我想更新一个表以指示某些行是其他行的父表，因此我在表中添加了“父代”列。以下查询查找所有父母：

SELECT ca1.id, ca2.id 
FROM contactassociations ca1
JOIN contactassociations ca2 ON (ca1.contactid = ca2.contactid)
where ca1.entitytable = 'EMPLOYER' AND
ca2.entitytable = 'CLIENT';

但是当我尝试修改该语法以进行更新时，它不起作用：

UPDATE contactassociations ca1
SET    ca1.parentid = ca2.id
JOIN  contactassociations ca2 ON (ca1.contactid = ca2.contactid)
WHERE ca1.entitytable = 'EMPLOYER' AND ca2.entitytable = 'CLIENT';

我得到：

Error starting at line 6 in command:
UPDATE contactassociations ca1
SET    ca1.parentid = ca2.id
JOIN  contactassociations ca2 ON (ca1.contactid = ca2.contactid)
WHERE ca1.entitytable = 'EMPLOYER' AND ca2.entitytable = 'CLIENT'
Error at Command Line:7 Column:28
Error report:
SQL Error: ORA-00933: SQL command not properly ended
00933. 00000 -  "SQL command not properly ended"
*Cause:    
*Action:

请注意，第7行第28列是“ SET”行的结尾。