Function and usage of get_posts_by_author_sql() in wordpress

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    2024-01-07T15:35:54+00:00

    The get_posts_by_author_sql() function in WordPress is a versatile function that helps to retrieve SQL code for querying posts based on various criteria, including the capability of the user, the author of the posts, and the type of posts. Here's a detailed explanation and a sample usage of this function:

    Function:

    get_posts_by_author_sql( string|string[] $post_type, bool $full = true, int $post_author = null, bool $public_only = false ): string

    Description:

    This function is designed to generate SQL code for querying posts in WordPress. It takes into account the capabilities of the current user, the author of the posts, and the types of posts to be retrieved. It's particularly useful for custom queries where you need to filter posts by their author and type.

    Parameters:

    1. $post_type (string|string[]): This is a required parameter. You can pass either a single post type as a string or an array of post types. Post types are basically different types of content in WordPress, like 'post', 'page', etc.

    2. $full (bool): This optional parameter determines the format of the returned SQL code. If set to true, the function returns a full WHERE statement. If false, it returns just an 'AND' term. The default value is true.

    3. $post_author (int): An optional parameter that allows you to query posts from a specific author by their ID. The default is null, which means it doesn't filter by author.

    4. $public_only (bool): This optional parameter, when set to true, limits the query to only public posts. It skips capability checks for the current user. The default is false, meaning it includes private posts based on the user's capabilities.

    Return:

    The function returns a string containing the SQL WHERE clause that can be used in a custom query.

    Sample Usage:

    // Example: Get SQL for querying posts of type 'post' and 'page' by author ID 10
    $post_types = array('post', 'page');
    $author_id = 10;
    $sql = get_posts_by_author_sql($post_types, true, $author_id);
    
    // Use the returned SQL to create a custom query
    global $wpdb;
    $query = "SELECT * FROM $wpdb->posts WHERE " . $sql;
    $posts = $wpdb->get_results($query);
    

    In this example, the get_posts_by_author_sql() function is used to generate SQL for a custom query that fetches posts of type 'post' and 'page' authored by the user with ID 10. The returned SQL is then combined with a SELECT statement to fetch the desired posts from the database.

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