output.put_line('dynsql select: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态UPDATE中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'update t01 set id = id + 1 where id <= 70 returning id into :1' RETURNING bulk collect INTO v_numlst; rollback; dbms_output.put_line('dynsql update returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态DELETE中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'delete t01 where id <= 80 returning id into :1' RETURNING bulk collect INTO v_numlst; rollback; dbms_output.put_line('dynsql delete returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; dbms_output.put_line('End ;'); end; / v_numlst: 10 v_recdat.NUMS: 20 v_recdat.NUMS: 10 fetch cursor: 30 update returning: 40 delete returning: 50 dynsql select: 60 dynsql update returning: 70 dynsql delete returning: 80 End ; PL/SQL procedure successfully completed.
KingbaseES 使用 bulk collect 子句的用例
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BULK COLLECT批量绑定 不支持 复合类型内部的集合类型
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FETCH数据批量绑定
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RETURNING 子句的批量绑定 支持 INSERT returning 使用集合类型
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动态SQL批量绑定 支持动态 INSERT 使用集合类型
#创建自定义数据类型 —— 集合类型、复合类型 create type numberlist is table of number; create type rec_data is object ( ID integer, nums numberlist ); #创建用例数据表 create table t01 (id) as select level as id from dual connect by LEVEL <= 100; #Oracle使用bulk collect子句的例子 declare v_numlst numberlist; v_recdat rec_data ; CURSOR cur_dat IS select id from t01; begin /*在SELECT INTO中使用BULK COLLECT*/ begin select id bulk collect into v_numlst from t01 where id <= 10; dbms_output.put_line('v_numlst: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*使用 BULK COLLECT INTO 嵌套的集合类型*/ begin select id bulk collect into v_recdat.NUMS from t01 where id <= 20; dbms_output.put_line('v_recdat.NUMS: ' || v_recdat.NUMS.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*嵌套的集合类型变量赋值*/ begin v_recdat.NUMS := v_numlst; dbms_output.put_line('v_recdat.NUMS: ' || v_recdat.NUMS.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在FETCH INTO中使用BULK COLLECT*/ begin OPEN cur_dat; FETCH cur_dat BULK COLLECT INTO v_numlst limit 30; close cur_dat; dbms_output.put_line('fetch cursor: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在INERT RETURNING INTO中使用BULK COLLECT*/ begin insert into t01 select * from t01 where id <=35 returning id bulk collect into v_numlst; rollback; dbms_output.put_line('insert returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在UPDATE RETURNING INTO中使用BULK COLLECT*/ begin update t01 set id = id + 100 where id <= 40 returning id bulk collect into v_numlst; rollback ; dbms_output.put_line('update returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在DELETE RETURNING INTO中使用BULK COLLECT*/ begin delete t01 returning id bulk collect into v_numlst; rollback; dbms_output.put_line('delete returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态SQL中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'select id from t01 where id <= 60 ' bulk collect into v_numlst; rollback; dbms_output.put_line('dynsql select: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态INSERT中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'insert into t01 select * from t01 where id<=65 returning id' RETURNING bulk collect INTO v_numlst; rollback; dbms_output.put_line('dynsql insert returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态UPDATE中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'update t01 set id = id + 1 where id <= 70 returning id into :1' RETURNING bulk collect INTO v_numlst; rollback; dbms_output.put_line('dynsql update returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; /*在动态DELETE中使用BULK COLLECT*/ begin EXECUTE IMMEDIATE 'delete t01 where id <= 80 returning id into :1' RETURNING bulk collect INTO v_numlst; rollback; dbms_output.put_line('dynsql delete returning: ' || v_numlst.COUNT); exception when others then dbms_output.put_line(sqlerrm); end; dbms_output.put_line('End ;'); end; / ANONYMOUS BLOCK v_numlst: 10 cannot mix between single row and multi-row (BULK) in INTO list v_recdat.NUMS: 10 fetch cursor: 30 insert returning: 35 update returning: 40 delete returning: 50 dynsql select: 60 dynsql insert returning: 65 dynsql update returning: 70 dynsql delete returning: 80 End ;
总结
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BULK COLLECT INTO 的目标对象必须是集合类型。
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limit减少内存占用,如果数据量较大一次性全部加载到内存中,对PGA来说压力太大,可采用limit的方法一次加载一定数量的数据,建议值通常为1000。 使用limit时注意,循环的时候如果用while cursor_name%found loop,对于最后一次fetch的数据量不足设定值,%found条件就会不成立,可以使用 集合变量.count > 0 作为判断条件。
标签:批量,子句,create,绑定,bulk,collect,类型,集合,KingbaseES 来源: https://www.cnblogs.com/kingbase/p/15982072.html