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    2. 一级索引和二级索引到底有什么区别?

      What is difference between primary index and secondary index exactly?(一级索引和二级索引到底有什么区别?)

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              1. 本文介绍了一级索引和二级索引到底有什么区别?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!

                问题描述

                谁能告诉我主索引和主索引之间的确切区别是什么?二级指标?属于主要类别的不同索引是什么?二级索引?以及使用主索引相对于二级索引的优势是什么?反之亦然?

                Can any one tell me what's the exact difference between Primary index & Secondary index? What are the different indexes that comes under category of primary & secondary index? And what's advantages of using primary index over secondary index & vice versa?

                推荐答案

                主索引:

                主索引是一组字段的索引,包括字段的唯一主键,并保证不包含重复项.也称为聚集索引.例如.员工 ID 可以是它的示例.

                A primary index is an index on a set of fields that includes the unique primary key for the field and is guaranteed not to contain duplicates. Also Called a Clustered index. eg. Employee ID can be Example of it.

                二级索引:

                二级索引是一个非主索引并且可能有重复的索引.例如.员工姓名就是一个例子.因为员工姓名可以有相似的值.

                A Secondary index is an index that is not a primary index and may have duplicates. eg. Employee name can be example of it. Because Employee name can have similar values.

                主索引包含表的关键字段.当表被激活时,主索引会自动在数据库中创建.如果一个大表被频繁访问以至于无法应用主索引排序,你应该为该表创建二级索引.

                The primary index contains the key fields of the table. The primary index is automatically created in the database when the table is activated. If a large table is frequently accessed such that it is not possible to apply primary index sorting, you should create secondary indexes for the table.

                表上的索引具有三个字符的索引 ID.'0' 为主索引保留.客户可以在 SAP 表上创建自己的索引;他们的 ID 必须以 Y 或 Z 开头.

                The indexes on a table have a three-character index ID. '0' is reserved for the primary index. Customers can create their own indexes on SAP tables; their IDs must begin with Y or Z.

                这篇关于一级索引和二级索引到底有什么区别?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!

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