sql - 将单个sql列拆分为五个

Question

我试图围绕“>”定界符将一列分成最多五列，但我尝试过的东西没有成功:

我试过了

select
id, 
compoundColumn,
split(compoundColumn," > ")[1] as "first"
split(compoundColumn," > ")[2] as "second"
from table
where compoundColumn is not null

没有效果，

这有点做了(无论如何是第一部分，而不是第 n 部分)

select
id, 
compoundColumn,
first(split(compoundColumn," > ")) as "first"
nth(compoundColumn," > ")[n] as "second"
from table

我在这里找到了很多例子，但他们似乎都在说要使用括号，但括号会引发错误:

Exception: Malformed SQL. More information: Error with SQL statement: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[1] as "first" from table where compoundColumn IS NOT NULL' at line 3.

Answer 1

• 您的 SQL 中“first”后缺少逗号
• 我猜 CloudSQL 是基于某些旧版本的 MySQL，它只能使用 substring_index 进行拆分(请参阅下面的查询 - 是的，它冗长笨拙，case 子句必须清理短字符串)
• 也许尝试使用 [offset(0)] 或 [ordinal(1)] 括号，这对我们有用，尽管我们使用 Postgres 方言，也作为 # standardSql，不是#legacySql

来自第二点的 SQL:( fiddle )

select id,
  case when substring_index(cc,' > ',0) = cc then null else substring_index(substring_index(cc,' > ',1),' > ',-1) end as a1,
  case when substring_index(cc,' > ',1) = cc then null else substring_index(substring_index(cc,' > ',2),' > ',-1) end as a2,
  case when substring_index(cc,' > ',2) = cc then null else substring_index(substring_index(cc,' > ',3),' > ',-1) end as a3,
  case when substring_index(cc,' > ',3) = cc then null else substring_index(substring_index(cc,' > ',4),' > ',-1) end as a4,
  case when substring_index(cc,' > ',4) = cc then null else substring_index(substring_index(cc,' > ',5),' > ',-1) end as a5
from d