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PHP comes with a process-oriented database connection method, and the following common methods are generally used. The specific steps are as follows:
1. Create a database connection:
$db_connect=mysql_connect($dbhost,$username,$userpass) or die("Unable to connect to the MySQL!");
This connection is a non-persistent connection, where $dbhost is the configuration of the host, usually localhost, and the port number of the connection can also be specified. , generally 3306 is used by default. $username is the username to connect to the database. $userpass is the password.
The return value is the connection type after a successful connection, and false when it fails.
2, select the database to operate.
mysql_select_db($databasename,$db_connect);
$databasenameNot the database name, the second parameter is the connection and can be empty. The return value is bool.
The PHP manual explains the second parameter as follows: MySQL connection. If the connection ID is not specified, the most recently opened connection by <span class="function">mysql_connect()</span> is used. If the connection is not found, it will try to create it by calling <span class="function">mysql_connect()</span> without parameters. If a connection is not found or cannot be established, an E_WARNING level error will be generated.
3, execute sql statement.
mysql_query($sql);
Execute a sql statement. If the sql is of type select, show, etc., the result set of the query will be returned if successful, and FALSE will be returned if it fails. If it is insert delete update, the returned value is bool type.
The above are the three basic steps. The following is a more comprehensive method description of the mysql function library.
| 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 pointer. |
| mysql_db_query: | Send the 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 class information. |
| mysql_fetch_row: | Returns each field of a single column. |
| mysql_field_name: | Returns the name of the specified field. |
| mysql_field_seek: | Configure the pointer to a field of the return value. |
| mysql_field_table: | Get the table name 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. |
| 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: | List the databases available to the MySQL server. |
| mysql_list_tables: | List the data tables (tables) of the specified database. |
| mysql_num_fields: | Get the number of fields returned. |
| mysql_num_rows: | Get the number of returned columns. |
| mysql_pconnect: | Open a persistent connection to the MySQL server. |
| mysql_query: | Send a query string. |
| mysql_result: | Get the result of the query. |
| mysql_select_db: | Select a database. |
| mysql_tablename: | Get the name of the data table. |
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