您可以将它们分成几个组成部分,例如:
SELECT REPLACE(SUBSTRING(SUBSTRING_INDEX(prog_id, '.', 1),
LENGTH(SUBSTRING_INDEX(prog_id, '.', 1 -1)) + 1),
'.', '') AS id1,
REPLACE(SUBSTRING(SUBSTRING_INDEX(prog_id, '.', 2),
LENGTH(SUBSTRING_INDEX(prog_id, '.', 2 -1)) + 1),
'.', '') AS id2,
REPLACE(SUBSTRING(SUBSTRING_INDEX(prog_id, '.', 3),
LENGTH(SUBSTRING_INDEX(prog_id, '.', 3 -1)) + 1),
'.', '') AS id3
FROM programs
ORDER BY CAST(id1 AS INT(4)), CAST(id2 AS INT(4)), CAST(id3 AS INT(4))
最好的方法是创建像 yoda2k 所说的额外字段,但如果您没有该访问权限,那么您可以使用上面的方法。
您可以将其封装到一个函数中,例如:
CREATE FUNCTION SPLIT_STR(
x VARCHAR(255),
delim VARCHAR(12),
pos INT
)
RETURNS VARCHAR(255)
RETURN REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos),
LENGTH(SUBSTRING_INDEX(x, delim, pos -1)) + 1),
delim, '');
Then do:
SELECT SPLIT_STR(prog_id, '.', 1) AS id1,
SPLIT_STR(prog_id, '.', 2) AS id2,
SPLIT_STR(prog_id, '.', 3) AS id3,
FROM programs
ORDER BY CAST(id1 AS INT(4)), CAST(id2 AS INT(4)), CAST(id3 AS INT(4))