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DECODE
Applies to ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
Some SQL dialects, including Db2, H2, Oracle know a more succinct, but maybe less readable DECODE() function with a variable number of arguments. This function works like a NULL safe CASE expression. jOOQ supports the DECODE() function and emulates it using CASE expressions in all dialects that do not have native support:
SELECT
-- Oracle:
DECODE(FIRST_NAME, 'Paulo', 'brazilian',
'George', 'english',
'unknown'),
-- Other SQL dialects
CASE
WHEN FIRST_NAME IS NOT DISTINCT FROM 'Paulo' THEN 'brazilian'
WHEN FIRST_NAME IS NOT DISTINCT FROM 'George' THEN 'english'
ELSE 'unknown'
END
FROM AUTHOR
// Use the Oracle-style DECODE() function with jOOQ. // Note, that you will not be able to rely on type-safety decode( AUTHOR.FIRST_NAME, "Paulo", "brazilian", "George", "english", "unknown" );
See the DISTINCT predicate for details about the NULL safe semantics.
Dialect support
This example using jOOQ:
decode(AUTHOR.FIRST_NAME, "Paulo", "BR", "George", "EN", "unknown")
Translates to the following dialect specific expressions:
-- ASE, SQLDATAWAREHOUSE
CASE
WHEN EXISTS (
SELECT AUTHOR.FIRST_NAME x
INTERSECT
SELECT 'Paulo' x
) THEN 'BR'
WHEN EXISTS (
SELECT AUTHOR.FIRST_NAME x
INTERSECT
SELECT 'George' x
) THEN 'EN'
ELSE 'unknown'
END
-- AURORA_MYSQL, MYSQL
CASE
WHEN (AUTHOR.FIRST_NAME <=> 'Paulo') THEN 'BR'
WHEN (AUTHOR.FIRST_NAME <=> 'George') THEN 'EN'
ELSE 'unknown'
END
-- AURORA_POSTGRES, BIGQUERY, COCKROACHDB, DUCKDB, FIREBIRD, HSQLDB, POSTGRES, SNOWFLAKE, SQLSERVER, TRINO, YUGABYTEDB
CASE
WHEN AUTHOR.FIRST_NAME IS NOT DISTINCT FROM 'Paulo' THEN 'BR'
WHEN AUTHOR.FIRST_NAME IS NOT DISTINCT FROM 'George' THEN 'EN'
ELSE 'unknown'
END
-- DB2, EXASOL, H2, INFORMIX, MEMSQL, ORACLE, TERADATA, VERTICA
decode(
AUTHOR.FIRST_NAME,
'Paulo',
'BR',
'George',
'EN',
'unknown'
)
-- DERBY
CASE
WHEN EXISTS (
SELECT AUTHOR.FIRST_NAME x
FROM SYSIBM.SYSDUMMY1
INTERSECT
SELECT 'Paulo' x
FROM SYSIBM.SYSDUMMY1
) THEN 'BR'
WHEN EXISTS (
SELECT AUTHOR.FIRST_NAME x
FROM SYSIBM.SYSDUMMY1
INTERSECT
SELECT 'George' x
FROM SYSIBM.SYSDUMMY1
) THEN 'EN'
ELSE 'unknown'
END
-- HANA
map(
AUTHOR.FIRST_NAME,
'Paulo',
'BR',
'George',
'EN',
'unknown'
)
-- MARIADB
decode_oracle(
AUTHOR.FIRST_NAME,
'Paulo',
'BR',
'George',
'EN',
'unknown'
)
-- REDSHIFT
CASE
WHEN NOT (AUTHOR.FIRST_NAME IS DISTINCT FROM 'Paulo') THEN 'BR'
WHEN NOT (AUTHOR.FIRST_NAME IS DISTINCT FROM 'George') THEN 'EN'
ELSE 'unknown'
END
-- SQLITE
CASE
WHEN (AUTHOR.FIRST_NAME IS 'Paulo') THEN 'BR'
WHEN (AUTHOR.FIRST_NAME IS 'George') THEN 'EN'
ELSE 'unknown'
END
-- SYBASE
CASE
WHEN EXISTS (
SELECT AUTHOR.FIRST_NAME x
FROM SYS.DUMMY
INTERSECT
SELECT 'Paulo' x
FROM SYS.DUMMY
) THEN 'BR'
WHEN EXISTS (
SELECT AUTHOR.FIRST_NAME x
FROM SYS.DUMMY
INTERSECT
SELECT 'George' x
FROM SYS.DUMMY
) THEN 'EN'
ELSE 'unknown'
END
-- ACCESS
/* UNSUPPORTED */
(These are currently generated with jOOQ 3.19, see #10141), or translate your own on our website
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