PHP uses pdo to connect to the access database and display data operations in a loop

This article mainly introduces the operation of PHP using pdo to connect to the access database and display the data in a loop. It analyzes in detail the operation skills and related operations of PHP using pdo to connect to the access database, query, execute sql statements, preprocessing, etc. in the form of examples. Notes, friends in need can refer to

This article describes the example of PHP using pdo to connect to the access database and display the data in a loop. Share it with everyone for your reference, the details are as follows:

PDO connection and query:

try {
$conn = new PDO("odbc:driver={microsoft access driver (*.mdb)};
       dbq=".realpath("MyDatabase.mdb"))
       or die("链接错误！");
//echo "链接成功！";
}
catch(PDOException $e){
  echo $e->getMessage();
}
$sql = "select * from users";

1. foreach()Method

foreach ($conn->query($sql) as $row) {
$row["UserID"];
$row["UserName"];
$row["UserPassword"];
}

2. while()Method

$rs = $conn->query($sql);
$rs->setFetchMode(PDO::FETCH_NUM);
while($row=$rs->fetch()){
$row[0];
$row[1];
$row[2];
}

php uses the PDO abstraction layer to obtain query results. There are three main ways:

(1) PDO::query()Query.

Look at the following php code:

<?php
//PDO::query()查询
$res = $db->query(&#39;select * from user&#39;);
$res->setFetchMode(PDO::FETCH_NUM); //数字索引方式
while ($row = $res->fetch()){
print_r($row);
}
?>

(2)PDO->exec()Processing sql

<?php
//PDO->exec()处理sql
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$res = $db->exec("insert into user(id,name) values(&#39;&#39;,&#39;php点点通&#39;)");
echo $res;
?>

（3）PDO::prepare()Preprocessing execution query

<?php
//PDO::prepare()预处理执行查询
$res = $db->prepare("select * from user");
$res->execute();
while ($row = $res->fetchAll()) {
print_r($row);
}
?>

setAttribute() The method is to set attributes. Common parameters are as follows:

PDO::CASE_LOWER -- Force column names to be lowercase
PDO::CASE_NATURAL -- Column names are in original form
PDO::CASE_UPPER -- Force column names to be uppercase

setFetchModeMethod to set the type of return value for obtaining the result set. Common parameters are as follows:

PDO::FETCH_ASSOC -- Associative array form
PDO::FETCH_NUM -- Numeric index array form
PDO::FETCH_BOTH -- Both array forms are available, this is the default
PDO::FETCH_OBJ -- Follow The form of the object is similar to the previous mysql_fetch_object()

The above is summarized as follows:

The query operation is mainly PDO::query(), PDO: :exec(), PDO::prepare().

PDO->query() — Process a SQL statement and return a "PDOStatement"
PDO->exec() — Process a SQL statement, and returns the number of affected entries
PDO::prepare()Mainly a preprocessing operation, you need to execute the SQL statement in the preprocessing through $rs->execute()

Finally, two commonly used functions are introduced:

(1)fetchColumn()Get the result of a field in the specified record, the default is the first one Field!

<?php
$res = $db->query(&#39;select * from user&#39;);
//获取指定记录里第二个字段结果
$col = $res->fetchColumn(1);
echo $col;
?>

(2)fetchAll(), get data from a result set, and then store it in an associative array

<?php
$res = $db->query(&#39;select * from user&#39;);
$res_arr =$res->fetchAll();
print_r($res_arr);
?>

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