Oracle 多表数据修改问题

[z273894270]

现有SQL语句

UPDATE (SELECT a.volumeid, a.volume, a.newcasenum, b.casenum,
               b.volumeid AS str
          FROM volume a, propdat b
         WHERE a.volumeid IS NULL AND a.volume = b.casenum)
   SET volumeid = str

括号里查询结果显示为
VOLUMEID VOLUME NEWCASENUM CASENUM STR

null F-7-1277 9610135046 F-7-1277 656424162
null F-7-1277 9610135046 F-7-1277 656424162
null F-7-1277 9610135046 F-7-1277 656424162
null F-7-1277 9610135046 F-7-1277 656424162
null F-7-1277 9610135046 F-7-1277 656424162
null F-7-1277 9610135046 F-7-1277 656424162

现在想把str的数值赋值到volumeid里 报错

报错提示为cannot modify a column which maps to a non key-preserved tabl
求大神们给个可以解决方法或代码的SQL语句 怎么才能蒋STR里的值赋值到volumeid里 谢谢

[guanghuiy]

[code
UPDATE volume a SET a.volumeid=(SELECT b.volumeid FROM propdat where a.volumeid IS NULL AND a.volume = b.casenum);
/code]

个人理解，不知道是不是楼主要的。

[guanghuiy]

[code
UPDATE volume a SET a.volumeid=(SELECT b.volumeid FROM propdat where a.volumeid IS NULL AND a.volume = b.casenum);

[007-x]

试试这个呢

UPDATE   volume a
   SET   volumeid =
            (SELECT   b.volumeid
               FROM   propdat b
              WHERE       a.volumeid IS NULL
                      AND a.volume = b.casenum
                      AND ROWNUM = 1)
 WHERE   EXISTS (SELECT   1
                   FROM   propdat c
                  WHERE   a.volumeid IS NULL AND a.volume = c.casenum)