这个语句非常好，

例如：

IF(SELECT * FROM test.relation_seo_keyword_webpage WHERE keywordid = 1 AND webpageid =1) {
   UPDATE test.relation_seo_keyword_webpage SET positionCount= positionCount+1,searchCount = searchCount +1 WHERE keywordid = 1 AND webpageid =1; } ELSE {
   INSERT INTO test.relation_seo_keyword_webpage(keywordid,webpageid,positionCount,searchCount) VALUES (1,1,1,1); }

三条SQL，现在如果用INSERT ... ON DUPLICTE KEY UPDATE来实现就方便多了

INSERT INTO test.relation_seo_keyword_webpage VALUES(1,1,1,1) ON DUPLICATE KEY UPDATE keywordid=1,webpageid=1,positionCount= positionCount+1,searchCount = searchCount +1;

最好是指定列名

INSERT INTO test.relation_seo_keyword_webpage(keywordid,webpageid,positionCount,searchCount) VALUES(1,1,1,1) ON DUPLICATE KEY UPDATE keywordid=1,webpageid=1,positionCount= positionCount+1,searchCount = searchCount +1;

注意，如果表中keywordid和webpageid在表中不是主键（组合主键），如果执行以上语句就会插入重复数据，所以需要主键。

修改表的主键语句：

ALTER TABLE test.relation_seo_keyword_webpage ADD(CONSTRAINT PRIMARY KEY(keywordid,webpageid));

注意我的mysql版本是：5.0.51b

建表语句：

-- -- Table structure for table `relation_seo_keyword_webpage` -- DROP TABLE IF EXISTS `relation_seo_keyword_webpage`; SET @saved_cs_client     = @@character_set_client; SET character_set_client = utf8; CREATE TABLE `relation_seo_keyword_webpage` (   `keywordid` int(11) NOT NULL,   `webpageid` int(11) NOT NULL,   `positionCount` int(10) unsigned zerofill default '0000000000',   `searchCount` int(10) unsigned zerofill default '0000000000', PRIMARY KEY  (`keywordid`,`webpageid`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; SET character_set_client = @saved_cs_client; -- -- Dumping data for table `relation_seo_keyword_webpage` --