PDO::exec()

(PHP 5 >= 5.1.0, PHP 7, PECL pdo >= 0.1.0)

执行一条 SQL 语句，并返回受影响的行数

说明

PDO::exec(string $statement): int

PDO::exec()在一个单独的函数调用中执行一条 SQL 语句，返回受此语句影响的行数。

PDO::exec()不会从一条 SELECT 语句中返回结果。对于在程序中只需要发出一次的 SELECT 语句，可以考虑使用PDO::query()。对于需要发出多次的语句，可用PDO::prepare()来准备一个 PDOStatement 对象并用PDOStatement::execute()发出语句。

参数

$statement

要被预处理和执行的 SQL 语句。

查询中的数据应该被妥善地转义。

返回值

PDO::exec()返回受修改或删除 SQL 语句影响的行数。如果没有受影响的行，则PDO::exec()返回 0。

Warning

此函数可能返回布尔值FALSE，但也可能返回等同于FALSE的非布尔值。请阅读布尔类型章节以获取更多信息。应使用===运算符来测试此函数的返回值。

下面例子依赖PDO::exec()的返回值是不正确的，其中受影响行数为 0 的语句会导致调用die()：

<?php
$db->exec() or die(print_r($db->errorInfo(), true));
?>

范例

发出一条 DELETE 语句

计算由一条不带 WHERE 字句的 DELETE 语句删除的行数。

<?php
$dbh = new PDO('odbc:sample', 'db2inst1', 'ibmdb2');
/*  删除 FRUIT 数据表中满足条件的所有行 */
$count = $dbh->exec("DELETE FROM fruit WHERE colour = 'red'");
/* 返回被删除的行数 */
print("Deleted $count rows.\n");
?>

以上例程会输出：

Deleted 1 rows.

参见

• PDO::prepare() 准备要执行的语句，并返回语句对象
• PDO::query() 执行 SQL 语句，以 PDOStatement 对象形式返回结果集
• PDOStatement::execute() 执行一条预处理语句

This function cannot be used with any queries that return results. This includes SELECT, OPTIMIZE TABLE, etc.

PDO::eval() might return `false` for some statements (e.g. CREATE TABLE) even if the operation completed successfully, when using PDO_DBLIB and FreeTDS. So it is not a reliable way of testing the op status.
PDO::errorInfo() can be used to test the SQLSTATE error code for '00000' (success) and '01000' (success with warning).
<?php
function execute(PDO $conn, $sql) {
  $affected = $conn->exec($sql);
  if ($affected === false) {
    $err = $conn->errorInfo();
    if ($err[0] === '00000' || $err[0] === '01000') {
      return true;
    }
  }
  return $affected;
}
?>
PDO::errorInfo(): http://php.net/manual/en/pdo.errorinfo.php
List of SQLSTATE Codes: http://www-01.ibm.com/support/knowledgecenter/SSGU8G_11.70.0/com.ibm.sqls.doc/ids_sqs_0809.htm

It's worth noting here, that - in addition to the hints given in docs up there - using prepare, bind and execute provides more benefits than multiply querying a statement: performance and security!
If you insert some binary data (e.g. image file) into database using INSERT INTO ... then it may boost performance of parsing your statement since it is kept small (a few bytes, only, while the image may be several MiBytes) and there is no need to escape/quote the file's binary data to become a proper string value.
And, finally and for example, if you want to get a more secure PHP application which isn't affectable by SQL injection attacks you _have to_ consider using prepare/execute on every statement containing data (like INSERTs or SELECTs with WHERE-clauses). Separating the statement code from related data using prepare, bind and execute is best method - fast and secure! You don't even need to escape/quote/format-check any data.

this function don't execute multi_query
to get it see SQLITE_EXEC comments there is an pereg function that get all queries and execute all then an return the last one

For those that want an exec that handles params like prepare/execute does. You can simulate this with another function
<?php
class Real_PDO extends PDO {
 public function execParams($sql, $params) {
  $stm = $this->prepare($sql);
  $result = false;
  if( $stm && $stm->execute($params) ) {
   $result = $stm->rowCount();
   while( $stm->fetch(PDO::FETCH_ASSOC) ) {
   }
  }
  return $result;
 }
}
?>
Remember though, if you are doing a lot of inserts, you'll want to do it the manual way, as the prepare statement will speed up when doing multiple executes(inserts). I use this so I can place all my SQL statements in one place, and have auto safe quoting against sql-injections.
If you are wondering about the fetch after, remember some databases can return data SELECT-like data from REMOVE/INSERTS. In the case of PostgreSQL, you can have it return you all records that were actually removed, or have the insert return the records after the insert/post field functions, and io trigger fire, to give you normalized data.
<?php
define("BLAH_INSERT", "INSERT INTO blah (id,data) VALUES(?,?)");
$pdo = new Real_PDO("connect string");
$data = array("1", "2");
$pdo->execParams(BLAH_INSERT, $data);
?>

I spent half a day trying to work out why I could not update my sqlite3 database from apache using the PHP PDO driver. I was getting NO error messages at all.
I could connect and select data, but not modify it.
It wasn't until I added the following line:
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
after immediately opening the database, that I got a hint of what was happening.
filename: File3
dl_count: 100
( ! ) Warning: PDO::exec() [pdo.exec.html]: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /www/htdocs/test/dl-counter/sqlite-readwrite-test.php on line 76
Call Stack
#
Time
Memory
Function
Location
1 0.0086 330120 {main}( ) ../sqlite-readwrite-test.php:0
 2 0.0273 331240 PDO->exec( ) ../sqlite-readwrite-test.php:76
 Affected Rows: ''
filename: File3
dl_count: 100
The problem was with the file permissions. As root I could read and write the database from the sqlite3 command line monitor. But Apache was unable to write the database.
Changed the permissions to 755 wwwrun:wwrun and it all works OK!
Thanks again :)

You can't use it not only with SELECT statement, but any statement that might return rows. "OPTIMIZE table" is such example (returns some rows with optimization status).
If you do, PDO will lock-up with the "Cannot execute queries while other unbuffered queries are active." nonsense.

If you do this:
<?php
$res = $dbh->query("SELECT * FROM sessions            WHERE session_id = '$p_sessID'");
$l_records = $res->fetch(PDO::FETCH_ASSOC);
if( $l_records ) {
  // ...update session-data
  $l_theQuery = "UPDATE sessions SET session_expires='$newExp', session_data='$p_sessData' WHERE session_id='$p_sessID'";
  echo $l_theQuery;
  $l_stmt = $this->db->prepare($l_theQuery);
  if ( $l_stmt ) {
   $l_rows = $l_stmt->execute();
  }
}
?>
You will get nothing.
But do this:
<?php
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
?>
Prior to the code above, you will get this:
"PDO::prepare(): SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute."
So, instead of fetch(), use fetchAll(), it will make you less insane.
Incidentally, the INSERT statement that I was issuing, if the record that I needed to update didn't yet exist, after the initial fetch() command worked perfectly.
Changing to fetchAll() fixed it.