为nvarchar设置主要 [英] set primary for nvarchar

问题描述

嗨
我的用户表中有登录"字段.登录名是nvarchar(max)数据类型.
我想将此字段设置为主要".但是db不允许将nvarchar设置为primary. 如何为nvarchar字段设置主键?


致谢

Hi
I have "login" field in my Users table. login is of nvarchar(max) datatype.
I would like to set this field as Primary. but db is not allowing to set primary for nvarchar. How can I set Primary key for nvarchar fields?


Thanks and Regards

推荐答案

您无法交配.
(MAX)长度将不被接受为PK.

改用int并将nvarchar(max)用作索引.
将nvarchar用作PK会使搜索速度非常慢.

但是，如果仍然要使用nvarchar，请声明长度.这样的东西..

You cant mate.
(MAX) length wont be accepted as PK.

Use int instead and make your nvarchar(max) as index.
Using nvarchar as PK will make your searching really slow.

But if you still want to use nvarchar, declare the length. Something like this..

CREATE TABLE Login(
P_Id nvarchar(10) NOT NULL PRIMARY KEY,
password nvarchar(100) NOT NULL
)

为什么需要nvarchar(MAX)才能进行登录"?这意味着您期望2 ^ 31-1字节用于登录.
将登录"列的数据类型更改为nvarchar(20)或更实际的内容.

Why would you need nvarchar(MAX) for "login"? That means you expect 2^31-1 bytes for the login.
Change datatype for "login" column to nvarchar(20) or something more realistic.

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