show table status from database.table

执行的行数居然是个可变的值，官方文档解释
The number of rows. Some storage engines, such as MyISAM, store the exact count. 
For other storage engines, such as InnoDB, this value is an approximation, and may vary from the actual value by as much as 40 to 50%. 
In such cases, use SELECT COUNT(*) to obtain an accurate count.
so，用select count(*) from table  较为准确点