PostgreSQL数据过滤(一)

官网地址

声明: 由于操作系统, 版本更新等原因, 文章所列内容不一定100%复现, 还要以官方信息为准

https://www.postgresql.org/

PostgreSQL概述

PostgreSQL: 世界上最先进的开源关系数据库。

PostgreSQL的where子命令介绍

• 筛选返回的行

  SELECT select_list 
  FROM table_name 
  WHERE condition 
  ORDER BY sort_expression;
  

• 执行顺序

  • from -> where -> select -> order by

PostgreSQL的where子命令实操

数据库样例数据来源: https://blog.csdn.net/zwq56693/article/details/137473602

• 相等的操作

  SELECT last_name, first_name 
  FROM customer 
  WHERE first_name = 'Jamie';
  

• and进行逻辑操作, 满足多个过滤条件

  SELECT last_name, first_name 
  FROM customer 
  WHERE first_name = 'Jamie' AND last_name = 'Rice';
  

• or逻辑操作, 满足其中的部分条件即可

  SELECT first_name, last_name 
  FROM customer 
  WHERE last_name = 'Rodriguez' OR first_name = 'Adam';
  

• in满足条件一系列的值

  SELECT first_name, last_name 
  FROM customer 
  WHERE first_name IN ('Ann', 'Anne', 'Annie');
  

• like加上通配符就是模糊查询, 不然就是等于

  SELECT first_name, last_name 
  FROM customer 
  WHERE first_name LIKE 'Ann%';
  

• between 大于等于小的值, 小于等于大的值

  SELECT first_name, LENGTH(first_name) name_length 
  FROM customer 
  WHERE first_name LIKE 'A%' AND LENGTH(first_name) BETWEEN 3 AND 5 
  ORDER BY name_length;
  

• <>不等于或者!=

  SELECT first_name, last_name 
  FROM customer 
  WHERE first_name LIKE 'Bra%' AND last_name <> 'Motley';
  

更新计划

欲知后事如何, 请听下回分解