Order by multiple OR 是一个用于MySQL查询语句的排序操作。它允许按照多个字段进行排序,并且使用OR逻辑进行连接。 在MySQL中,使用"Order by"关键字可以对查询结果进行排序。通常情况下,我们可以指定一个字段进行排序,例如: 代码语言:txt 复制 SELECT * FROM table_name ORDER BY column_name; 然而,在某些情况下,...
二、“order by”引发的乱序 经过一番排查,发现罪魁祸首其实是order by。当使用order by的字段存在多行相同值时,就会导致上面出现的乱序问题,这里我们来看下官方的解释[1]: ❝If multiple rows have identical values in theORDER BYcolumns, the server is free to return those rows in any order, ...
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 nondeterministic with respect to the nonordered 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. 上...
where 高于having,能写在where限定的条件就不要去having去限定了 3.5 索引的维护和优化 3.5.1 删除重复索引 注:主键约束相当于(唯一约束 + 非空约束) 一张表中最多有一个主键约束,如果设置多个主键,就会出现如下提示:Multiple primary key defined!!! 3.5.2 删除冗余索引...
I have a query that I would like to display in a specific order. Here is the query. SELECT * FROM (SELECT * FROM debtors WHERE ID LIKE + "John%" or shortName LIKE + "John%" ORDER BY shortName) as a UNION ALL SELECT * FROM (SELECT * FROM debtors WHERE ID LIKE + ("%...
Bug description When using queryRaw and MySQL, ordering by multiple columns from variables causes the query to never complete, the next line is never executed. Other queries can still be issued. Nothing is logged. The same issue occurs w...
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. ...
次优解是对order by后面的category 加索引(为什么是次优解?看完本文你将会有答案); 下面课代表将还原一下这 3 条结论的产出过程。 1. 最优解 MySQL 文档 8.2.1.19 LIMIT Query Optimization 中对此场景有如下描述: If multiple rows have identical values in the ORDER BY columns, the server is free to...
I am assuming that the tuples are physically stored by the multiple-column primary key. So why can't it jump to t.col1 = 16, and then simply grab the next 100 tuples? Instead, it is reading all tuples with t.col1 = 16 and then sorting them?!?