Get a list of posts by specific category

You can also use the following query for getting the results if you have author_id, post_status and cat_id with you.

global $wpdb;

$author_id = 1;

$cat_id = 1;

$post_status="publish";

/*  Post Titles  */

$search_titles = $wpdb->get_col(        
                "SELECT DISTINCT post_title FROM $wpdb->posts
                LEFT JOIN $wpdb->term_relationships ON
                ($wpdb->posts.ID = $wpdb->term_relationships.object_id)
                LEFT JOIN $wpdb->term_taxonomy ON
                ($wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id)
                WHERE $wpdb->posts.post_status="$post_status"
                AND $wpdb->posts.post_type="post"
        AND $wpdb->posts.post_author = $author_id
                AND $wpdb->term_taxonomy.taxonomy = 'category'
                AND $wpdb->term_taxonomy.term_id = $cat_id"        
)