PostgreSQL CASE ... END有多个条件 [英] PostgreSQL CASE ... END with multiple conditions

问题描述

以下是我的表格的摘录：

Here is an extract of my table:

  gid    |    datepose    |    pvc
---------+----------------+------------
 1       |  1961          | 01
 2       |  1949          |
 3       |  1990          | 02
 1       |  1981          |
 1       |                | 03
 1       |                |

我想使用 SELECT CASE 作为波纹管：

SELECT

 gid,

 CASE
  WHEN (pvc IS NULL OR pvc = '') AND datpose < 1980) THEN '01'
  WHEN (pvc IS NULL OR pvc = '') AND datpose >= 1980) THEN '02'
  WHEN (pvc IS NULL OR pvc = '') AND (datpose IS NULL OR datpose = 0) THEN '03'
 END AS pvc

FROM my_table ;

结果与源表内容相同，什么也没有发生，并且在pg_log中没有收到错误消息文件。可能是语法错误，还是在WHEN子句中使用多个条件有问题？

The result is the same content as source table, nothing has happened and I get no error message in pg_log files. It might be a syntax error, or a problem with using multiple conditions within WHEN clauses?

感谢您的帮助和建议！

Thanks for help and advice!

推荐答案

这种代码也许应该对您有用

This kind of code perhaps should work for You

SELECT
 *,
 CASE
  WHEN (pvc IS NULL OR pvc = '') AND (datepose < 1980) THEN '01'
  WHEN (pvc IS NULL OR pvc = '') AND (datepose >= 1980) THEN '02'
  WHEN (pvc IS NULL OR pvc = '') AND (datepose IS NULL OR datepose = 0) THEN '03'
  ELSE '00'
 END AS modifiedpvc
FROM my_table;


 gid | datepose | pvc | modifiedpvc 
-----+----------+-----+-------------
   1 |     1961 | 01  | 00
   2 |     1949 |     | 01
   3 |     1990 | 02  | 00
   1 |     1981 |     | 02
   1 |          | 03  | 00
   1 |          |     | 03
(6 rows)

这篇关于PostgreSQL CASE ... END有多个条件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IT屋！