mysql functions实例：使用LOAD_FILE返回文件大小

分享一个mysql函数的例子，学习load_file的用法。

代码：

mysql> delimiter $$
mysql> CREATE PROCEDURE filesize(in_file_name VARCHAR(128))
    ->
    -> BEGIN
    ->   DECLARE mytext TEXT;
    ->   SET mytext=LOAD_FILE(in_file_name);
    ->   SELECT in_file_name||' contains '||length(mytext)||' bytes'
    ->       AS output;
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql> call filesize("a.txt");
+--------+
| output |
+--------+
|   NULL |
+--------+
1 row in set (0.00 sec)

Query OK, 0 rows affected, 2 warnings (0.00 sec)

mysql> drop procedure filesize;
Query OK, 0 rows affected (0.00 sec)