postgresql - 重复一列，将其复制到同一行中更多相同的列

Question

我有一个包含 3 列的表格:(ID, city,city_pop)。 我只想复制 city_pop 列 20 次。因此最终表将如下所示:(ID, city, city_pop, city_pop1, city_pop2, ...city_pop20) 具有与 city_pop 相同的值。可能吗？

Answer 1

-- CREATE TABLE cities20 AS
SELECT id,city
    , city_pop AS city_pop0
    , city_pop AS city_pop1
    , city_pop AS city_pop2
    , city_pop AS city_pop3
    , city_pop AS city_pop4
    , city_pop AS city_pop5
    , city_pop AS city_pop6
    , city_pop AS city_pop7
    , city_pop AS city_pop8
    , city_pop AS city_pop9
    , city_pop AS city_pop10
    , city_pop AS city_pop11
    , city_pop AS city_pop12
    , city_pop AS city_pop13
    , city_pop AS city_pop14
    , city_pop AS city_pop15
    , city_pop AS city_pop16
    , city_pop AS city_pop17
    , city_pop AS city_pop18
    , city_pop AS city_pop19
 FROM cities
     ;