今天，当我编写一个复杂的查询时，偶然地发现，即使在查询中设置了LIMIT，MySQL服务器也返回了COUNT的总行数。
示例：
SELECT COUNT(*) FROM `log` LIMIT 10;
输出：
5219
但是，如果我在没有COUNT的情况下运行查询，它将仅返回10行。我的问题是，
当
LIMIT存在时，为什么MySQL会忽略COUNT？
答案 0 :(得分：1)
LIMIT用于返回总结果的子集，在您的情况下，结果仅一行，因此没有效果
答案 1 :(得分：0)
def partition(input :List[Int] // a sorted List of Ints
,prev :Int // Int previously added to the accumulator
,splits :List[List[Int]] // accumulator of Ints for eventual output
): List[List[Int]] = { // the output (same type as accumulator)
input match { // what does input look like?
case Nil => splits // input is empty, return the accumulator
// input has a head and tail, head is close to previous Int
case h :: t if h-prev < 2 =>
// start again with new input (current tail), new previous (current head),
// and the current head inserted into accumulator
partition(t, h, (h :: splits.head) :: splits.tail)
// input has a head and tail, head is not close to previous Int
case h :: t =>
// start again with new input (current tail), new previous (current head),
// and the current head is the start of a new sub-list in the accumulator
partition(t, h, List(h) :: splits)
}
}
子句用于选择数量有限的记录的目的，而LIMIT是聚合函数，它将返回聚合结果。一起使用count和LIMIT毫无意义，因为COUNT可能会返回任意n条记录。