Question

在这种情况下，我想为表中的每一行生成重复的行。重复次数等于每行中的num_rows列。

public class AreaSelect extends AppCompatActivity {
TextView textView;
String union;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_area_select);

    textView = findViewById(R.id.tvUnion);

    Bundle extras = getIntent().getExtras();
    union = extras.getString("key");

    textView.setText(union);
}

预期产出：

create table test_create_rows(name varchar2(20), num_rows integer);

insert into test_create_rows values('Name1',3);
insert into test_create_rows values('Name2',4);
insert into test_create_rows values('Name3',1);

commit;

Answer 1

将cross apply子句与分层查询一起使用

select x.* 
from test_create_rows t
cross apply (
  select t.NAME, t.NUM_ROWS from dual
  connect by level <= t.num_rows
) x;

Answer 2

您可以尝试使用CTE Recursion

WITH CTE(name, num_rows,startnum) AS(
  SELECT name,num_rows,1 startnum
  FROM test_create_rows
  UNION ALL
  SELECT name,num_rows,(startnum + 1) as startnum
  FROM CTE
  WHERE (startnum + 1) <= num_rows
)
SELECT name ,num_rows
FROM CTE
order by name

<强> Results ：

|  NAME | NUM_ROWS |
|-------|----------|
| Name1 |        3 |
| Name1 |        3 |
| Name1 |        3 |
| Name2 |        4 |
| Name2 |        4 |
| Name2 |        4 |
| Name2 |        4 |
| Name3 |        1 |

如何基于单元格中的值创建重复行

2 个答案: