PostgreSQL主键自动增量在C ++中崩溃 [英] PostgreSQL primary key auto increment crashes in C++

问题描述

使用C ++在PostgreSQL中创建整数主键自动增量字段的正确语法是什么？

我以

开头

  db-> ExecuteSQL（CREATE TABLE mytable（\mytableid\INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL，
  
 
 
 
这会进行编译，但进程崩溃，不会创建任何字段。
  db-> ExecuteSQL（CREATE TABLE mytable（\mytableid\serial PRIMARY KEY NOT NULL，
  
这样可以正确地创建字段。
 
 
 
我需要 NOT NULL 或者这不是必需的 serial ？
 
这是Postgres中创建主键字段最好的语法和方法吗？
解决方案
你不需要 NOT NULL  =http://www.postgresql.org/docs/current/interactive/ddl-constraints.html =nofollow>  PRIMARY KEYS  。根据文档：
 
 
技术上，主键约束仅仅是
唯一约束和非空约束的组合。 
 
 
此外，  serial 也意味着NOT NULL 。它不是数据类型本身，只是一个符号方便的整数NOT NULL 与附加的序列。
 
 
 
这是完美的语法：
  CREATE TABLE mytable（mytableid serial PRIMARY KEY）; 
  
您不需要双引号列名称，只要您不想使用混合案例标识符，保留字或非法字符。我建议使用法律，小写标识符专门使你的代码不容易出错（和你的生活更简单）。
 
What is the correct syntax to create an integer primary key auto incremental field in PostgreSQL using C++?

I started with 
db->ExecuteSQL("CREATE TABLE mytable (\"mytableid\" INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL,
This compiles but the process crashes and no field is created.
db->ExecuteSQL("CREATE TABLE mytable (\"mytableid\" serial PRIMARY KEY NOT NULL,
This works and does create the field correctly.

Do I need the NOT NULL or is this not necessary with serial?

Is this the best syntax and method in Postgres for primary key field creation?
解决方案
You do not need the NOT NULL. It is implied when you define the column PRIMARY KEYS. Per documentation:

  
Technically, a primary key constraint is simply a combination of a
  unique constraint and a not-null constraint.
In addition, serial also implies NOT NULL. It's not a data type per se, just a notational convenience for integer NOT NULL with an attached sequence.

So this is perfect syntax:
CREATE TABLE mytable (mytableid serial PRIMARY KEY);
You don't need to double quote the column name as long as you don't want to use mixed case identifiers, reserved words or "illegal" characters. I would advise to use legal, lower case identifiers exclusively to make your code less error-prone (and your life simpler).

                        
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