SQLite 将单行转换为多行

Question

SQLite
我想将由 ',' 分隔的单行值转换为多行

示例：

Single_Row

6,7,8,9,10,11,12,13,14,15,16

结果必须是：

多行

我试着用 substr 函数来做，但得到了意想不到的结果

select 
 numbers.n,
substr(CbahiHSSpecialtyUnits.units,numbers.n,1) 
from
  numbers inner join CbahiHSSpecialtyUnits
  on  LENGTH(CbahiHSSpecialtyUnits.units)
     - LENGTH(REPLACE(CbahiHSSpecialtyUnits.units, ',', ''))>=numbers.n-1
  WHERE HsSubStandardID=22 and SpecialtyID=2 and  numbers.n>0
  order by numbers.n;

一件好事是我的行数是正确的..但是应该分开的值是错误的.. 请注意数字 table 是我在这个 post 的帮助下为索引目的创建的。 SQL split values to multiple rows

Answer 1

你可以用递归 CTE:

WITH cte AS (
  SELECT SUBSTR(Units, 1, INSTR(Units || ',', ',') - 1) col,
         SUBSTR(Units, INSTR(Units || ',', ',') + 1) value
  FROM CbahiHSSpecialtyUnits
  WHERE HsSubStandardID=22 AND SpecialtyID = 2
  UNION ALL
  SELECT SUBSTR(value, 1, INSTR(value || ',', ',') - 1),
         SUBSTR(value, INSTR(value || ',', ',') + 1)
  FROM cte
  WHERE LENGTH(value) > 0
)
SELECT col 
FROM cte
WHERE col + 0 > 0

或者，如果你知道数字的上限是，说20并且数字之间没有重复：

WITH cte AS (SELECT 1 col UNION ALL SELECT col + 1 FROM cte WHERE col < 20)
SELECT c.col 
FROM cte c INNER JOIN CbahiHSSpecialtyUnits u
ON ',' || u.Units || ',' LIKE '%,' || c.col || ',%'
WHERE HsSubStandardID=22 AND SpecialtyID = 2

参见demo。
结果：

col
6
7
8
9
10
11
12
13
14
15
16

Answer 2

我得到了解决方案

http://www.samuelbosch.com/2018/02/split-into-rows-sqlite.html

WITH RECURSIVE split(predictorset_id, predictor_name, rest) AS (
  SELECT CbahiHSSpecialtyUnits.SpclUnitSerial, '', units || ',' FROM CbahiHSSpecialtyUnits WHERE HsSubStandardID=22 and SpecialtyID=2 
   UNION ALL
  SELECT predictorset_id, 
         substr(rest, 0, instr(rest, ',')),
         substr(rest, instr(rest, ',')+1)
    FROM split
   WHERE rest <> ''

SQLite 将单行转换为多行

SQLite convert single row to multiple rows

sqlite

android-sqlite

示例：

Single_Row

结果必须是：

多行