title: Try to get average value from Android Room Persistence Library with dynamic conditions
body: <p>I am trying to get average value if two conditions using Android Room Persistence Library, my entity looks like this:</p>
  
  <pre><code>public class FinishedTask {
      private static final String TASK_NAME_COLUMN = "taskName";
      private static final String DEPARTMENT_NAME_COLUMN = "departmentName";
      private static final String EMPLOYEE_NAME_COLUMN = "employeeName";
      private static final String TIME_UNTIL_DOME_NAME_COLUMN = "timeUntilDoneName";
      private static final String SAVED_DATE_NAME_COLUMN = "savedDateName";
  
      @PrimaryKey(autoGenerate = true)
      @ColumnInfo(name = "id")
      private long id = 0;
  
      @ColumnInfo(name = "passedMilliseconds")
      private long passedMilliseconds = 0;
  
      @ColumnInfo(name = TASK_NAME_COLUMN)
      private String  taskName = TASK_NAME_COLUMN;
  
      @ColumnInfo(name = DEPARTMENT_NAME_COLUMN)
      private String departmentName = DEPARTMENT_NAME_COLUMN;
  
      @ColumnInfo(name = EMPLOYEE_NAME_COLUMN)
      private String employeeName = EMPLOYEE_NAME_COLUMN;
  
      @ColumnInfo(name = TIME_UNTIL_DOME_NAME_COLUMN)
      private long timeUntilDone = 0;
  
  
      @ColumnInfo(name = SAVED_DATE_NAME_COLUMN)
      private long savedDate = 0;
  
      public FinishedTask(){}
  }
  </code></pre>
  
  <p>My Query looks like this:</p>
  
  <pre><code>@Query("SELECT AVG(timeUntilDoneName) FROM finishedTasks WHERE :column1=:value1 AND :column2=:value2")
  Single&lt;Long&gt; getAverageTime(String column1, String value1, String column2, String value2);
  </code></pre>
  
  <p>And I got error: </p>
  
  <blockquote>
    <p>Query returned empty result set: SELECT AVG(timeUntilDoneName) FROM finishedTasks WHERE ?=? AND ?=?</p>
  </blockquote>
  
  <p>When I change query to:</p>
  
  <pre><code>@Query("SELECT AVG(timeUntilDoneName) FROM finishedTasks WHERE taskName=:value1 AND :departmentName=:value2")
  Single&lt;Long&gt; getAverageTime(String value1, String value2);
  </code></pre>
  
  <p>Everything works fine and as expected. What am I doing wrong?</p>