Detailed explanation of PHP operation mysql function, mysql and php interactive function_PHP tutorial

1. Establish and close connections
1) mysql_connect()
resource mysql_connect([string hostname [:port][:/path/to/socket][,string username] [,string password]])
All parameters are optional
Example:
@mysql_connect(“localhost”, “user”, “password”)
or die(“Could not connect to mysql server !");
Note that the @ symbol means that any error message caused by a failed attempt is prohibited. What the user will see is the error message specified in die().
Note that when connecting to multiple mysql, The link ID of each connection must be specified, as follows:
$link1 = @mysql_connect(“server1″, “user”, “password”)
or die(“Could not connect to mysql server!”);
$link2 = @mysql_connect(“server2″, “user”, “password”)
or die(“Could not connect to mysql server!”);
2) mysql_pconnect()
resource mysql_pconnect ([string hostname [:port][:/path/to/socket][,string username] [,string password]])
The difference from mysql_connect() is: it will first search for the existing link, if it does not exist
Note that there is no need to explicitly close the connection (mysql_close()), because the connection will be placed in the pool, so it is called a persistent connection.
3) mysql_close()
boolean mysql_close([resource link_id] )
Closing the connection is not necessary because it can be handled by MySQL's garbage collection.
If link_id is not specified, the most recent link is closed.
2. Select the database
mysql_select_db()
boolean mysql_select_db(string db_name [, resource link_id])
3. Query MySql
1) mysql_query()
resource mysql_query(string query [, resource link_id ])
Responsible for executing query.
2) mysql_db_query()
resource mysql_db_query(string database, string query [, resource link_id])
Equivalent to mysql_select_db() + mysql_query(), from the parameters You can clearly see it in.
4. Obtain and display data
1) mysql_result()
mixed mysql_result(resource result_set, int row [,mixed field])
Get the data of a field from the specified row of result_set. Simple but inefficient.
Example:

Copy code The code is as follows:

$link1 = @mysql_connect(“server1″, “webuser”, “password”)
or die(“Could not connect to mysql server!”);
@mysql_select_db(“company”) or die(“Could not select database!”);
$query = “select id, name from product order by name”;
$result = mysql_query($query);
$id = mysql_result( $result, 0, “id”);
$name = mysql_result($result, 0, “name”);
mysql_close();

Note that the above code is just output The field value of the first piece of data in the result set, if you want to output all records, needs to be processed in a loop.

Copy code The code is as follows:

…
for ($i = 0; $i <= mysql_num_rows($result); $i++)
{
$id = mysql_result($result, 0, “id”);
$name = mysql_result($result, 0, “name”);
echo “Product: $name ($id)”;
}
…

Note that if the query field name is an alias, the alias will be used in mysql_result.
2) mysql_fetch_row()
array mysql_fetch_row(resource result_set)
Get the entire row from result_set and put the data into the array.
Example (pay attention to the clever combination with list):

Copy code The code is as follows:

…
$ query = “select id, name from product order by name”;
$result = mysql_query($query);
while(list($id, $name) = mysql_fetch_row($result)) {
echo “Product: $name ($id)”;
}
…

3) mysql_fetch_array()
array mysql_fetch_array(resource result_set [,int result_type])
An enhanced version of mysql_fetch_row().
Get each row of result_set as an associative array or/and a numerical index array.
Get two arrays by default, result_type can be set:
MYSQL_ASSOC: Returns an associative array, Field name => Field value
MYSQL_NUM: Returns a numerical index array.
MYSQL_BOTH: Gets two arrays. Therefore, each field can be referenced by index offset or by field name.
Example:

Copy code The code is as follows:

…
$query = “select id, name from product order by name” ;
$result = mysql_query($query);
while($row = mysql_fetch_array($result, MYSQL_BOTH)) {
$name = $row['name'];//or $name = $row[1];
$name = $row['id'];//or $name = $row[0];
echo “Product: $name ($id)”;
}
…

4) mysql_fetch_assoc()
array mysql_fetch_assoc(resource result_set)
Equivalent to mysql_fetch_array($result, MYSQL_ASSOC)
5) mysql_fetch_object()
object mysql_fetch_object(resource result_set)
and mysql_fetch_array() has the same function, but it returns an object instead of an array.
Example:

Copy code The code is as follows:

…
$query = “select id, name from product order by name”;
$result = mysql_query($query);
while($row = mysql_fetch_object($result)) {
$name = $row->name;
$name = $row->id;
echo “Product: $name ($id)”;
}
…

5. Selected records and affected records
1) mysql_num_rows()
int mysql_num_rows(resource result_set)
Return the rows in result_set Number.
Note that mysql_num_rows() is only effective in determining the number of records obtained by the select statement query. If you want to obtain the number of records affected by the insert/updata/delete query, you need to use mysql_affected_rows().
2) mysql_affected_rows()
int mysql_affected_rows([resource link_id])
Get the number of records affected by the insert/updata/delete query
Note that no parameters are required and the most recent result of the most recently established database connection is used by default. You can use optional Parameter link_id to select the database connection.
6. Get database and table information
1) mysql_list_dbs()
resource mysql_list_dbs([resource link_id])
Get all the information on the server Database name.
Example:

Copy code The code is as follows:

mysql_connect(“localhost”, “name”, "pwd");
$dbs = mysql_list_dbs();
while (list($db) = mysql_fetch_row(dbs)) {
echo "$db
";
}

Note that the output results are related to the user permissions used.
2) mysql_db_name()
string mysql_db_name(resource result_set, interger index)
Get the result_set returned in mysql_list_dbs() The database name with the center position as index.
3) mysql_list_tables()
resource mysql_list_tables(string database [,resource link_id])
Get all table names in the database.
4) mysql_tablename()
string mysql_tablename(resource result_set, interger index)
Get the table name at index in the result_set returned by mysql_list_tables().
While learning PHP’s COM and .Net (Windows) functions, I discovered a I found the example of operating SQL SERVER through COM and found relevant information, so I came up with this article about connecting ACCESS with PHP. I believe there are already many on the Internet, so I’ll post it here.
My machine environment: WIN2000, APACHE2, PHP Version 5.1.0RC1

Copy code The code is as follows:

< ;?php
$conn = new COM(“ADODB.Connection”) or die(“Cannot start ADODB.Connection”);
$conn->Open(“Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source=D:\php5\netBook.mdb”);
$rs = $conn->Execute(“select * from manage”); // Recordset
$num_columns = $rs-> ;Fields->Count();
echo $num_columns . “
n”;
for ($i=0; $i < $num_columns; $i++) {
$fld[$i] = $rs->Fields($i);
}
$rowcount = 0;
while (!$rs->EOF) {
for ($ i=0; $i < $num_columns; $i++)
{
echo htmlspecialchars($fld[$i]->value) . “t”;
}
echo “< ;br />n”;
$rowcount++; // rowcount increments
$rs->MoveNext();
}
$rs->Close(); //Close Dataset
$conn->Close();
?>

http://www.bkjia.com/PHPjc/323308.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/323308.htmlTechArticle1. Establishing and closing connections 1) mysql_connect() resource mysql_connect([string hostname [:port][:/ path/to/socket][,string username] [,string password]]) All parameters are optional. Example...