SUBSTRING()

Created: November-22, 2018

SUBSTRING（或等效的：SUBSTR）從指定的位置開始返回子字串，並且可選地返回指定的長度

語法：SUBSTRING(str, start_position)

SELECT SUBSTRING('foobarbaz', 4); -- 'barbaz'
SELECT SUBSTRING('foobarbaz' FROM 4); -- 'barbaz'

-- using negative indexing
SELECT SUBSTRING('foobarbaz', -6); -- 'barbaz'
SELECT SUBSTRING('foobarbaz' FROM -6); -- 'barbaz'

語法：SUBSTRING(str, start_position, length)

SELECT SUBSTRING('foobarbaz', 4, 3); -- 'bar'
SELECT SUBSTRING('foobarbaz', FROM 4 FOR 3); -- 'bar'

-- using negative indexing
SELECT SUBSTRING('foobarbaz', -6, 3); -- 'bar'
SELECT SUBSTRING('foobarbaz' FROM -6 FOR 3); -- 'bar'