I have a GROUP_CONCAT:
我有一个GROUP_CONCAT:
GROUP_CONCAT(CASE WHEN c.twitter IS NOT NULL AND
c.twitter <> '' THEN CONCAT('!',c.twitter) END SEPARATOR ' ') AS tweetWinners
This works great when the user has a twitter name in the database. I then store this like so:
当用户在数据库中有一个twitter名称时，这种方法非常有效。然后我这样存储:
$tweeters = $row['tweetWinners'];
Which gives me a list like:
这给了我一个列表:
@twitteruser1 @twitteruser2 @twitteruser3
However, I want to display two different options:
然而，我想展示两种不同的选择:
if ($tweeters == '') {
echo "Something";
} else {
echo "$tweeters";
}
But it always jumps to the else even if there aren't any twitter users.
但即使没有twitter用户，它也总是跳到别的地方。
Any help would be appreciated so that I know
我知道，任何帮助都是值得感激的。
1 个解决方案
#1
2
GROUP_CONCAT() returns NULL if there are no non-NULL-Values. see http://dev.mysql.com/doc/refman/5.5/en/group-by-functions.html#function_group-concat
如果没有非空值，GROUP_CONCAT()将返回NULL。看到http://dev.mysql.com/doc/refman/5.5/en/group-by-functions.html function_group-concat
NULL is not an empty string. COALESCE might help. http://dev.mysql.com/doc/refman/5.5/en/comparison-operators.html#function_coalesce
NULL不是空字符串。合并可能会有所帮助。http://dev.mysql.com/doc/refman/5.5/en/comparison-operators.html function_coalesce
#1
2
GROUP_CONCAT() returns NULL if there are no non-NULL-Values. see http://dev.mysql.com/doc/refman/5.5/en/group-by-functions.html#function_group-concat
如果没有非空值，GROUP_CONCAT()将返回NULL。看到http://dev.mysql.com/doc/refman/5.5/en/group-by-functions.html function_group-concat
NULL is not an empty string. COALESCE might help. http://dev.mysql.com/doc/refman/5.5/en/comparison-operators.html#function_coalesce
NULL不是空字符串。合并可能会有所帮助。http://dev.mysql.com/doc/refman/5.5/en/comparison-operators.html function_coalesce