Sql 如何在别名字段上执行函数?
我在PostgreSQL中有一个视图,其中我使用COALESCE函数从表中提取第一个NOTNULL字段。i、 eSql 如何在别名字段上执行函数?,sql,postgresql,case,alias,coalesce,Sql,Postgresql,Case,Alias,Coalesce,我在PostgreSQL中有一个视图,其中我使用COALESCE函数从表中提取第一个NOTNULL字段。i、 e SELECT SRC.SAP_SETNODE.SUBSET_CLS, COALESCE( SETNODE_13.SUBSET_NAME, SETNODE_12.SUBSET_NAME, SETNODE_11.SUBSET_NAME, SETNODE_10.SUBSET_NAME, SETNODE_9.SUBSET_NAME, SET
SELECT
SRC.SAP_SETNODE.SUBSET_CLS,
COALESCE(
SETNODE_13.SUBSET_NAME,
SETNODE_12.SUBSET_NAME,
SETNODE_11.SUBSET_NAME,
SETNODE_10.SUBSET_NAME,
SETNODE_9.SUBSET_NAME,
SETNODE_8.SUBSET_NAME,
SETNODE_7.SUBSET_NAME,
SETNODE_6.SUBSET_NAME,
SETNODE_5.SUBSET_NAME,
SETNODE_4.SUBSET_NAME,
SETNODE_3.SUBSET_NAME,
SETNODE_2.SUBSET_NAME,
SETNODE_1.SUBSET_NAME,
SRC.SAP_SETNODE.SUBSET_NAME,
SRC.SAP_SETNODE.SET_NAME)
AS prctr1,
有了这个字段后,我想创建一个名为prctr2的新字段,如果prctr1字段类似于“PC%”,我想在该字段上执行拆分部分和覆盖功能
我试图就这一点做一个案例陈述,大致如下:
WHEN prctr1 LIKE 'PC%' THEN split_part( overlay(prctr1 placing '00000' from 1 for 2 ),'.',1)
ELSE prctr1
但我收到一条消息说prctr1列不存在。有什么方法可以实现这一点吗?只需将主查询封装在外部查询中,然后执行CASE语句,如下所示:
SELECT CASE WHEN prctr1 LIKE 'PC%' THEN split_part( overlay(prctr1 placing '00000' from 1 for 2 ),'.',1)
ELSE prctr1 end as pctrl1
FROM (
SELECT
SRC.SAP_SETNODE.SUBSET_CLS,
COALESCE(
SETNODE_13.SUBSET_NAME,
SETNODE_12.SUBSET_NAME,
SETNODE_11.SUBSET_NAME,
SETNODE_10.SUBSET_NAME,
SETNODE_9.SUBSET_NAME,
SETNODE_8.SUBSET_NAME,
SETNODE_7.SUBSET_NAME,
SETNODE_6.SUBSET_NAME,
SETNODE_5.SUBSET_NAME,
SETNODE_4.SUBSET_NAME,
SETNODE_3.SUBSET_NAME,
SETNODE_2.SUBSET_NAME,
SETNODE_1.SUBSET_NAME,
SRC.SAP_SETNODE.SUBSET_NAME,
SRC.SAP_SETNODE.SET_NAME)
AS prctr1
) as foo