In what scenarios is it advisable to use the wildcard (*) in a SQL SELECT statement when fetching data from multiple tables in PHP?

Using a wildcard (*) in a SQL SELECT statement when fetching data from multiple tables in PHP is advisable when you want to retrieve all columns from all tables involved in the query. This can be useful when you need to quickly fetch and display a large amount of data without specifying each column individually. However, it is important to note that using a wildcard can result in unnecessary data retrieval and potential performance issues if not used carefully. 

<?php
// Connect to the database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}

// SQL query with wildcard (*) to fetch data from multiple tables
$sql = "SELECT * FROM table1, table2 WHERE table1.id = table2.id";

$result = $conn->query($sql);

if ($result->num_rows > 0) {
  // Output data of each row
  while($row = $result->fetch_assoc()) {
    echo "Column1: " . $row["column1"]. " - Column2: " . $row["column2"]. "<br>";
  }
} else {
  echo "0 results";
}

$conn->close();
?>

Keywords

PHP SQL SELECT statement wildcard multiple tables

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