FOR statement

Applies to ❌ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition

When iterating over a sequence of numeric values, the FOR loop provides useful syntax sugar over the previous types of loops, including the WHILE loop, despite being functional equivalent.

An example:

-- PL/SQL

FOR i IN 1 .. 10 LOOP
  INSERT INTO t (col) VALUES (i);
END LOOP;

// All dialects
Variable<Integer> i = var("i", INTEGER);
for_(i).in(1, 10).loop(
  insertInto(T).columns(T.COL).values(i)
)

In addition to simplifying the most common case, there are also options of traversing the arguments in a reversed way, and using an additional optional step variable, for example:

-- pgplsql

FOR i IN REVERSE 10 .. 1 BY 2 LOOP
  INSERT INTO t (col) VALUES (i);
END LOOP;

// All dialects
Variable<Integer> i = var("i", INTEGER);
for_(i).inReverse(10, 1).by(2).loop(
  insertInto(T).columns(T.COL).values(i)
)

Not all dialects support the entirety of this syntax, but luckily it is easy for jOOQ to emulate in all dialects using WHILE:

-- PL/SQL
WHILE i >= 1 LOOP
  INSERT INTO t (col) VALUES (i);
  i := i - 2;
END LOOP;

Notice that for is a reserved keyword in the Java language, so the jOOQ API cannot use it as a method name. We've suffixed such conflicts with an underscore: for_().

Dialect support

This example using jOOQ:

for_(i).in(1, 10).loop(insertInto(BOOK).columns(BOOK.ID).values(i))

Translates to the following dialect specific expressions:

-- AURORA_POSTGRES, EXASOL, ORACLE, POSTGRES, YUGABYTEDB
FOR i IN 1 .. 10 LOOP
  INSERT INTO BOOK (ID)
  VALUES (i);
END LOOP

-- BIGQUERY
BEGIN
  DECLARE i int64 DEFAULT 1;
  WHILE i <= 10 DO
    INSERT INTO BOOK (ID)
    VALUES (i);
    SET i = (i + 1);
  END WHILE;
END;

-- DB2
BEGIN
  DECLARE i integer;
  SET i = 1;
  WHILE i <= 10 DO
    INSERT INTO BOOK (ID)
    VALUES (i);
    SET i = (i + 1);
  END WHILE;
END;

-- FIREBIRD

DECLARE i integer DEFAULT 1;
WHILE (:i <= 10) DO BEGIN
  INSERT INTO BOOK (ID)
  VALUES (:i);
  :i = (:i + 1);
END

-- H2
for (Integer i = 1; i <= 10; i++) {
  try (PreparedStatement s = c.prepareStatement(
    "INSERT INTO BOOK (ID)\n" +
    "VALUES (?)"
  )) {
    s.setObject(1, i);
    s.execute();
  }
}

-- HANA
BEGIN
  DECLARE i integer;
  FOR i IN 1 .. 10 DO
    INSERT INTO BOOK (ID)
    VALUES (i);
  END FOR;
END;

-- HSQLDB
BEGIN ATOMIC
  DECLARE i int;
  SET i = 1;
  WHILE i <= 10 DO
    INSERT INTO BOOK (ID)
    VALUES (i);
    SET i = (i + 1);
  END WHILE;
END;

-- INFORMIX
BEGIN
  DEFINE i integer;
  LET i = 1;
  FOR i IN (1 TO 10) LOOP
    INSERT INTO BOOK (ID)
    VALUES (i);
  END LOOP;
END;

-- MARIADB
FOR i IN 1 .. 10 DO
  INSERT INTO BOOK (ID)
  VALUES (i);
END FOR

-- MYSQL
BEGIN
  DECLARE i int;
  SET i = 1;
  WHILE i <= 10 DO
    INSERT INTO BOOK (ID)
    VALUES (i);
    SET i = (i + 1);
  END WHILE;
END;

-- SQLDATAWAREHOUSE
BEGIN
  DECLARE @i int DEFAULT 1;
  WHILE @i <= 10 BEGIN
    INSERT INTO BOOK (ID)
    SELECT @i;
    SET @i = (@i + 1);
  END;
END;

-- SQLSERVER
BEGIN
  DECLARE @i int = 1;
  WHILE @i <= 10 BEGIN
    INSERT INTO BOOK (ID)
    VALUES (@i);
    SET @i = (@i + 1);
  END;
END;

-- ACCESS, ASE, AURORA_MYSQL, COCKROACHDB, DERBY, MEMSQL, REDSHIFT, SNOWFLAKE, SQLITE, SYBASE, TERADATA, VERTICA
/* UNSUPPORTED */

(These are currently generated with jOOQ 3.17, see #10141), or translate your own on our website

The jOOQ User Manual : SQL building : Procedural statements : FOR statement

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