php - 使用 PHP 将行插入 MySQL 数据库时如何确保没有现有的帖子标题？

Question

我正在使用以下函数将数据插入 MySQL 数据库。

有人可以更新它以便在标题列中已经有名称为“My Test Post”(不区分大小写)的标题时返回错误消息吗？ (我不想要任何重复的帖子)

public function insert() {
    // Does the Article object already have an ID?
    if ( !is_null( $this->id ) ) trigger_error ( "Article::insert(): Attempt to insert an Article object that already has its ID property set (to $this->id).", E_USER_ERROR );

    // Insert the Article
    $conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $sql = "INSERT INTO articles ( publicationDate, title, summary, content ) VALUES ( FROM_UNIXTIME(:publicationDate), :title, :summary, :content )";
    $st = $conn->prepare ( $sql );
    $st->bindValue( ":publicationDate", $this->publicationDate, PDO::PARAM_INT );
    $st->bindValue( ":title", $this->title, PDO::PARAM_STR );
    $st->bindValue( ":summary", $this->summary, PDO::PARAM_STR );
    $st->bindValue( ":content", $this->content, PDO::PARAM_STR );
    $st->execute();
    $this->id = $conn->lastInsertId();
    $conn = null;
}

Answer 1

$sql = "SELECT title from articles where title=:title";
    $st = $conn->prepare ( $sql );
    $st->bindValue( ":title", $this->title, PDO::PARAM_STR );
    $st->execute();
    if($st->rowCount()>0) print "error";
else{

$conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $sql = "INSERT INTO articles ( publicationDate, title, summary, content ) VALUES ( FROM_UNIXTIME(:publicationDate), :title, :summary, :content )";
    $st = $conn->prepare ( $sql );
    $st->bindValue( ":publicationDate", $this->publicationDate, PDO::PARAM_INT );
    $st->bindValue( ":title", $this->title, PDO::PARAM_STR );
    $st->bindValue( ":summary", $this->summary, PDO::PARAM_STR );
    $st->bindValue( ":content", $this->content, PDO::PARAM_STR );
    $st->execute();
    $this->id = $conn->lastInsertId();
    $conn = null;

}

不区分大小写:

$sql = "SELECT title from articles where LOWER(title)=:title";
$st->bindValue( ":title", strtolower($this->title), PDO::PARAM_STR );