我有一个名为payment_info的表，有以下记录。
paymentid | customercode | previousbalance | paymentamount | remainingbalance
-----------------------------------------------------------------------------
PID0001 | CUST024 | 10000 | 2500 | 7500
PID0002 | CUST031 | 8500 | 3500 | 5000
PID0003 | CUST005 | 12000 | 1500 | 10500
然后我想在上面的表中每行创建3行。
我希望我的结果是这样的。
Payment Group | Payment Line Item | Payment ID | Customer Code | Type | Amount
--------------------------------------------------------------------------------------------------
1 | 1 | PID0001 | CUST024 | PREVIOUS BALANCE | 10000.00
1 | 2 | | | PAYMENT AMOUNT | 2500.00
1 | 3 | | | REMAINING BALANCE | 7500.00
2 | 1 | PID0002 | CUST031 | PREVIOUS BALANCE | 8500.00
2 | 2 | | | PAYMENT AMOUNT | 3500.00
2 | 3 | | | REMAINING BALANCE | 5000.00
3 | 1 | PID0003 | CUST005 | PREVIOUS BALANCE | 12000.00
3 | 2 | | | PAYMENT AMOUNT | 1500.00
3 | 3 | | | REMAINING BALANCE | 10500.00
这是我开始的查询。但它没有返回与上述相同的结果。
select row_number() over() as id,paymentid,customercode,'PREVIOUS BALANCE' as type,previousbalance from payment_info
union
select row_number() over() as id,'','','PAYMENT AMOUNT' as type,paymentamount from payment_info
union
select row_number() over() as id,'','','REMAINING BALANCE' as type,remainingbalance from payment_info
有没有其他方法，我将不使用联合关键字？因为在真正的表中，我将使用30多列，查询数千条记录。
我也不知道如何从付款组（每个付款id）和付款行项目（每个组）创建自动生成的编号（id）。
谢谢
最佳答案
带空白的版本（空文本）unnest函数可以为您执行此操作。
如果你想要空文本，你可以用这个
SELECT ROW_NUMBER() OVER (ORDER BY paymentid) AS "group",
unnest(array[1, 2, 3]) AS "line item",
unnest(array[paymentid, '', '']) AS "paymentid",
unnest(array[customercode, '', '']) AS "customercode",
unnest(array['PREVIOUS BALANCE', 'PAYMENT AMOUNT', 'REMAINING BALANCE']) AS "type",
unnest(array[previousbalance, paymentamount, remainingbalance]) AS "amount"
FROM payment_info
ORDER BY 1, 2 ;
为了得到这个
group | line item | paymentid | customercode | type | amount
-------+-----------+-----------+--------------+-------------------+--------
1 | 1 | PID0001 | CUST024 | PREVIOUS BALANCE | 10000
1 | 2 | | | PAYMENT AMOUNT | 2500
1 | 3 | | | REMAINING BALANCE | 7500
2 | 1 | PID0002 | CUST031 | PREVIOUS BALANCE | 8500
2 | 2 | | | PAYMENT AMOUNT | 3500
2 | 3 | | | REMAINING BALANCE | 5000
3 | 1 | PID0003 | CUST005 | PREVIOUS BALANCE | 12000
3 | 2 | | | PAYMENT AMOUNT | 1500
3 | 3 | | | REMAINING BALANCE | 10500
如果您希望在空文本列中包含点或其他文本或箭头，可以使用
unnest轻松完成此操作。您可以单独控制4个空文本值。
SELECT ROW_NUMBER() OVER (ORDER BY paymentid) AS "group",
unnest(array[1, 2, 3]) AS "line item",
unnest(array[paymentid, ' a', ' c']) AS "paymentid",
unnest(array[customercode, ' b', ' d']) AS "customercode",
unnest(array['PREVIOUS BALANCE', 'PAYMENT AMOUNT', 'REMAINING BALANCE']) AS "type",
unnest(array[previousbalance, paymentamount, remainingbalance]) AS "amount"
FROM payment_info
ORDER BY 1, 2 ;
产生
group | line item | paymentid | customercode | type | amount
-------+-----------+-----------+--------------+-------------------+--------
1 | 1 | PID0001 | CUST024 | PREVIOUS BALANCE | 10000
1 | 2 | a | b | PAYMENT AMOUNT | 2500
1 | 3 | c | d | REMAINING BALANCE | 7500
2 | 1 | PID0002 | CUST031 | PREVIOUS BALANCE | 8500
2 | 2 | a | b | PAYMENT AMOUNT | 3500
2 | 3 | c | d | REMAINING BALANCE | 5000
3 | 1 | PID0003 | CUST005 | PREVIOUS BALANCE | 12000
3 | 2 | a | b | PAYMENT AMOUNT | 1500
3 | 3 | c | d | REMAINING BALANCE | 10500
你知道，这是一个非常灵活的解决方案。
关于sql - PostgreSQL-将单行更改为多行，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43840724/