The SQL USING and jOOQ onKey() shortcuts

So far, we've covered the typical JOINs that are commonly used in daily work. Before we continue with more types of JOINs, let's introduce two convenient shortcuts that are useful for expressing more concise JOINs.

SQL JOIN … USING

In certain cases, the SQL JOIN … USING clause can be a convenient alternative to the classical JOIN … ON clause. Instead of specifying a condition in the JOIN … ON clause, we enlist the JOIN … USING clause in the set of fields (columns) whose names are common to both tables – the left-hand side table and right-hand side table of a JOIN operation. In jOOQ, the USING clause is rendered via the using() method, as shown in the following example. The EMPLOYEE_NUMBER column mentioned in using() is the primary key of the EMPLOYEE table and the foreign key of the SALE table:

ctx.select(EMPLOYEE.FIRST_NAME, EMPLOYEE.LAST_NAME,    
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