最近在做自己的网站,有些地方要判断mysql语句是否执行成功了,或者是SELECT语句是否取到了结果,查了查资料,终于解决了。
先来看一段php代码,有点长,建议直接运行一遍:点击下载代码
define("HOST","database ip"); define("USER","your database account"); define("PASS","your password"); define("DB","database name"); $con = mysql_connect(HOST,USER,PASS); if (!$con) die('Could not connect: ' . mysql_error()); mysql_select_db(DB, $con); //sql 0 $sql = "DROP TABLE `test` "; $result=mysql_query($sql); if($result)echo "table `test` already exist, so I drop it to continue the test "; echo " "; //sql 1 $sql="CREATE TABLE `test` ( `rid` int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (`rid`), `uid` int(11) NOT NULL UNIQUE, `face` int NOT NULL, `nick` varchar(12) NOT NULL, `luck` int NOT NULL DEFAULT 10 ) ENGINE=MyISAM DEFAULT CHARSET=utf8;"; $result=mysql_query($sql,$con); if($result)echo "sql 1:",$sql," executed successfully "; else echo "sql 1:",$sql,"fail "; echo " "; //sql 2 $sql="INSERT INTO `test`(`uid`, `face`, `nick`) VALUES ('1','1','newnius')"; $result=mysql_query($sql); $count=mysql_affected_rows(); if($count>0)echo "sql 2:",$sql," executed successfully "; else echo "sql 2:",$sql,"fail "; echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //sql 3 $sql="INSERT INTO `test`(`uid`, `face`) VALUES ('1','1')"; $result=mysql_query($sql); $count=mysql_affected_rows(); if($count>0)echo "sql 3:",$sql," executed successfully "; else echo "sql 3:",$sql,"fail,","because face can not be null "; echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //add 3 records echo "add 3 records "; $sql="INSERT INTO `test`(`uid`, `face`, `nick`) VALUES ('2','1','order')"; $result=mysql_query($sql); $sql="INSERT INTO `test`(`uid`, `face`, `nick`) VALUES ('3','2','order')"; $result=mysql_query($sql); $sql="INSERT INTO `test`(`uid`, `face`, `nick`) VALUES ('4','3','order')"; $result=mysql_query($sql); echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //sql 4 $sql="SELECT * FROM `test` WHERE nick='newnius' LIMIT 1"; $result = mysql_query($sql); $count=mysql_num_rows($result); if($count){ echo "sql 4:",$sql," executed successfully. "; echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; } else echo "sql 4:",$sql,"fail "; echo " "; //sql 5 $sql="UPDATE `test` SET uid = '10086' WHERE nick='newnius'"; $result = mysql_query($sql); $count=mysql_affected_rows(); if($count>0) { echo "sql 5:",$sql," executed successfully "; echo $count," record(s) is(are) affected "; } else echo "sql 5:",$sql,"fail "; echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //sql 6 $sql="UPDATE `test` SET uid = '10086' WHERE nick='unknown'"; $result = mysql_query($sql); $count=mysql_affected_rows(); if($count>0)echo "sql 6:",$sql," executed successfully "; else echo "sql 6:",$sql,"fail, because no record found "; echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //sql 7 $sql="DELETE FROM `test` WHERE nick ='order'"; $result = mysql_query($sql); $count=mysql_affected_rows(); if($count>0) { echo "sql 7:",$sql," executed successfully "; echo $count," record(s) deleted "; } else echo "sql 7:",$sql,"fail "; echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //sql 8 $sql="DELETE FROM `test` WHERE nick ='order'"; $result = mysql_query($sql); $count=mysql_affected_rows(); if($count>0)echo "sql 8:",$sql," executed successfully "; else echo "sql 8:",$sql,"fail, because no record found "; echo " "; //list records echo "list records "; $sql="SELECT * FROM `test` "; $result = mysql_query($sql); $count=mysql_num_rows($result); echo $count," record(s) found: "; while($row = mysql_fetch_array($result))echo "rid:",$row["rid"]," uid:",$row["uid"]," nick:",$row["nick"]," "; echo " "; //sql 9 $sql = "DROP TABLE `test` "; $result=mysql_query($sql); if($result)echo "sql 9:",$sql," executed successfully "; else echo "sql 9:",$sql,"fail "; echo " "; mysql_close($con); echo "test finished, thank you! 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从代码中可以看出,判断INSERT、UPDATE、DELETE 用的判断方法是mysql_affected_rows() ,该方法返回的是最近一次与 link_identifier 关联的 INSERT、UPDATE 或 DELETE 查询所影响的记录行数。关于mysql_affected_rows()的返回值,w3school是如此说明的:
1、执行成功,则返回受影响的行的数目,如果最近一次查询失败的话,函数返回 -1。
2、如果最近一次操作是没有任何条件(WHERE)的 DELETE 查询,在表中所有的记录都会被删除,但本函数返回值在 4.1.2 版之前都为 0。
3、当使用 UPDATE 查询,MySQL 不会将原值与新值一样的列更新。这样使得 mysql_affected_rows() 函数返回值不一定就是查询条件所符合的记录数,只有真正被修改的记录数才会被返回。
4、REPLACE 语句首先删除具有相同主键的记录,然后插入一个新记录。该函数返回的是被删除的记录数加上被插入的记录数。
显然,INSERT、UPDATE 或 DELETE都(可能,指UPDATE)会改变数据表,所以可以用该函数。然而SELECT语句不会对数据表进行改动,故该函数不能用来判断SELECT的执行情况。
不过既然SELECT语句是为了取出符合条件的结果,我们就可以对结果进行分析,用mysql_num_rows($result) 这个函数得到结果的记录数。
由此可见,两个函数就可以基本解决我们的问题啦。
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