Re: Order by two columns Gaby Lopez October 31, 2014 04:26AM Re: Order by two columns Rick James October 31, 2014 08:24AM Re: Order by two columns Peter Brawley October 31, 2014 11:05AM Sorry, you can't reply to this topic. It has been closed....
If multiple rows have identical values in theORDER BYcolumns, the server is free to return those rows in any order, and may do so differently depending on the overall execution plan. In other words, the sort order of those rows is nondeterministic with respect to the nonordered columns. On...
既用于WHERE又用于ORDER BY,筛选出满足条件的数据并返回排序后的结果 举个例子,我们创建一张order_detail表 记录每一笔充值记录的userid(用户id)、money(充值金额)、create_time(充值时间),主键是自增id:CREATE TABLE `order_detail` ( `id` int(11) NOT NULL AUTO_INCREMENT, `userid` int(11) NOT NULL,...
the server is free to return those rows in any order, and may do so differently depending on the overall execution plan. In other words, the sort order of those rows is nondeterministic with respect to the nonordered columns. 如果order by的字段有多个行都有相同的值,mysql是会随机的顺序返回...
ORDER BY 排序列存在相同值时返回顺序是不固定的 If multiple rows have identical values in the ORDER BY columns, the server is free to return those rows in any order, and may do so differently depending on the overall execution plan. In other words, the sort order of those rows is nondeter...
二order by有相同,不能保证id排序 mysql文档有说明 If multiple rows have identical values in the ORDER BY columns, the server is free to return those rows in any order, and may do so differently depending on the overall execution plan. In other words, the sort order of those rows is ...
from...,如何查询表名中包含某字段的表 select * from systables where tabname like 'saa%' 此法只对Informix数据库有用查询指定数据库中指定表的所有字段名...where table_schema = ‘test’ group by table_schema; mysql中查询到包含该字段的所有表名 SELECT TABLE_NAME FROM information_schema.COLUMNS ...
If multiple rows have identical values in theORDER BYcolumns, the server is free to return those rows in any order, and may do so differently depending on the overall execution plan. In other words, the sort order of those rows is nondeterministic with respect to the nonordered columns. ...
Whether the optimizeractually does so depends on whether reading the index is more efficient than a table scanif columns not in the index must also be read. 官方文档告诉我们optimizer会帮我们选择一种高效的ORDER BY方式。 但也不能完全依赖optimizer的判断,这时合理建立索引、引导它使用指定索引可能是更...
Subject Written By Posted order by 2 columns avancha mailto November 01, 2012 09:18PM Re: order by 2 columns laptop alias November 02, 2012 01:19AM Sorry, you can't reply to this topic. It has been closed.