title: How to join two Tables which have no unique ID
body: <p>I am trying to Left join Table 1 to table 2</p>
  
  <pre><code>Table1          Table2  
  ID  Data        ID  Data2
  1   r           1   q
  2   t           1   a
  3   z           2   x
  1   u           3   c
  </code></pre>
  
  <p>After i have left joined this two Tables i would like get something like this</p>
  
  <pre><code>  Table1+2      
  ID  Data    Data2
  1   r        a
  2   t        x
  3   z        c
  1   u        q
  </code></pre>
  
  <p>and NOT    </p>
  
  <pre><code>  Table1+2      
  ID  Data    Data2
  1   r        q
  2   t        x
  3   z        c
  1   u        q
  </code></pre>
  
  <p>and my question is: is there any possibility to tell table 2 that if u have used something for table 1, dont use it and give me next value. do i have to make it im T-SQL or to and new column where i can list if this id exists then write 2 if not 1(Number data). How can i solve this problem?
  Ty u in advance.  </p>