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LAG
Applies to ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
The LAG window function allows for getting the value of an expression evaluated on the previous row, or the nth previous row if an offset is given.
SELECT ID, lag(ID) OVER (ORDER BY ID), lag(ID, 2) OVER (ORDER BY ID), lag(ID, 2, -1) OVER (ORDER BY ID) FROM BOOK;
create.select(
BOOK.ID,
lag(BOOK.ID).over(orderBy(BOOK.ID)),
lag(BOOK.ID, 2).over(orderBy(BOOK.ID)),
lag(BOOK.ID, 2, -1).over(orderBy(BOOK.ID)))
.from(BOOK)
.fetch();
Producing:
+----+------+------+------+ | id | lag | lag | lag | +----+------+------+------+ | 1 | | | -1 | | 2 | 1 | | -1 | | 3 | 2 | 1 | 1 | | 4 | 3 | 2 | 2 | +----+------+------+------+
- The window frame clause has no effect on
LAG. -
LAGsupports the optional NULL treatment clause.
Dialect support
This example using jOOQ:
lag(BOOK.ID).over(orderBy(BOOK.ID))
Translates to the following dialect specific expressions:
-- AURORA_POSTGRES, BIGQUERY, COCKROACHDB, DB2, DUCKDB, EXASOL, FIREBIRD, H2, HANA, INFORMIX, MARIADB, MEMSQL, MYSQL, -- ORACLE, POSTGRES, REDSHIFT, SNOWFLAKE, SQLDATAWAREHOUSE, SQLITE, SQLSERVER, TERADATA, TRINO, VERTICA, YUGABYTEDB lag(BOOK.ID) OVER (ORDER BY BOOK.ID) -- ACCESS, ASE, AURORA_MYSQL, DERBY, HSQLDB, SYBASE /* UNSUPPORTED */
(These are currently generated with jOOQ 3.19, see #10141), or translate your own on our website
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