PHP database connection code application analysis_PHP tutorial

Copy code The code is as follows:

$db_host='hostname is database server ';
$db_database='database name';
$db_username='username';
$db_password='password';
$connection=mysql_connect($db_host,$db_username,$db_password);// Connect to the database
mysql_query("set names 'utf8'");//Encoding conversion
if(!$connection){
die("could not connect to the database:
" .mysql_error());//Diagnosis connection error
}
$db_selecct=mysql_select_db($db_database);//Select database
if(!$db_selecct)
{
die(" could not to the database
".mysql_error());
}
$query="select * from msu ";//Build query statement
$result=mysql_query($query); //Execute query
if(!$result)
{
die("could not to the database
".mysql_error());
}
// array mysql_fetch_row (resource $result);
while($result_row=mysql_fetch_row(($result)))//Get the result and display it
{
$num=$result_row[0];
$age= $result_row[1];
$name=$result_row[2];
echo "";
echo "$num";
echo "$age";
echo "$name";
echo "";
}
mysql_close ($connection);//Close the connection
?>

The following is the code with detailed instructions

Copy code The code is as follows:

$connect = mysql_connect("127.0.0.1","root","") or die ("Link Error");//Open the link to mysql
$ select_db = mysql_select_db("database name",$connect);//If the connection identifier is not specifically declared, the last opened link will default to
//Execute the SQL statement!
$sql = "SELECT * FROM test"
$query = mysql_query($sql,$connect) or die(mysql_error());

//The difference between the two query functions array/row
$row1 = mysql_fetch_row($query);
print_r($row1);//Only labels in the array can be saved
$row2 = mysql_fetch_array($query);
print_r($row2) ;//You can save labels and field names in the array
//Loop output while output to an empty position
while($row1){
print_r($row1);
}

mysql_query("SET NAMES 'UTF-8'");

//Used to calculate the number of query results
mysql_num_rows($query);
//Return the last used IP of INSERT command
mysql_insert_id($query);
//Get the database name
mysql_tablename($query);
//Return error message
mysql_error();
// Close link
mysql_close();

Common functions for PHP to connect to mySQL
Mysql can be connected to the web through PHP in two ways, one through php's Mysql-related functions, and the other through php's ODBC-related functions.
The related functions are as follows:
MYSQL function
mysql_affected_rows: Get the number of columns affected by the last MySQL operation.
mysql_close: Close the MySQL server connection.
mysql_connect: Open the MySQL server connection.
mysql_create_db: Create a new MySQL database.
mysql_data_seek: Move the internal return indicator.
mysql_db_query: Send query string (query) to the MySQL database.
mysql_drop_db: Remove the database.
mysql_errno: Return error message code.
mysql_error: Return error message.
mysql_fetch_array: Return array data.
mysql_fetch_field: Get field information.
mysql_fetch_lengths: Returns the maximum length of each column of data in a single column.
mysql_fetch_object: Return object data.
mysql_fetch_row: Returns each column of a single column.
mysql_field_name: Returns the name of the specified field.
mysql_field_seek: Set the indicator to a field of the returned value.
mysql_field_table: Get the name of the data table (table) of the current field.
mysql_field_type: Get the type of the current field.
mysql_field_flags: Get the flags of the current field.
mysql_field_len: Get the length of the current field.
mysql_free_result: Release the occupied memory returned.
mysql_insert_id: Returns the ID of the last INSERT instruction used.
mysql_list_fields: List the fields of the specified data table.
mysql_list_dbs: Lists the databases available on the MySQL server.
mysql_list_tables: List the tables (tables) of the specified database.
mysql_num_fields: Get the number of fields returned.
mysql_num_rows: Get the number of columns returned.
mysql_pconnect: Enable long-term connection to MySQL server.
mysql_query: Send a query string.
mysql_result: Get the result of query.
mysql_select_db: Select a database.
mysql_tablename: Get the name of the data table.
ODBC function
To use ODBC function, you need to install MYSQL ODBC
odbc_autocommit: switch the automatic change function.
odbc_binmode: Set the binary data processing method.
odbc_close: Close the ODBC connection.
odbc_close_all: Close all ODBC connections.
odbc_commit: Modify the ODBC database.
odbc_connect: Connect to ODBC database.
odbc_cursor: Get the cursor name.
odbc_do: Execute SQL instructions.
odbc_exec: Execute SQL instructions.
odbc_execute: Execute preset SQL instructions.
odbc_fetch_into: Get the specified column returned.
odbc_fetch_row: Get and return a column.
odbc_field_name: Get the field name.
odbc_field_type: Get the field data form.
odbc_field_len: Get the field data length.
odbc_free_result: Release the memory of the returned data.
odbc_longreadlen: Set the maximum value of the returned column.
odbc_num_fields: Get the number of fields.
odbc_pconnect: Long-term connection to ODBC database.
odbc_prepare: Prepare SQL instructions.
odbc_num_rows: Get the number of returned columns.
odbc_result: Get the returned data.
odbc_result_all: Return HTML table data.
odbc_rollback: Undo the current transaction.
odbc_setoption: Adjust ODBC settings.

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