How to Properly Bind LIKE Operators with Special Characters in PDO?

Using LIKE Operators with PDO Bindings

Binding LIKE values with PDO can be confusing due to the use of special characters ('%' and '_') in the matching pattern. In this specific query:

SELECT wrd FROM tablename WHERE wrd LIKE '$partial%'

There are several options for binding the partial string '$partial%':

• Option 1:

SELECT wrd FROM tablename WHERE wrd LIKE ':partial%'

Here, the parameter ':partial' is bound to '$partial="somet"', appending the wildcard '%' to the end of the string.

• Option 2:

SELECT wrd FROM tablename WHERE wrd LIKE ':partial'

In this case, the parameter ':partial' is bound to '$partial="somet%"', which includes the wildcard character in the bound value.

• Option 3 (Alternative):

SELECT wrd FROM tablename WHERE wrd LIKE CONCAT(:partial, '%')

This option allows you to perform the string concatenation within the MySQL query, rather than in the PHP code.

Handling Special Characters

If the partial string contains special characters like '%', '_' or '', more complex methods are required to escape them properly. Here's an example:

$stmt = $db->prepare("SELECT wrd FROM tablename WHERE wrd LIKE :term ESCAPE '+'");
$escaped = str_replace(array('+', '%', '_'), array('++', '+%', '+_'), $var);
$stmt->bindParam(':term', $escaped);

In this code, the special characters are replaced with escape sequences (' ', ' %' and ' _') to ensure they are interpreted correctly by MySQL.

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