Question

我有一个社交应用，我正在尝试使用Azure Sql Server创建朋友活动源。

我想要从中选择3个表：

歌曲 -createdAt -ID -用户身份 -trackName -etc

评论 -createdAt -ID -用户身份 -songId -text

喜欢 -createdAt -ID -用户身份 -songId

我让当前用户关注的用户存储在名为＆＃39;的数组中，跟随＆＃39;。

如何从这3个表中选择40个最新项目，其中每个表中的userId位于以下数组中？

编辑：

function getActivities(userId) {

  var deferred = Q.defer();

  var follows = [];

  getFollowing(userId).then(function (results) {

     follows.push(userId);

      _.each(results, function (user) {

          follows.push(user.toUserId);

      });

      return; 

  }).then(function () {

      var stringified = "'" + follows.join("','") + "'";

      var queryString = "SELECT * FROM comments, songs, likes WHERE comments.userId IN (" + stringified + ") OR songs.userId IN (" + stringified +") OR likes.userId IN (" + stringified + ")";
      var params = [];

      return sqlQuery(queryString, params);

  }).then(function (results) {

      console.log('Activities: ', results);

      deferred.resolve(results);

  }, function (error) {

      console.log('Error: ', error.message);

      deferred.reject(error.message);

  });

  return deferred.promise;

}

Answer 1

好吧，所以我更多地挖掘了JOINS，并意识到一旦你将头包住它，它实际上是多么容易。以下是我为完成此操作所做的工作：

var queryString = "SELECT TOP 50 follows.id AS followId, follows.toUserId AS followToUserId, follows.fromUserId AS followFromUserId, comments.text AS commentText, profiles.userId, profiles.username, profiles.name, profiles.profileImage, songs.trackId, songs.trackName, songs.artistName, songs.collectionName, songs.artworkUrl100, songs.caption, songs.id AS songId, activities.id AS activityId, activities.type AS activityType, activities.objectId AS activityObjectId, activities.parentType AS activityParentType, activities.parentId AS activityParentId, activities.__createdAt AS activityCreatedAt FROM activities ";

queryString += "INNER JOIN profiles ON (profiles.userId = activities.userId) ";

queryString += "LEFT JOIN songs ON (songs.id = activities.objectId AND activities.type = 'songs') OR (songs.id = activities.parentId AND activities.parentType = 'songs') ";

queryString += "LEFT JOIN comments ON (activities.type = 'comments' AND comments.id = activities.objectId) ";

queryString += "LEFT JOIN follows ON (activities.type = 'followed' AND activities.userid = follows.fromUserId) ";

queryString += "WHERE activities.userId IN (SELECT follows.toUserId AS userId FROM follows WHERE follows.fromUserId = ? AND follows.isFollowed = 'true') ";

queryString += "ORDER BY activities.__createdAt DESC";

var params = [userId];

mssql.query(queryString, params, {

    success: function (results) {

        _.each(results, function (result) {


            //Remove columns with null or undefined values

            for (var i in result) {
              if (result[i] === null || result[i] === undefined) {
                delete result[i];
              }
            }

        });

        response.send(200, results);

    },

    error: function (error) {
        response.send(400, error.message);  
    }

});

从多个表中选择“活动”源

1 个答案: