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



[解决办法]
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
[解决办法]
呵呵~~~~~~~
[解决办法]
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。
[解决办法]
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]