如果找不到匹配项，返回的结果是什么 [英] What is this returning if a match isn't found

问题描述

如果找不到匹配项，这是否返回零?如果没有，那我该怎么办?

Is this returning a zero if a match isn''t found? If not then how would I do that?

sprintf(queryString, "SELECT COUNT(*) FROM tblURLIP WHERE IP = '%s' AND IPStatus = '1' AND IPMax = '0' AND  IPType = 3", ipSrc);

推荐答案

如果选择count(*)会导致0行，因为where子句不会导致结果，您将获得0作为答案.

IF the Select count(*) results in 0 rows because the where clause does not lead to results, you will get 0 as answer.

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