Question

我在一个名为＆＃34;数字＆＃34;的表格中有一个9位数的ID列表，其中一列名为＆＃34; ID＆＃34;。我想在子查询中使用它们来查找名为artransaction的表中的特定行。问题是在artransaction的transactionid列中，它在9位ID前面有一个零。

所以，如果我这样做：

select * from artransaction
where transactionid in lpad((select id from numbers where rownum=1),10,'0');

结果回来了。但如果我这样做：

select * from artransaction
where transactionid in lpad((select id from numbers),10,'0');

它说＆＃34;单行子查询返回多行＆＃34;

是否可以在LPAD中放入子查询？

Answer 1

您应该重写该查询。这是一个基于Scott的EMP表的示例 - 我想选择包含COMM的行，看起来像那些存储在NUMBERS表中的行。

SQL> select ename, comm from emp order by ename;

ENAME            COMM
---------- ----------
ALLEN             300
BLAKE
CLARK
FORD
JAMES
JONES
KING
MARTIN           1400
MILLER
SMITH
TURNER              0
WARD              500

12 rows selected.

SQL>

示例NUMBERS表：

SQL> create table numbers (comm number);

Table created.

SQL> insert into numbers values (14);

1 row created.

SQL> insert into numbers values (50);

1 row created.

SQL> insert into numbers values (3);

1 row created.

SQL> select * From numbers;

      COMM
----------
        14
        50
         3

SQL>

测试：

SQL> -- This one will work because of the ROWNUM = 1 condition, which returns a single value
SQL> select * from emp
  2  where comm in rpad((select comm from numbers where rownum = 1), 4, '0');

     EMPNO ENAME      JOB              MGR HIREDATE          SAL       COMM     DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
      7654 MARTIN     SALESMAN        7698 28.09.1981       1250       1400         30

SQL> -- This will result in error because NUMBERS contain several values
SQL> select * from emp
  2  where comm in rpad((select comm from numbers), 4, '0');
where comm in rpad((select comm from numbers), 4, '0')
                    *
ERROR at line 2:
ORA-01427: single-row subquery returns more than one row


SQL> -- So - rewrite it
SQL> select * from emp
  2  where comm in (select rpad(comm, 3, '0') from numbers);

     EMPNO ENAME      JOB              MGR HIREDATE          SAL       COMM     DEPTNO
---------- ---------- --------- ---------- ---------- ---------- ---------- ----------
      7521 WARD       SALESMAN        7698 22.02.1981       1250        500         30
      7499 ALLEN      SALESMAN        7698 20.02.1981       1600        300         30

SQL>

或者，应用于您的查询：

select * from artransaction
where transactionid in (select lpad(id, 10, '0') from numbers);

你能在LPAD中使用子查询吗？

1 个答案: