mysql join
一般说join时 小表放左边,大表放右边。就是小表作为驱动表。
网上找到了另一种说法:对于nested loops join和hash join来说,小的结果集先访问,大的结果集后访问(即与表的大小没有关系,与具体sql返回的结果集大小有关);而对于merge sort j[……]
1.看手册
The DATE
type is used for values with a date part but no time part. MySQL retrieves and displays DATE
values in 'YYYY-MM-DD'
format. The supp[……]
For example, suppose you have a table with 200K rows and you need only 100 random rows from the table. The fragment of the result set from the total r[……]