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

  • BULK COLLECT批量绑定 支持复合类型内部的集合类型

  • FETCH数据批量绑定

  • RETURNING 子句的批量绑定 不支持 INSERT returning 使用集合类型

  • 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

  • BULK COLLECT批量绑定 不支持 复合类型内部的集合类型

  • FETCH数据批量绑定

  • RETURNING 子句的批量绑定 支持 INSERT returning 使用集合类型

  • 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

  1. BULK COLLECT INTO 的目标对象必须是集合类型。

  2. 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。

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