DB_driver.php 中的 _protect_identifiers 函数疑问
/*** Protect Identifiers
*
* This function is used extensively by the Active Record class, and by
* a couple functions in this class.
* It takes a column or table name (optionally with an alias) and inserts
* the table prefix onto it.Some logic is necessary in order to deal with
* column names that include the path.Consider a query like this:
*
* SELECT * FROM hostname.database.table.column AS c FROM hostname.database.table
*
* Or a query with aliasing:
*
* SELECT m.member_id, m.member_name FROM members AS m
*
* Since the column name can include up to four segments (host, DB, table, column)
* or also have an alias prefix, we need to do a bit of work to figure this out and
* insert the table prefix (if it exists) in the proper position, and escape only
* the correct identifiers.
*
* @access private
* @param string
* @param bool
* @param mixed
* @param bool
* @return string
*/
上边是这个函数的注释
sql 语句有这样的写法吗？
SELECT * FROM hostname.database.table.column AS c FROM hostname.database.table
当然有那样的写法了。。。。。。 Hex 发表于 2012-2-2 11:50 static/image/common/back.gif
当然有那样的写法了。。。。。。
怎么验证这种写法的正确性呢？ 向您学习一下 xiaohua1054 发表于 2012-2-2 11:56 static/image/common/back.gif
怎么验证这种写法的正确性呢？ 向您学习一下
什么是验证正确性？SQL语法就是这样的啊。
也就是跨库跨表查询。 Hex 发表于 2012-2-2 11:57 static/image/common/back.gif
什么是验证正确性？SQL语法就是这样的啊。
也就是跨库跨表查询。
select * from database.table;
上面的sql是正确的为何我在前面加上主机名就不对了呢？
如: select * from hostname.database.table;
可以跨主机查询吗? hostname是跨主机查询时用到了吗？
xiaohua1054 发表于 2012-2-2 13:14 static/image/common/back.gif
select * from database.table;
上面的sql是正确的为何我在前面加上主机名就不对了呢？
我知道 mssql 是可以的， mysql 没试过。由于这个代码是跨数据库的，所以这么写的。
具体你可以 google 一下相关资料。
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