PHP PDOStatement::bindParam() Method: Usage and Examples

Binds a variable by reference to an input placeholder.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Binds a variable by reference to an input placeholder.

Syntax and Return Value

PDOStatement::bindParam(Parameter #0 [ <required> string|int $param ], Parameter #1 [ <required> mixed &$var ], Parameter #2 [ <optional> int $type = PDO::PARAM_STR ], Parameter #3 [ <optional> int $maxLength = 0 ], Parameter #4 [ <optional> mixed $driverOptions = null ]): mixed

The return value and exceptional cases depend on the call described here: The variable is read at execute time; do not pass temporary expressions as references.

Example 1: Basic Use

The statement has a real query and result set; database-specific metadata and statement options may be unsupported.

<?php
$pdo = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$pdo->exec('CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT NOT NULL, price INTEGER NOT NULL, active INTEGER)');
$pdo->exec("INSERT INTO products (id,name,price,active) VALUES (1,'Desk',120,1),(2,'Lamp',35,1),(3,'Chair',85,0)");
$stmt = $pdo->prepare("SELECT name FROM products WHERE id = :id");
$id = 1;
$stmt->bindParam(":id", $id, PDO::PARAM_INT);
$stmt->execute();
echo $stmt->fetchColumn();

Example 2: A Second Scenario

The statement has a real query and result set; database-specific metadata and statement options may be unsupported.

<?php
$pdo = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$pdo->exec('CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT NOT NULL, price INTEGER NOT NULL, active INTEGER)');
$pdo->exec("INSERT INTO products (id,name,price,active) VALUES (1,'Desk',120,1),(2,'Lamp',35,1),(3,'Chair',85,0)");
$stmt = $pdo->prepare("SELECT name FROM products WHERE id = :id");
$id = 2;
$stmt->bindParam(":id", $id, PDO::PARAM_INT);
$stmt->execute();
echo $stmt->fetchColumn();

Example 3: Practical Checks

The statement has a real query and result set; database-specific metadata and statement options may be unsupported.

<?php
$pdo = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$pdo->exec('CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT NOT NULL, price INTEGER NOT NULL, active INTEGER)');
$pdo->exec("INSERT INTO products (id,name,price,active) VALUES (1,'Desk',120,1),(2,'Lamp',35,1),(3,'Chair',85,0)");
$stmt = $pdo->prepare("SELECT name FROM products WHERE id = :id");
$id = 3;
$stmt->bindParam(":id", $id, PDO::PARAM_INT);
$stmt->execute();
echo $stmt->fetchColumn();

Important Behavior and Edge Cases

The variable is read at execute time; do not pass temporary expressions as references.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Binds a variable by reference to an input placeholder.
• The variable is read at execute time; do not pass temporary expressions as references.
• bindValue captures a value immediately instead of following later variable changes.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.