Is there a way to create a set from a string of separated values in MySQL? For example:
'the,quick,brown,fox' 开发者_如何学运维=> 'the','quick','brown','fox'
A sort of inverse EXPORT_SET without the bit fiddeling.
Regards
If you're trying to use the set in an IN
statement, instead of splitting the string, you could do a comparison like:
SELECT * FROM `table` WHERE 'the,quick,brown,fox' REGEXP CONCAT('(^|,)','word','(,|$)');
I'm not sure how efficient this would be if your dataset is large, but it might be faster than reading into and selecting from a temporary table.
Tested on MySQL 5.1.41:
DROP TABLE IF EXISTS n;
CREATE TEMPORARY TABLE n AS
SELECT -1 AS N UNION
SELECT -2 UNION
SELECT -3 UNION
SELECT -4 UNION
SELECT -5;
DROP TABLE IF EXISTS foo;
CREATE TABLE foo AS
SELECT 'the,quick,brown,fox' AS csv;
SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(foo.csv, ',', n.n), ',', 1) AS word
FROM foo JOIN n
ON (LENGTH(REPLACE(foo.csv, ',', ''))-LENGTH(foo.csv) <= n.n+1);
Result:
+-------+
| word |
+-------+
| fox |
| brown |
| quick |
| the |
+-------+
You could split the text into separate elements, read into a temp table, and then select the result.
e.g.
http://forums.mysql.com/read.php?60,78776,242420#msg-242420
Wouldn't FIND_IN_SET solve your problem ?
FIND_IN_SET()
精彩评论