This documentation is for the unreleased development version of jOOQ. Click on the above version links to get this documentation for a supported version of jOOQ.
Applies to ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
INNER JOIN or just
JOIN works like a CROSS JOIN, but adds a predicate of some sort filtering out unwanted combinations. This is the most popular way to join tables, as we hardly ever want to combine arbitrary rows from both tables, but the ones that have some relationship with each other, e.g. a
FOREIGN KEY reference match.
SELECT * FROM AUTHOR JOIN BOOK ON BOOK.AUTHOR_ID = AUTHOR.ID
create.select() .from(AUTHOR) .join(BOOK).on(BOOK.AUTHOR_ID.eq(AUTHOR.ID)) .fetch();
The above query will return all authors and their books. True to the nature of an
INNER JOIN, authors without books are excluded as well as books without authors (if the
FOREIGN KEY is optional).
The result might look like this:
+------------+-----------+--------------+ | FIRST_NAME | LAST_NAME | TITLE | +------------+-----------+--------------+ | George | Orwell | 1984 | | George | Orwell | Animal Farm | | Paulo | Coelho | O Alquimista | | Paulo | Coelho | Brida | +------------+-----------+--------------+
In the example, we're using the ON clause to form the
JOIN predicate, but other options will be discussed in later sections as well.
INNER keyword is optional both in SQL and in jOOQ, and does not affect the query semantics at all.
This example using jOOQ:
Translates to the following dialect specific expressions:
-- ACCESS SELECT BOOK.ID, AUTHOR.ID FROM BOOK INNER JOIN AUTHOR ON BOOK.AUTHOR_ID = AUTHOR.ID -- ASE, AURORA_MYSQL, AURORA_POSTGRES, BIGQUERY, COCKROACHDB, DB2, DERBY, DUCKDB, EXASOL, FIREBIRD, H2, HANA, HSQLDB, -- INFORMIX, MARIADB, MEMSQL, MYSQL, ORACLE, POSTGRES, REDSHIFT, SNOWFLAKE, SQLDATAWAREHOUSE, SQLITE, SQLSERVER, SYBASE, -- TERADATA, TRINO, VERTICA, YUGABYTEDB SELECT BOOK.ID, AUTHOR.ID FROM BOOK JOIN AUTHOR ON BOOK.AUTHOR_ID = AUTHOR.ID