(My front-end, php novice)
Excuse me, after getting the front-end data, why do you have to write it when inserting it into the database
<code>if ($conn -> query($sql) == true){echo"插入数据库成功"}</code>
In this sentence, inserting data can be successful. Isn’t this a judgment? If you don’t judge, just insert the data
<code>$sql = "insert into yihe (name, psw) values ('$name', '$psw')";</code>
Isn’t it possible to insert it directly into the database????
Reply content:
(My front-end, php novice)
Excuse me, after getting the front-end data, why do you have to write it when inserting it into the database
<code>if ($conn -> query($sql) == true){echo"插入数据库成功"}</code>
In this sentence, inserting data can be successful. Isn’t this a judgment? If you don’t judge, just insert the data
<code>$sql = "insert into yihe (name, psw) values ('$name', '$psw')";</code>
Isn’t it possible to insert it directly into the database????
Some database operations will have return values, such as insert
, modify
, etc. If the operation is successful, it will return true, if it fails, it will return false, and then operate based on the result of the return value;
The questioner said that the insertion failed without writing if
, which means your understanding is wrong. You can assign the execution result of $conn->query($sql)
to a value, such as the following:
<code>$flag = $conn->query($sql); if($flag == TRUE){ //如果返回值为TRUE 说明插入成功 否则就插入失败 echo 'nice!'; }else { echo 'error!'; } </code>
The questioner can take a look at some basic knowledge of databases, and the questions you ask will be easily answered.
SQL statements may fail to execute. For example, the database process suddenly crashes, or the memory explodes, or even high concurrency (the number of mysql queries that an ordinary notebook can execute per second is only a few hundred, and if there are too many, it cannot be executed correctly)
If you want to insert data directly, no problem, just write like this:
<code>$conn->query($sql);</code>
What ifif
or notif
? Anyway, writing this way is OK most of the time and can run, but it is not standardized enough and has hidden dangers.
Because there are two results, one is success and the other is failure. Success has success processing (prompt that the processing is successful), and failure has failure processing (such as prompts for the user to modify the input)
Because writing is actually executed after running to $conn->query($sql)
http://php.net/mysqli
To confirm that inserting a piece of data is successful, two conditions need to be met:
First, there is no syntax error in the SQL statement, which is reflected in query() not returning false.
Second, the affected behavior 1 row, reflected in affected_rows equal to 1.
Other update/delete and other write operations are similar.
<code>if ($mysqli->connect_errno) //判断连接是否成功,错误信息$mysqli->connect_error if ($mysqli->query()) //判断SQL语句执行是否成功,错误编号$mysqli->errno,错误信息$mysqli->error if ($stmt->prepare()) //判断SQL语句预处理是否成功,错误编号$mysqli->errno,错误信息$mysqli->error</code>
<code>CREATE TABLE IF NOT EXISTS mem ( k varchar(32) NOT NULL, v text NOT NULL, t bigint(20) unsigned NOT NULL, PRIMARY KEY (k) USING HASH, KEY (t) USING HASH ) ENGINE=MEMORY DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci; $db = @new mysqli('127.0.0.1','root','pass','yabase',3306); if ($db->connect_errno) { //如密码错误 1045: Access denied for user 'root'@'localhost' (using password: YES) echo $db->connect_errno.': '.$db->connect_error."\n"; exit(); } $db->query("INSERT INTO mem (k, v, t) VALUES ('key1', 'value1', '20160906173140')"); if ($db->errno) { //如主键重复 1062: Duplicate entry 'key1' for key 'PRIMARY' echo $db->errno.': '.$db->error."\n"; exit(); } if ($db->affected_rows == 1) { echo 'affected_rows: '.$db->affected_rows."\n"; }</code>

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。


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