Question

I have two tables in my database. The first one, [nodeActivity] has the following two columns ( primary Key = node_name )

node_name | last_updated |
          |              |
node 1    |  00:00:00    |
node 2    |  00:00:01    |

The second, table called [nodes] has the following columns ( no primary key )

node_name |  data   |  time     |
          |         |           | 
node 1    |  data1  |  00:00:01 |    
node 2    |  data2  |  00:00:01 |     
node 1    |  data3  |  00:00:02 |    
node 2    |  data5  |  00:00:02 |    
node 1    |  data6  |  00:00:03 |
node 3    |  data7  |  00:00:03 |      

I want to select only those nodes and data from [nodes], which have a corresponding entry in the [nodeActivity] table.

For example, In the above case, I want to exclude node3 and data7, as node3 is not present in [nodeActivity].
How can the above can be accomplished, in the most efficient manner possible?

Answer 1

SELECT DISTINCT n.node_name, n.data
    FROM nodes n
        INNER JOIN nodeActivity na
            ON n.node_name = na.node_name
                AND na.time = '00:00:00'