如何基于层级查询？

Question

我有 table，其中包含 3 个主要属性：STAGING_ID、DEVELOPMENT_ID 和 PRODUCTION_ID，每个 NUMBER_ID。我想查询一个 table 基于这个 table 说：

IF there are NO null values in any of the three columns, select STAGING_ID in 'MAIN_ID' column and 'LEVEL_DESCRIPTION' to be STAGING
IF there is a NULL value in only STAGING_ID (not DEVELOPMENT_ID or PRODUCTION_ID), then select the next level, which would be DEVELOPMENT_ID in 'MAIN_ID' column, and 'LEVEL_DESCRIPTION' to be DEVELOPMENT
IF there is a NULL value in STAGING & DEVELOPMENT (not PRODUCT_ID), then select the next level, which would be PRODUCT_ID in 'MAIN_ID' column, and 'LEVEL_DESCRIPTION' to be PRODUCTION

因此级别始终遵循此层次结构，暂存 > 开发 > 生产。

So in the picture,
FIRST ROW, should be: LEVEL_DESCRIPTION: STAGING, MAIN_ID: 3532
SECOND ROW, should be: LEVEL_DESCRIPTION: DEVELOPMENT, MAIN_ID: 3532
THIRD ROW, should be: LEVEL_DESCRIPTION: PRODUCTION, MAIN_ID: 1081

所以当我基于这个 table 查询时，我需要 3 列：

NUMBER_ID, MAIN_ID, LEVEL_DESCRIPTION

我可以做到吗？我正在考虑案例陈述，但我在制定它时遇到了问题。

DROP TABLE TBL_1;
CREATE TABLE TBL_1
(
    number_id int, 
      production_id int,
      develpoment_id int, 
    staging_id int
);

INSERT INTO TBL_1
values 
(11111,2331, 1233, 3532),
(11122,9080, 1291, null),
(11144,1082, null, null)

Answer 1

使用 COALESCE 和 CASE：

SELECT *, 
  COALESCE(staging_id, development_id, production_id, 'Not found') AS main_id,
  CASE WHEN staging_id IS NOT NULL THEN 'Staging'
       WHEN development_id IS NOT NULL THEN 'Development'
       WHEN production_id IS NOT NULL THEN 'Production'
       ELSE 'Not found'
  END AS Level_description
FROM TBL_1;

db<>fiddle demo

如何基于层级查询？

How to query based on a hierarchy level?

sql

snowflake-cloud-data-platform