FOR

A FOR loop allows repeating a sequence of steps a defined number of times. The FOR statement is only valid within a scripting block.

See also BREAK, CONTINUE.

Syntax | FOR number of iterations

Executes a FOR loop for a specific number of iterations:

FOR counter_var IN [REVERSE] start_value TO end_value DO 
    statement;
    [statement; ... ]
END FOR [label] ;

or 

FOR counter_var IN [REVERSE] start_value TO end_value LOOP
    statement;
    [statement; ... ]
END LOOP [label] ;

Arguments

counter_var: Variable name.

• The name counter_var is only valid within the scope of the FOR loop.
• If a variable with the same name is already declared outside the loop, the outer and loop variables are separate. Inside the loop, references to counter_var resolve to the loop-local variable.
• Modifying the value of counter_var inside the loop is technically possible, but not recommended.

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start_value: The starting value of counter_var, either an INTEGER or an expression that results in an INTEGER.

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end_value: The ending value of counter_var, either an INTEGER or an expression that results in an INTEGER. end_value must be greater than or equal to start_value. If end_value < start_value, the loop runs 0 times, even if the REVERSE keyword is used.

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statement: One (or more) statements of the following types:

• A single SQL statement (including CALL).
• A control flow statement (e.g. loop or conditional).
• A nested block.

---

label (optional): A label defines a jump target for BREAK or CONTINUE statements.

Usage Notes

• The iteration range includes the end point. Example: FOR i IN 1 TO 10 will execute with i = 10 on the last loop.
• Using the REVERSE keyword makes the loop run “backwards”, including the start value.
• A loop can contain multiple statements. Optionally, a BEGIN … END block can be used to enclose them.
• When using the FOR ... DO form, use END FOR to close the loop. When using FOR ... LOOP, use END LOOP.

Example 1 | FOR with Number of Iterations

CREATE PROCEDURE mkw_doku.for_with_count(count_iter INTEGER)
RETURNS INTEGER
AS
    DECLARE
        count INTEGER DEFAULT 0;
    BEGIN
        FOR i IN 1 TO :count_iter DO
            LET count := :count + 1;
        END FOR;
        RETURN :count;
    END;

CALL mkw_doku.for_with_count(3);

Procedure 'mkw_doku.for_with_count' was successfully executed

Example 2 | FOR with REVERSE

CREATE PROCEDURE mkw_doku.for_with_reverse(count_iter INTEGER)
RETURNS STRING
AS
    DECLARE
        count_text STRING DEFAULT '';
    BEGIN
        FOR i IN REVERSE 1 TO :count_iter DO
            count_text := :count_text || ' ' || :i;
        END FOR;
        RETURN :count_text;
    END;

CALL mkw_doku.for_with_reverse(3);

Procedure 'mkw_doku.for_with_reverse' was successfully executed