[英]Extract value from table in new column with SQL query
我在數據庫中有一個帶有文本列的表,其中每一行的記錄都記錄為列表,例如列test
:
[['a','1'],['b','2'],['c','3']]
[['a','2'],['a','4'],['c','8'],['d','3']
[['b','3'],['c',5'],['c','6'],['d','4']]
我想將值提取到三個新列xyz
中
像這樣:
x y z
['a','1'],['b','2'] ['c','3']
['a','2'],['a','4'] ['c','8'] ['d','3']
['b','3'] ['c','5'],['c','6'] ['d','4']
是否可以使用 SQL 語句來做到這一點?
提前致謝
您需要遞歸 CTE 來拆分每一行,然后 GROUP_CONCAT() 根據您的要求收集值:
WITH cte AS (
SELECT rowid,
SUBSTR(test, 1, INSTR(test || ';', ';') - 1) col,
SUBSTR(test, INSTR(test || ';', ';') + 1) rest
FROM (SELECT rowid, REPLACE(REPLACE(REPLACE(test, '[[', '['), ']]', ']'), '],[', '];[') test FROM tablename)
UNION ALL
SELECT rowid,
SUBSTR(rest, 1, INSTR(rest || ';', ';') - 1),
SUBSTR(rest, INSTR(rest || ';', ';') + 1)
FROM cte
WHERE LENGTH(rest) > 0
)
SELECT GROUP_CONCAT(CASE WHEN col LIKE '[''a'',%' OR col LIKE '[''b'',%' THEN col END) x,
GROUP_CONCAT(CASE WHEN col LIKE '[''c'',%' THEN col END) y,
GROUP_CONCAT(CASE WHEN col LIKE '[''d'',%' THEN col END) z
FROM cte
GROUP BY rowid
請參閱演示。
結果:
X | 是的 | z |
---|---|---|
['a','1'],['b','2'] | ['c','3'] | null |
['a','2'],['a','4'] | ['c','8'] | ['d','3'] |
['b','3'] | ['c',5'],['c','6'] | ['d','4'] |
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