Check if column exists, if not, add in MySQL through PHP

Question

I\'m using the following code to check if the column exists, and if it doesn\'t, add it:

mysql_query(\"select $column from $table\") or mysql_query(\"alter t         


        

Answer 1

You can change your SQL to...

//THIS IS BETTER BUT DONT USE THIS
$qry = "ALTER IGNORE TABLE {$table} ADD {$column} VARCHAR(20);"

Instead use PHP PDO or MySQLi with prepared statements. Instead of that legacy horror with concatinated unescaped strings.

MySQLi Solution:

$mysqli = new mysqli($cfg->host, $cfg->user, $cfg->password, $cfg->db);

if ($mysqli->connect_errno) {
    echo 'Connect failed: ', $mysqli->connect_error, '" }';
    exit();
}

if ($stmt = $mysqli->prepare("ALTER IGNORE TABLE ? ADD ? VARCHAR(20);")) {
    $stmt->bind_param("ss", $table, $column);
    $stmt->execute();
    $stmt->close();
}
$mysqli->close();

Answer 2

For msqli users

$result = $mysqli->query("SHOW COLUMNS FROM tablename LIKE 'keyword");
$exists = (mysqli_num_rows($result))?TRUE:FALSE;

Answer 3

$r=mysql_num_rows(mysql_query("SHOW columns from '".$table."' where field='".$column."'"));
if ($r==0){
    mysql_query("alter table $table add $column varchar (20)");
}