如何使用 Sqlite 将逗号分隔值拆分为多行

Question

I'm using Python and SQLite to manipulate a string in android. I have a SQLite Table that looks like this:

| ID             | Country     
+----------------+-------------
| 1              | USA, Germany, Mexico 
| 2              | Brazil, Canada
| 3              | Peru

I would like to split the comma delimited values of Country column and insert them into another table countries so that Countries table looks like this

| ID             | Country     
+----------------+-------------
| 1              | USA
| 1              | Germany
| 1              | Mexico
| 2              | Brazil
| 2              | Canada
| 3              | Peru

How do I do split the values from Country column in one table and insert them into Country column of another table?

Answer 1

There is no split function in SQLite.
There is of course the substring function but it's not suitable for your needs since every row could contain more than 1 commas.
If you were an expert in SQLite I guess you could create a recursive statement using substring to split each row.
If you're not use Python to read the data, split each row and write it back to the db.

Answer 2

im solved im using python

import sqlite3
db = sqlite3.connect(':memory:')
db = sqlite3.connect('mydb.db')
cursor = db.cursor()
cursor.execute("""Select * from Countries""")
all_data = cursor.fetchall()
cursor.execute("""CREATE TABLE IF NOT EXISTS Countriess
                    (ID TEXT,
                    Country TEXT)""")
for single_data in all_data:
    countriess  = single_data[1].split(",")
    for single_country in countriess :
        cursor.execute("INSERT INTO Countriess VALUES(:id,:name)", { "id": single_data[0], "name": single_country })
db.commit()

and after use sqlite db another project; :)

Answer 3

You can use a recursive common table expression to split the comma-delimited column by extracting substrings of the Country column recursively.

CREATE TABLE country_split AS
WITH RECURSIVE split(id, value, rest) AS (
   SELECT ID, '', Country||',' FROM country
   UNION ALL SELECT
   id,
   substr(rest, 0, instr(rest, ',')),
   substr(rest, instr(rest, ',')+1)
   FROM split WHERE rest!=''
)
SELECT id, value
FROM split
WHERE value!='';