Summary of some common operations that php operates mysql to perform database queries

php Operation mysql steps:
$connect=mysql_connect('localhost','root','123456') or die(' database connection failed. 'mysql_error ()); Link mysql.
mysql_select_db('database',$connect) selects the linked database.
3. mysql_query (' Set names gb2312 '); $sql = "select * from blog_article"; Prepare the data to be queried.
4. $datas = mysql_query ($sql); Execute the sql query.
$data = mysql_fetch_assoc($datas) gets a cached piece of data that was queried.
6.print_r($data);

The same: Each of the three functions returns 1 row of data in the database (to be clear, 1 row of data).
Difference: mysql_fetch_assoc() USES the corresponding field name in the database as the key value (that is, the array index)
Such as: filed [' id] = 1;
mysql_fetch_row() USES the automatically generated Numbers (generated in sequence from 0) as the key value (i.e., array subscripts)
Such as: filed [0] = 1;
mysql_fetch_array() USES the automatically generated number (generated in sequence from 0) as the key value (that is, the array index), and it also generates the corresponding field name in the database as the key value (that is, the array index)
Such as:
filed [0] = 1, filed [' id] = 1; That is, mysql_fetch_array() combines the results of mysql_fetch_assoc() and mysql_fetch_row() into one body.
mysql_fetch_object() is similar to mysql_fetch_assoc(). Only mysql_fetch_assoc() returns an array. mysql_fetch_object() returns the object object.
mysql_insert_id() retrieves the ID generated by the previous step INSERT operation.
The mysql_result() function returns the value of one field in the result set.
The mysql_num_fields() function returns the number of fields in the result set.
mysql_affected_rows (); Returns the number of record rows affected by the previous MySQL operation.
mysql_num_rows(mysql_query($sql)) gets the number of rows in the result set.
The mysql_pconnect() function opens a persistent connection to the MySQL server.

mysql_pconnect() and mysql_connect() are very similar, but there are two main differences:
1. When connecting, this function will first try to find a (persistent) connection that has been opened on the same host with the same user name and password. If found, this connection id will be returned without opening a new connection.
2. Second, the connection to the SQL server will not be closed after the script is executed, and this connection will remain open for later use (mysql_close() will not close the connection established by mysql_pconnect()).
mysql_data_seek (mysql_query ($sql), 8). Get the 8th data in the result set. (mysql_num_rows(mysql_query($sql)) and mysql_data_seek($sql),8) are not available on mysql_unbuffered_query($sql).
mysql_unbuffered_query($sql) and mysql_query($sql) have similar effects, however
mysql_unbuffered_query($sql) not cached. mysql_query($sql) caches the results of the query.
mysql_close (); Close the nearest link for mysql.
mysql_field_flags(mysql_query($sql),6) returns the table property output for the sixth field, not_null primary_key auto_increment.
mysql_fetch_lengths(mysql_query($sql)) returns the length of each field for all fields of this data. Returns an array of 1 number.
mysql_field_name(mysql_query($sql),3) returns the field name of the third field.
mysql_field_table(mysql_query($sql),0) returns the table name of the specified field.
The mysql_free_result(mysql_query($sql)) function frees the result memory.
The mysql_get_client_info() function returns MySQL client information.
mysql_get_host_info() gets MySQL host information.