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 1. Introduction
 2. A Simple Query
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 5. Multiple Tables
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 11. Conclusion

Practice Using Joins

Write queries to answer the astronomy questions in Practice 5 and 6. Use the Schema Browser when you need it. (Note: these queries will probably take the full 90 seconds to execute... just let them run until you see the results.)

Practice 5. How can you look up image data, plates and spectra of moderately bright nearby galaxies?

Write a query to find galaxies for which we have spectra that have g magnitude between 17 and 17.4 and redshift less than 0.05. For each galaxy, retrieve the object ID, the five magnitudes (u,g,r,i,z), the redshift, the plate/MJD number, and the fiber number.

Practice 6. What types (templates) of quasars have high redshifts?

Write a query to find the template number matched to all high redshift quasars (redshift greater than 2.5).
HINT: template number is in the Cross-Correlation Redshifts table. Retrieve the objects' ra, dec, u, g, r, i, z, redshift, and tempno.

Answers


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Enter your SQL query in the text box. The query is limited to 90 seconds and 1,000 rows.