oracle开发学习篇之集合函数

集合函数;
declare
        type list_nested is table of varchar2(100) not null;
        v_all list_nested := list_nested('changan','hubei','shanghai','beijing','Android','Java-Android');
BEGIN
        v_all.delete(1);
        for x in v_all.first .. v_all.last loop
            dbms_output.put_line(v_all(x));
        end loop;
        --dbms_output.put_line('list leng:' || v_all.count );
end;
/

declare
        type list_nested is table of varchar2(100) not null;
        v_all list_nested := list_nested('changan','hubei','shanghai','beijing','Android','Java-Android');
BEGIN
        v_all.delete(1,3); --指定删除索引范围的数据;
        for x in v_all.first .. v_all.last loop
            dbms_output.put_line(v_all(x));
        end loop;
        dbms_output.put_line('list leng:' || v_all.count );
end;
/

declare
        type list_nested is table of varchar2(100) not null;
        v_all list_nested := list_nested('changan','hubei','shanghai','beijing','Android','Java-Android');
BEGIN
        if v_all.EXISTS(1) then
            dbms_output.put_line('索引为1的数据存在');
        end if;
        if not v_all.EXISTS(10) then
            dbms_output.put_line('索引为10的数据不存在');
        end if;
    end;
/

declare
        type list_nested is table of varchar2(100) not null;
        v_all list_nested := list_nested('FireFox','firefox.com','www.firefox.com');
begin
        dbms_output.put_line('原始长度' || v_all.count);
        v_all.extend(2);
        dbms_output.put_line('扩充之后长度' || v_all.count);
        v_all(4) := 'www.google.com';
        v_all(5) := 'Google.com';
        for x in v_all.first  .. v_all.last loop
            dbms_output.put_line(v_all(x));
        end loop;
    end;
/

范例
    扩充集合长度，并使用已有内容填充
declare
        type list_nested is table of varchar2(100) not null;
        v_all list_nested := list_nested('FireFox','firefox.com','www.firefox.com');
begin
        dbms_output.put_line('原始长度' || v_all.count);
        v_all.extend(2 , 3);
        dbms_output.put_line('扩充之后长度' || v_all.count);
        for x in v_all.first  .. v_all.last loop
            dbms_output.put_line(v_all(x));
        end loop;
    end;
/

范例
    集合函数count limit
declare
    type list_varray is  varray(20) of varchar2(100);
    v_info list_varray := list_varray('firefox.com','www.firefox.com','www.oracle.com');
begin
    dbms_output.put_line('数组集合的最大长度' || v_info.limit);
    dbms_output.put_line('数组集合的数据量' || v_info.count);
end;
/

declare
        type info_index is table of varchar2(20) index by PLS_INTEGER;
        v_info info_index;
        v_foot number;
begin
        v_info(1) := 'FireFox';
        v_info(10) := 'Java';
        v_info(-10) := 'oracle';
        v_info(-20) := 'EJB';
        v_info(30) := 'Android';
        v_foot := v_info.first;
        while (v_info.exists(v_foot)) loop
            dbms_output.put_line('v_info (' || v_foot ||') = ' || v_info(v_foot);
            v_foot := v_info.next(v_foot) ;
        end loop;
    end;
/ 

declare
        type info_index is table of varchar2(20) index by PLS_INTEGER;
        v_info info_index;
        v_foot number;
begin
        v_info(1) := 'FireFox';
        v_info(10) := 'Java';
        v_info(-10) := 'oracle';
        v_info(-20) := 'EJB';
        v_info(30) := 'Android';
        DBMS_OUTPUT.put_line('索引为10的下一个索引是:' || v_info.next(10));
        dbms_output.put_line('索引为-10的上一个索引是:' || v_info.prior(-10));
    end;
/ 

declare
        type list_varray is varray(8) of varchar2(50);
        v_info list_varray :=  list_varray('FireFox','www.FireFox','www.Google.com','EJB');
begin
        dbms_output.put_line();
        for x in v_info.first .. v_info.last loop
                dbms_output.put_line(v_info(x));
        end loop;
    end;
/
declare
        type list_varray is varray(8) of varchar2(100);
        v_info list_varray := list_varray('FireFox','www.firefox.com','oracle','oracle_username');
begin
        dbms_output.put_line('删除集合之前的数量:' || v_info.count);
        v_info.trim; -- 删除一个数据;
        dbms_output.put_line('v_info.trim 删除集合之后的数据量 :' || v_info.count);
        v_info.trim(2); -- 删除2个数据;
        dbms_output.put_line('v_info.trim(2) 删除集合之后的数据量 :' || v_info.count);
        for x in v_info.first .. v_info.last loop
            dbms_output.put_line(v_info(x));
        end loop;
    end;
/