PHP connection mode PDO use detailed, PDO Wan apply Xuan "в_php tutorial

MySQL connection in PHP PDO use detailed, PDO WAN apply Xuan "в

PDO Common methods:

Pdo::query () is primarily used for operations (pdostatement) that have logged results returned, especially for select operations.

Pdo::exec () is primarily for operations returned without a result set. such as Insert,update and other operations. Returns the number of affected rows.
Pdo::lastinsertid () returns the last ID of the last insert operation, but note that if you use INSERT into TB (col1,col2) VALUES (V1,V2), (V11,V22): By inserting multiple records at once, Lastinsertid () returns only the ID of the first (V1,V2) insert, not the record ID that was inserted in the last record.
Pdostatement::fetch () is used to get a record. With while to traverse.
Pdostatement::fetchall () is to get all recordsets into one.
Pdostatement::fetchcolumn ([int column_indexnum]) is used for direct access to the column, and the parameter column_indexnum is the 0-based index value in the row of the column, but this method can only get one row at a time. Once executed, jump to the next line. Therefore, it is better to use for direct access to a column, but it is not useful to traverse multiple columns.
Pdostatement::rowcount () is used when using the query ("SELECT ...") method to get the number of records. can also be used in preprocessing. $stmt->rowcount ();
Pdostatement::columncount () is used when using the query ("SELECT ...") method to get the number of columns of a record.

Annotations:
1, pick or fetchall?
Small record set, with fetchall efficiency, reduce the number of retrieval from the database, but for large result sets, with Fetchall to the system brings a great burden. The database is too large to transmit to the web front end and inefficient.
2. Fetch () or Fetchall () has several parameters:
Mixed Pdostatement::fetch ([int fetch_style [, int cursor_orientation [, int cursor_offset]])
Array pdostatement::fetchall (int fetch_style)

Fetch_style Parameters:
$row = $rs->fetchall (pdo::fetch_both); Fetch_both is the default, can be saved, returns associations and indexes.
$row = $rs->fetchall (PDO::FETCH_ASSOC); The FETCH_ASSOC parameter determines that only the associative array is returned.
$row = $rs->fetchall (pdo::fetch_num); Returns an indexed array
$row = $rs->fetchall (pdo::fetch_obj); If fetch () returns the object, and if it is Fetchall (), returns a two-dimensional array consisting of the object

Copy CodeThe code is as follows:
<?php
$DBH = new PDO (' Mysql:host=localhost;dbname=access_control ', ' root ', ');
$DBH->setattribute (Pdo::attr_errmode, pdo::errmode_exception);
$DBH->exec (' Set names UTF8 ');
/* Add */
$sql = "INSERT into ' user ' SET ' login ' =:login and ' password ' =:p assword";
$sql = "INSERT into ' user ' (' login ', ' password ') VALUES (: Login,:p assword)"; $stmt = $dbh->prepare ($sql); $stmt->execute (': Login ' = ' kevin2 ', ':p assword ' = ') ');
echo $DBH->lastinsertid ();
/* Modify */
$sql = "UPDATE ' user ' SET ' password ' =:p assword WHERE ' user_id ' =:userid";
$stmt = $dbh->prepare ($sql);
$stmt->execute (Array (': userId ' = ' 7 ', ':p assword ' = ' 4607e782c4d86fd5364d7e4508bb10d9 '));
echo $stmt->rowcount ();
/* Delete */
$sql = "DELETE from ' user ' WHERE ' login ' like ' kevin_ '"; kevin%
$stmt = $dbh->prepare ($sql);
$stmt->execute ();
echo $stmt->rowcount ();
/* Query */
$login = ' kevin% ';
$sql = "SELECT * from ' user ' WHERE ' login ' Like:login";
$stmt = $dbh->prepare ($sql);
$stmt->execute (Array (': Login ' = $login));
while ($row = $stmt->fetch (PDO::FETCH_ASSOC)) {
Print_r ($row);
}
Print_r ($stmt->fetchall (PDO::FETCH_ASSOC));
?>

1 Establishing the connection

Copy the Code code as follows:
<?php
$DBH =newpdo (' mysql:host=localhost;port=3306; Dbname=test ', $user, $pass, Array (
Pdo::attr_persistent=>true
));
?>

Persistent link Pdo::attr_persistent=>true

2. Catching errors

Copy the Code code as follows:
<?php
try{
$DBH =newpdo (' mysql:host=localhost;dbname=test ', $user, $pass);
$DBH->setattribute (pdo::attr_errmode,pdo::errmode_exception);
$DBH->exec ("Set CHARACTER set UTF8");
$DBH =null; Disconnect Connection
}catch (pdoexception$e) {
Print "error!:". $e->getmessage (). "
";
Die ();
}
?>

3. The Business

Copy the Code code as follows:
<?php
try{
$DBH->setattribute (pdo::attr_errmode,pdo::errmode_exception);
$DBH->begintransaction ();//Open transaction
$DBH->exec ("Insertintostaff (Id,first,last) VALUES (+, ' Joe ', ' Bloggs ')");
$DBH->exec ("Insertintosalarychange (id,amount,changedate)
VALUES (23,50000,now ()) ");
$DBH->commit ();//Commit a transaction
}catch (exception$e) {
$DBH->rollback ();//Error rollback
echo "Failed:". $e->getmessage ();
}
?>

4. Error handling

A. Silent mode (default mode)

The

copy Code code is as follows:
$dbh->setattribute (pdo::attr_errmode,pdo::errmode_silent);//Do not display error
$ Dbh->setattribute (Pdo::attr_errmode, pdo::errmode_warning);//Displays a warning error and continues execution of
$dbh->setattribute (pdo::attr _errmode,pdo::errmode_exception);//Generate fatal error, pdoexception

Copy the Code code as follows:
<?php
try{
$DBH = new PDO ($DSN, $user, $password);
$sql = ' Select * from city where CountryCode =:country ';
$DBH->setattribute (Pdo::attr_errmode, pdo::errmode_warning);
$stmt = $dbh->prepare ($sql);
$stmt->bindparam (': Country ', $country, PDO::P aram_str);
$stmt->execute ();
while ($row = $stmt->fetch (PDO::FETCH_ASSOC)) {
Print $row [' Name ']. "/t";
}
}//If there is a problem we can handle it here
catch (Pdoexception $e) {
Echo ' PDO Exception caught. ';
Echo ' Error with the database:
';
Echo ' SQL Query: ', $sql;
Echo ' Error: '. $e->getmessage ();
}
?>

1. Use Query ()

Copy the Code code as follows:
<?php
$DBH->query ($sql); When the $sql variable can be used $dbh->quote ($params); Escaping the data of a string
$sql = ' Select * from city where CountryCode = '. $dbh->quote ($country);
foreach ($dbh->query ($sql) as $row) {
Print $row [' Name ']. "/t";
Print $row [' CountryCode ']. "/t";
Print $row [' Population ']. "/n";
}
?>

2. Use prepare, Bindparam and execute [recommended, and can be added, modified, deleted]

Copy the Code code as follows:
<?php
$DBH->prepare ($sql); Produced a Pdostatement object.

Pdostatement->bindparam ()

Pdostatement->execute ();//You can put the corresponding variable of the binding here
?>

3. Things

Copy the Code code as follows:
<?php
try {
$DBH = new PDO (' Mysql:host=localhost;dbname=test ', ' root ', ');
$DBH->query (' Set names utf8; ');
$DBH->setattribute (Pdo::attr_errmode, pdo::errmode_exception);
$DBH->begintransaction ();
$DBH->exec (' Insert into ' test ', ' table ' (' Name ', ' age ') VALUES (' Mick ', 22); ");
$DBH->exec ("Insert into ' test ') ' table ' (' Name ', ' age ') VALUES (' Lily ', 29);");
$DBH->exec ("Insert into ' test ') ' table ' (' Name ', ' age ') VALUES (' Susan ', 21);");
$DBH->commit ();
} catch (Exception $e) {
$DBH->rollback ();
echo "Failed:". $e->getmessage ();
}
?>

The above is about the use of PDO in PHP all the content, I hope this article can help you, but also hope that we can like.

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