手機拍照判斷相片角度

手機可以橫拍，直拍
exif資訊裡有角度可以供php判斷
參考 http://php.net/manual/en/function.exif-read-data.php

IFD0 裡的 Orientation

1: 一般照片
2: 水平翻轉
3: 180度往左轉
4: 重直翻轉
5: 重直翻轉 + 90度往右轉
6: 90度往右轉
7: 水平翻轉 + 90度往右轉
8: 90度往左轉

計算MySQL可能用到的記憶體數量

參考: http://dev.mysql.com/doc/refman/5.0/en/memory-use.html

SHOW VARIABLES LIKE 'innodb_buffer_pool_size';
SHOW VARIABLES LIKE 'innodb_additional_mem_pool_size';
SHOW VARIABLES LIKE 'innodb_log_buffer_size';
SHOW VARIABLES LIKE 'thread_stack';
SET @kilo_bytes = 1024;
SET @mega_bytes = @kilo_bytes * 1024;
SET @giga_bytes = @mega_bytes * 1024;
SET @innodb_buffer_pool_size = 2 * @giga_bytes;
SET @innodb_additional_mem_pool_size = 16 * @mega_bytes;
SET @innodb_log_buffer_size = 8 * @mega_bytes;
SET @thread_stack = 192 * @kilo_bytes;
SELECT
( @@key_buffer_size + @@query_cache_size + @@tmp_table_size
+ @innodb_buffer_pool_size + @innodb_additional_mem_pool_size
+ @innodb_log_buffer_size
+ @@max_connections * (
@@read_buffer_size + @@read_rnd_buffer_size + @@sort_buffer_size
+ @@join_buffer_size + @@binlog_cache_size + @thread_stack
) ) / @giga_bytes AS MAX_MEMORY_GB;