Use the mysql_query() function to execute SQL statements

mysql_query() function

In the PHP MySQL function library, the mysql_query() function is used to send and execute SQL statements to MySQL.

For SQL that does not return a result set with data, such as UPDATE, DELETE, etc., TRUE is returned when the execution is successful, and FALSE is returned when an error occurs; for SELECT, SHOW, EXPLAIN or DESCRIBE statements, a resource is returned Identifier, returns FALSE if the query was executed incorrectly.

mysql_query() syntax:

resource mysql_query( string query [, resource connection] )

mysql_query() parameter description:

Parameter	Description
query	SQL statement to send query
connection	Optional, Connect to the databaseIdentifies the resource, if not specified, the previous connection will be used

Prompt

If there is no open connection, this function will try to call the mysql_connect() function without parameters to establish a connection

For queries that return dataset, even if The return result is 0 (that is, there are no records that meet the query conditions), and the resource identifier is still returned instead of FALSE

Example 1:

<php
$conn = @mysql_connect("localhost","root","root123");
if (!$conn){
   die("连接数据库失败：" . mysql_error());
}
mysql_select_db("test", $conn);
$result = mysql_query("SELECT * WHERE 1=1")
    or die("无效查询: " . mysql_error());
?>

The query statement in this example has an error in SQL syntax , so mysql_query() fails and returns FALSE.

Example 2:

<php
$conn = @mysql_connect("localhost","root","root123");
if (!$conn){
    die("连接数据库失败：" . mysql_error());
}
mysql_select_db("test", $conn);
mysql_query("set names &#39;gbk&#39;");//为避免中文乱码做入库编码转换
$password = md5("123456");//原始密码 12345 经过加密后得到加密后密码
$regdate = time();//得到时间戳
$sql = "INSERT INTO user(username, password, email, regdate)VALUES(&#39;小王&#39;, &#39;$password&#39;,
 &#39;12345@163.com&#39;, $regdate)";
if(!mysql_query($sql,$conn)){
    echo "添加数据失败：".mysql_error();
} else {
    echo "添加数据成功！";
}
?>

This example writes data to the user table and returns TRUE successfully, otherwise it returns FALSE (use the ! symbol to judge).

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