MySql 中的 DELETE 真差劲...
这样写正常:
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SELECT   id   FROM   tree   WHERE   father!=0   AND   father   NOT   IN   (SELECT   id   FROM   tree   );

这样写出错:
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DELETE   FROM   tree   WHERE   father!=0   AND   father   NOT   IN   (SELECT   id   FROM   tree   );

ERROR   1093   (HY000):   You   can 't   specify   target   table   'tree   '   for   update   in   FROM   clause



------解决方案--------------------
右侧中写的相当明确：目前，您不能从一个表中删除，同时又在子查询中从同一个表中选择
------解决方案--------------------
呵呵~~~~~~~
------解决方案--------------------
DELETE FROM tree WHERE father!=0 AND father NOT IN (SELECT id FROM tree );
这样的sql在什么数据库会执行？
都应该不会执行的。
------解决方案--------------------
13.2.1. DELETE语法
单表语法：

DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name
[WHERE where_definition]
[ORDER BY ...]
[LIMIT row_count]
多表语法：

DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
tbl_name[.*] [, tbl_name[.*] ...]
FROM table_references
[WHERE where_definition]
或：

DELETE [LOW_PRIORITY] [QUICK] [IGNORE]
FROM tbl_name[.*] [, tbl_name[.*] ...]
USING table_references
[WHERE where_definition]