WHILE (Snowflake Scripting)

A WHILE loop iterates while a specified condition is true.

For more information on loops, see Working with loops.

Note

This Snowflake Scripting construct is valid only within a Snowflake Scripting block.

See also:

BREAK, CONTINUE

Syntax

WHILE ( <condition> ) { DO | LOOP }
    <statement>;
    [ <statement>; ... ]
END { WHILE | LOOP } [ <label> ] ;
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Where:

condition

An expression that evaluates to a BOOLEAN.

statement

A statement can be any of the following:

  • A single SQL statement (including CALL).

  • A control-flow statement (for example, a looping or branching statement).

  • A nested block.

label

An optional label. Such a label can be a jump target for a BREAK or CONTINUE statement. A label must follow the naming rules for Object identifiers.

Usage notes

  • Put parentheses around the condition in the WHILE. For example: WHILE ( <condition> ).

  • If the condition never evaluates to FALSE, and the loop doesn’t contain a BREAK (Snowflake Scripting) command (or equivalent), then the loop will run and consume credits indefinitely.

  • If the condition is NULL, then it is treated as FALSE.

  • A loop can contain multiple statements. You can use, but are not required to use, a BEGIN … END block to contain those statements.

  • Pair the keyword DO with END WHILE, and pair the keyword LOOP with END LOOP. For example:

    WHILE (...) DO
    ...
END WHILE;

WHILE (...) LOOP
    ...
END LOOP;
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Examples

This example uses a loop to calculate a power of 2. The counter variable is the loop counter. The power_of_2 variable stores the most recent power of 2 that was calculated. (This is an inefficient solution, but it demonstrates looping.)

CREATE PROCEDURE power_of_2()
RETURNS NUMBER(8, 0)
LANGUAGE SQL
AS
$$
DECLARE
  counter NUMBER(8, 0);      -- Loop counter.
  power_of_2 NUMBER(8, 0);   -- Stores the most recent power of 2 that we calculated.
BEGIN
  counter := 1;
  power_of_2 := 1;
  WHILE (counter <= 8) DO
    power_of_2 := power_of_2 * 2;
    counter := counter + 1;
  END WHILE;
  RETURN power_of_2;
END;
$$
;
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Call the stored procedure:

CALL power_of_2();
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+------------+
| POWER_OF_2 |
|------------|
|        256 |
+------------+

This example uses a loop and the DATEADD function to add a day to a date until the condition is met.

EXECUTE IMMEDIATE $$
BEGIN
  LET mydate := '2024-05-08';
  WHILE (mydate < '2024-05-20') DO
    mydate := DATEADD(day, 1, mydate);
  END WHILE;
  RETURN mydate;
END;
$$
;
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+-------------------------+
| anonymous block         |
|-------------------------|
| 2024-05-20 00:00:00.000 |
+-------------------------+

For more examples, see WHILE loop.

Language: English