PostgreSQL - Increment(自增)

AUTO INCREMENT(自动增长) 会在新记录插入表中时生成一个唯一的数字，PostgreSQL 使用序列来标识字段的自增长，数据类型有 smallserial、serial 和 bigserial 。

Auto Increment - 语法

SERIAL 数据类型的基本用法如下-

CREATE TABLE tablename (
   colname SERIAL
);

Auto Increment - 示例

考虑如下创建的COMPANY表-

无涯教程网

testdb=# CREATE TABLE COMPANY(
   ID  SERIAL PRIMARY KEY,
   NAME           TEXT      NOT NULL,
   AGE            INT       NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);

现在，将以下记录插入表COMPANY-

INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ( 'Paul', 32, 'California', 20000.00 );

INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ('Learnfk', 25, 'Texas', 15000.00 );

INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ('Teddy', 23, 'Norway', 20000.00 );

INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ( 'Mark', 25, 'Rich-Mond ', 65000.00 );

INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ( 'David', 27, 'Texas', 85000.00 );


INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ( 'Kim', 22, 'South-Hall', 45000.00 );

INSERT INTO COMPANY (NAME,AGE,ADDRESS,SALARY)
VALUES ( 'James', 24, 'Houston', 10000.00 );

这将在表COMPANY中插入7个元组，并且COMPANY将具有以下记录-

链接：https://www.learnfk.comhttps://www.learnfk.com/postgresql/postgresql-using-autoincrement.html

来源：LearnFk无涯教程网

 id | name  | age | address    | salary
----+-------+-----+------------+--------
  1 | Paul  |  32 | California |  20000
  2 | Learnfk |  25 | Texas      |  15000
  3 | Teddy |  23 | Norway     |  20000
  4 | Mark  |  25 | Rich-Mond  |  65000
  5 | David |  27 | Texas      |  85000
  6 | Kim   |  22 | South-Hall |  45000
  7 | James |  24 | Houston    |  10000