Introduced
Today, php5.1.* and php5.2.* are found to be different when the database precompiled code executes.
Pre-compilation Benefits
1. Use placeholders to avoid literal input of data into SQL. Automatically handles the escaping of characters such as quotes and backslashes-increasing security.
2. Pre-"prepare" a statement and then bind different values at each execution to achieve the purpose of reuse. -often used for statements that are executed more than once.
3. Readability is strong.
Code
The database connection code is the same.
Copy CodeThe code is as follows:
$protol = ' mysql:host=localhost;dbname=test ';
$username = ' Monty ';
$passwd = ' 0818 ';
$DBH = new PDO ($protol, $username, $passwd);
Here are some tests. Note the SQL and for or foreach statements inside!
Test 1 (Bind with a key value)
Copy CodeThe code is as follows:
$stmt = $dbh->prepare (' select * from t1 where Name=:name ');
$params = Array ();
$params [' name '] = ' Rentao ';
foreach ($params as $k = = $v) {
$stmt->bindparam ($k, $v);
}
$stmt->execute ();
$item = Array ();
while ($row = $stmt->fetch (PDO::FETCH_ASSOC)) {
Var_dump ($row);
}
$stmt = null;
$DBH = null;
Conclusion:
| PHP 5.1.* |
PHP 5.2.* |
| Perform normal |
Perform normal |
| $params [' name '] = ' Rentao ' and $params[': Name ']= ' Rentao ' Both can be executed, stating that there is no ":" Limit. |
Test 2 (numeric subscript to bind, but binding starting parameter is 1)--": Key" cannot be bound with numeric subscript on php5.2.*
Copy CodeThe code is as follows:
$stmt = $dbh->prepare (' select * from t1 where name=:name limit 2 ');
$params = Array ();
$params [] = ' rentao ';//Add No ":" to execute successfully
For ($i =0, $iLen = count ($params); $i < $iLen; $i + +) {
$k = $i +1;
$stmt->bindparam ($k, $params [$i]);
}
echo "here1\n";
$stmt->execute ();
echo "here2\n";
$item = Array ();
while ($row = $stmt->fetch (PDO::FETCH_ASSOC)) {
Var_dump ($row);
}
$stmt = null;
$DBH = null;
Conclusion:
| PHP 5.1.* |
PHP 5.2.* |
| Perform normal |
Error: "PHP warning:pdostatement::execute (): sqlstate[hy093]: Invalid parameter number:parameter was not defined" |
| If you change the ": Name" to "?", then the two versions will go smoothly. |
| Two symbols cannot be used at the same time. such as SELECT * from T2 where name=? limit :p age |
Test 3 (Limit binding: page)
Copy CodeThe code is as follows: $stmt = $dbh->prepare (' select * from T2 where name=:name limit:p age ');
$params = Array ();
$params [' name '] = ' rentao ';//Add ":" to execute successfully
$params [' page '] = 2;
foreach ($params as $k = = $v) {
$stmt->bindparam ($k, $v);
}
$stmt->execute ();
echo "here1\n";
$item = Array ();
while ($row = $stmt->fetch (PDO::FETCH_ASSOC)) {
Var_dump ($row);
}
echo "here2\n";
$stmt = null;
$DBH = null;
Conclusion:
| PHP 5.1.* |
PHP 5.2.* |
| Process is in a wait state when executed to $stmt->execute () |
Normal execution: No results are printed |
Test 4 (pre-compile at limit: page)--use "? "Mechanism runs
Copy CodeThe code is as follows:
$stmt = $dbh->prepare (' select * from T2 where name=? ');
$params = Array ();
$params [] = ' Rentao ';
$params [] = 2;
For ($i =0, $iLen = count ($params); $i < $iLen; $i + +) {
$k = $i +1;
$stmt->bindparam ($k, $params [$i]);
}
$stmt->execute ();
$item = Array ();
while ($row = $stmt->fetch (PDO::FETCH_ASSOC)) {
Var_dump ($row);
}
$stmt = null;
$DBH = null;
| PHP 5.1.* |
PHP 5.2.* |
| Perform normal |
Normal execution: No results are printed |
Test 5---ORDER BY)
| PHP 5.1.* |
PHP 5.2.* |
| Results are printed but not ordered by order |
Normal execution: No results are printed |
Summary
PHP when using PDO to do database pre-compilation operations, try to avoid using limit, order by, the group by do pre-compile processing. Binding variables We try to use a uniform standard, or else we use "? ", otherwise use": Key ".
Useful command, I tested it in php5.1.*, I passed the file to the php5.2.* server via SCP
Copy CodeThe code is as follows: scp-p9888 index.php Rentao@192.168.10.4:/home/rentao
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