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'{value1,value2,value3}'

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ARRAY['value1','value2','value3']

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SELECT field1::VARCHAR
FROM UNNEST(ARRAY['value1','value2','value3']) AS field1;

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db=# SELECT field1::VARCHAR
db-# FROM UNNEST(ARRAY['value1','value2','value3']) AS field1;

 field1
--------
 value1
 value2
 value3
(3 rows)

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SELECT field1::VARCHAR, test_function(field1::VARCHAR) AS result
FROM UNNEST(ARRAY['value1','value2','value3']) AS field1;

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ARRAY['{100,value1,2018/10/01}','{200,value2,2018/10/02}']

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SELECT (fields::VARCHAR[])[1]::NUMERIC AS field1
     , (fields::VARCHAR[])[2]::VARCHAR AS field2
     , (fields::VARCHAR[])[3]::DATE AS field3
FROM UNNEST(ARRAY['{100,value1,2018/10/01}'
                 ,'{200,value2,2018/10/02}']) AS fields;

�|�C���g�� "fields" �ɔz��̕������`������̂� ����� "VARCHAR[]" �ŃL���X�g���܂��B

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db=# SELECT (fields::VARCHAR[])[1]::NUMERIC AS field1
db-#      , (fields::VARCHAR[])[2]::VARCHAR AS field2
db-#      , (fields::VARCHAR[])[3]::DATE AS field3
db-# FROM UNNEST(ARRAY['{100,value1,2018/10/01}'
db-#                  ,'{200,value2,2018/10/02}']) AS fields;

 field1 | field2 |   field3
--------+--------+------------
    100 | value1 | 2018-10-01
    200 | value2 | 2018-10-02
(2 rows)

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ARRAY['{100,val\,ue1,2018/10/01}','{200,value2,2018/10/02}']