Pre-joining

DocMusherDocMusher Member Posts: 333 Unicorn
edited November 2018 in Help
Hi,
How can I pre-join more than 2 tables in read database query?
Is somebody using a psql visual query builder within RM?
Sven

Answers

  • JEdwardJEdward RapidMiner Certified Analyst, RapidMiner Certified Expert, Member Posts: 578 Unicorn
    If you're using SQL the format of the join code is pretty straightforward

    SELECT *  FROM /* This selects all columns */
    table1
    INNER JOIN table2  /* Use LEFT JOIN or RIGHT JOIN if needed.
    ON table1.key1 = table2.key2  /* here you put in your key joins, use AND or OR to separate out different join rules.
    INNER JOIN table3  /* Use LEFT JOIN or RIGHT JOIN if needed.
    ON table1.key1 = table3.key2  /* You can also join to table2 if needed.


    This is standard SQL so the same query would work on Oracle, SQL Server, MySQL, PostgreSQL as you choose. 
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