PostgreSQL: Frequency Table Expansion
-
30-06-2021 - |
题
Does anyone know how to expand a frequency table in PostgreSQL?
For example, transform table x:
data | frequency
-------+-----------
string | 4
into
data | index
-------+-------
string | 1
string | 2
string | 3
string | 4
Set up code:
CREATE TABLE x (
data TEXT,
frequency INTEGER
);
INSERT INTO x VALUES ('string',4);
解决方案
This is amazingly simple with generate_series()
:
SELECT data, generate_series(1, frequency) AS index
FROM x;
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