MySQL common functions in PHP (PHP operating database prerequisites)

1. mysql_connect ()-Establish database connection format: Resource mysql_connect ([string hostname [:p ort] [:/path/to/socket] [, string username] [, String Password]]) Example: $conn = @mysql_connect ("localhost", "username", "password") or Die ("Cannot connect to MySQL Server"); Description: Use the connection must display the close connection 2, Mysql_pconnect ()-Establish database connection format: Resource mysql_pconnect ([string hostname [:p ort] [:/path/to/socket] [  , string Username] [, string password]]) Example: $conn = @mysql_pconnect ("localhost", "username", "password") or dir ("Cannot connect to MySQL Server ") Description: Use this connection function does not need to display the closed connection, it is equivalent to using connection Pool 3, mysql_close ()-Close the database connection example: $conn = @mysql_connect (" localhost "," username "," Password ") or Die (" Cannot connect to MySQL Server "), @mysql_select_db (" MyDatabase ") or Die (" cannot select this database, or the database does not exist "); echo" You have connected to the MyDatabase database "; Mysql_close (); 4, mysql_select_db ()-Select database format: Boolean mysql_select_db (String db_name [, Resource LINK_ID]) Example: $conn = @mysql_connect ("localhost", "username", "password") or Die ("Cannot connect to MySQL Server"); @mysql_select_db (" MyDatabase ") or Die (" cannot select this database, or the database does not exist "); 5, mysql_query ()-Query MySQL format: resource mysql_query(string query, [resource link_id]) Example: $linkId = @mysql_connect ("localhost", "username", "password") or Die ("Cannot connect to MySQL Server "), @mysql_select_db (" MyDatabase ") or Die (" cannot select this database, or the database does not exist "); $query =" SELECT * from MyTable "; $result = Mysql_ Query ($query); mysql_close (); Description: Returns the resource identifier if the SQL query execution succeeds, and returns false on failure. Returns true if the update was performed successfully, otherwise returns FALSE6, Mysql_db_query ()-Query MySQL format: Resource mysql_db_query (String database, string query [, Resource link_id]) Example: $linkId = @mysql_connect ("localhost", "username", "password") or Die ("Cannot connect to MySQLServer"); $query = " SELECT * from MyTable "; $result = Mysql_db_query (" MyDatabase ", $query); mysql_close (); Description: To make the code clear, it is not recommended to use this function call 7, Mysql_ Result ()-Gets and displays data format: Mixed mysql_result (Resource result_set, int row [, mixed field]) Example: $query = "SELECT ID, name from Mytab Le order by name ", $result = mysql_query ($query); for ($count =0; $count <=mysql_numrows ($result); $count + +) {$c _id = Mysql_result ($result, 0, "id"), $c _name = mysql_result ($result, 0, "name"), Echo $c _id, $c _name;} Description: The simplest and least efficient data acquisition function 8, Mysql_feTch_row ()-Get and display data format: Array mysql_fetch_row (Resource Result_set) Example: $query = "SELECT ID, name from MyTable order by name"; $re Sult = mysql_query ($query), while (List ($id, $name) = Mysql_fetch_row ($result)) {echo ("Name: $name ($id) <br/>");} Description: The function takes the entire data row from Result_set and places the value in an indexed array. Typically, the list () function is used with 9, mysql_fetch_array ()-Gets and displays the data format: Array mysql_fetch_array (Resource result_set [, int result_type]) Example: $  query = "SELECT ID, name from MyTable order by name"; $result = mysql_query ($query); while ($row = Mysql_fetch_array ($result, MYSQL_ASSOC) {$id = $row ["id"]; $name = $row ["name"];echo "Name: $name ($id) <br/>";} Another example: $query = "SELECT ID, name from MyTable order by name"; $result = mysql_query ($query) and while ($row = Mysql_fetch_array ($res Ult, mysql_num) {$id = $row [0]; $name = $row [1];echo "Name: $name ($id) <br/>";} Description: The value of the Result_type is: Mysql_assoc: The field name represents the key, the field content is the value mysql_num: The numeric index array, the operation is the same as the Mysql_fetch_ros () function Mysql_both: That is, as an associative array and returned as a numeric index array. The default value of the Result_type. 10. MYSQL_FETCH_ASSOC ()-Get and display data format: Array mysql_fetcH_ASSOC (Resource Result_set) is equivalent to calling mysql_fetch_array (resource, MYSQL_ASSOC); 11, mysql_fetch_object ()- Get and display data format: Object Mysql_fetch_object (Resource Result_set) Example: $query = "SELECT ID, name from MyTable order by name", and while ($ro W = mysql_fetch_object ($result)) {$id = $row->id; $name = $row->name;echo "Name: $name ($id) <br/>";} Description: Returns an object that has the same operation as Mysql_fetch_array () 12, mysql_num_rows ()-The number of records selected in the format: int mysql_num_rows (Resource result_set) Example: query = "SELECT ID, name from MyTable where ID >"; $result = mysql_query ($query); echo "has". Mysql_num_rows ($result). " The ID of the record is greater than 65 "; Description: Only used when determining the number of records fetched by the select query. 13, Mysql_affected_rows ()-The number of records affected by Insert,update,delete format: int mysql_affected_rows ([resource link_id]) Example: $query = " Update MyTable set name= ' Cheneyfu ' where id>=5 '; $result = mysql_query ($query); echo "ID is greater than or equal to 5 the number of records that the name was updated:". Mysql_ Affected_rows (); Description: This function gets the number of rows affected by the Insert,update or delete UPDATE statement 14, Mysql_list_dbs ()-Gets the database list Information Format: Resource Mysql_list_dbs ([ Resource link_id]) Example: mysql_connect ("localhost", "username", "Password "); $dbs = Mysql_list_dbs (); echo" Databases: <br/> "while (list ($db) = Mysql_fetch_rows ($dbs)) {echo $db & Lt;br/> ";} Description: Show all database names 15, Mysql_db_name ()-Gets the database name format: String mysql_db_name (Resource Result_set, integer index) Description: The function gets the Mysql_ List_dbs () returns the database name at the specified index index in Result_set 16, mysql_list_tables ()-Gets the Database table column table format: Resource Mysql_list_tables (string database [, Resource link_id]) Example: mysql_connect ("localhost", "username", "password"), $tables = Mysql_list_tables (" MyDatabase "), while (list ($table) = Mysql_fetch_row ($tables)) {echo" $table <br/> ";} Description: This function gets the table name 17, Mysql_tablename () of all tables in database-gets the format of a database table name: String Mysql_tablename (Resource Result_set, integer index) Example: mysql_connect ("localhost", "username", "password"), $tables = Mysql_list_tables ("MyDatabase"); $count = -1;while (++$ Count < Mysql_numrows ($tables)) {echo mysql_tablename ($tables, $count). " <br/> ";} Description: This function gets the table name 18, Mysql_fetch_field ()-Get field information format in Result_set returned by Mysql_list_tables () in the specified index index: Object Mysql_fetch_field (Resource reSult [, int field_offset]) Example: mysql_connect ("localhost", "username", "password"); mysql_select_db ("MyDatabase"); $query = "SELECT * from MyTable", $result = mysql_query ($query), $counts = Mysql_num_fields ($result); for ($count = 0; $count < $c ounts; $count + +) {$field = Mysql_fetch_field ($result, $count); echo "<p> $field->name $field->type ($field->max _length) </p> ";} Description: The returned object has a total of 12 object properties: Name: Field Name table: Field Max_length: The maximum length of the field Not_null: If the field cannot be null, then 1, otherwise 0primary_key: 1 if the field is a primary key; Otherwise 0unique_key: If the field is a unique key, then 1, otherwise 0multiple_key: 1 if the field is not unique, otherwise 0numeric: If the field is numeric then 1, otherwise 0blob: if it is a blob then 1, otherwise 0type: The data type of the field unsigned: 1 if the field is unsigned, otherwise 0zerofill: 1 if the field is 0 filled, otherwise 019, Mysql_num_fields ()-Gets the number of fields in the query format: integer mysql_num _fields (Resource Result_set) Example: $query = "Select Id,name from MyTable order by name"; $result = mysql_query ($query); echo "This check The number of fields polled is: ". Mysql_num_fields ($result)." <br/> "; 20, Mysql_list_fields ()-Gets the field name format for all fields of the specified table: Resource Mysql_list_fields (string database_name, string table _nAme [, Resource link_id]) Example: $fields =mysql_list_fields ("MyDatabase", "MyTable"), echo "Number of fields in table MyDatabase in database MyTable:". Mysql_num_fields ($fields). " <br/> "; 21, Mysql_field_flags ()-Gets the specified field option format: String mysql_field_flags (Resource Result_set, Integer field_offset Example: $query = "SELECT ID, name from MyTable order by name"; $result = mysql_query ($query); $row =mysql_fetch_wor ($row); 22, MYSQ L_field_len ()-Gets the maximum length format for the specified field: Integer mysql_field_len (Resource result_set, integer field_offset) Example: $query = "Select Name from MyTable "; $result = mysql_query ($query); $row = Mysql_fetch_row ($result); Echo Mysql_field_len ($result, 0)." <br/> "; Description: If Mysql_field_len ($reseult, 0) = 16777215 then Numer_format (Mysql_field_len ($result)) equals 16,777,21523, Mysql_field_name ()-Gets the field name format: String mysql_field_name (Resource result_set, int field_offset) Example: $query = "SELECT ID as PKID, Name from MyTable order by name "; $result = mysql_query ($query); $row = Mysql_fetch_row ($result); Echo Mysql_field_name ($ result, 0); RESULT:PKID24, Mysql_fieLd_type ()-Gets the field type format: String Mysql_field_type (Resource result_set, int field_offset) Example: $query = "SELECT ID, name from MYTABL E order by name "; $result = mysql_query ($query); $row = Mysql_fetch_row ($result); Echo mysql_field_type ($result, 0); Result:int25, mysql_field_table ()-Gets the table name format in which the field is located: String mysql_field_table (Resource result_set, int Field_offset) Example: $ query = "SELECT ID as PKID, name from MyTable order by name"; $result = mysql_query ($query); $row = Mysql_fetch_row ($result) ; Echo mysql_field_table ($result, 0);  Result:mytable
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MySQL common functions in PHP (PHP operating database prerequisites)