title: SQL query from three tables, using the results from the first table
body: <p>I am having trouble with queries from multiple tables. My platform is SQL. The first two columns of each table (ID, Tag) are related to each other. I am trying to select data from table2 and table3 using the results from table1.</p>
  
  <p><img src="https://i.stack.imgur.com/gzEll.jpg" alt="Table1.ID, Tag, Top Weight, Bottom Weight, Total Weight">
  <img src="https://i.stack.imgur.com/gkPi3.jpg" alt="Table2.ID, Tag, Color, Shade, Tint, Transparancy">
  <img src="https://i.stack.imgur.com/6FvQP.jpg" alt="Table3.ID, Tag, Sequence, Length, Width, Height"></p>
  
  <p>Table1 is used to determine the ID and Tag. The combination of ID and Tag is unique for this table. There are no null values in table1. In this example, I will search for the ID and Tag using the Top Weight and Bottom Weight. However, any number of criteria can be used to find the ID and Tag. </p>
  
  <pre><code>SELECT ID, Tag FROM table1 WHERE Top Weight = '22' AND Bottom Weight = '44'
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/5d3fj.jpg" alt="Table1 query results"></p>
  
  <p>I would like to take the ID and Tag results from table1, and use them for my table2 and table3 queries. For table2, the combination of the first two columns (ID, Tag) is unique. I would like to select Color, Shade, and Tint from this table. There can be null values for these columns. For table3, the combination of the first three columns (ID, Tag, Sequence) is unique. I would like to select Sequence, Length, and Width from this table. These columns can also have null values.  </p>
  
  <p>Is it possible to combine all three tables into a single query, and use the results of the first table to get the results of the second and third table? The example tables are only 14 rows, but in reality, there are tens of thousands of rows – so performance is critical (when is it not?). I look forward to your response, thanks.</p>