With each iteration of the FORLOOP statement, its statements run, its index is either incremented or decremented, and control returns to the top of the loop. (Oracle PL/SQL Language Reference FOR LOOP Statement).
Snowflake Scripting supports FOR LOOP that loops a specified number of times. The upper and lower bounds must be INTEGER. Check more information in the Snowflake Scripting documentation.
Oracle FOR LOOP behavior can also be modified by using the statements:
CREATE OR REPLACE PROCEDURE P1ASBEGINFOR i IN1..10LOOPNULL;END LOOP;FOR i IN VAR1..VAR2LOOPNULL;END LOOP; FOR i IN REVERSE 1+2..10+5LOOPNULL;END LOOP; END;
CREATE OR REPLACE PROCEDURE PUBLIC.P1 ()RETURNS VARCHARLANGUAGE SQLEXECUTE AS CALLERAS$$BEGINFOR i IN1 TO 10LOOPNULL;END LOOP;FOR i IN VAR1 TO VAR2LOOPNULL;END LOOP;FOR i IN REVERSE 1+2 TO 10+5LOOPNULL;END LOOP;END;$$;
2. FOR LOOP with additional clauses
CREATE OR REPLACE PROCEDURE P2ASBEGINFOR i IN1..10WHILE i <=5LOOPNULL;END LOOP;FOR i IN5..15 BY 5LOOPNULL;END LOOP;END;
CREATE OR REPLACE PROCEDURE PUBLIC.P2 ()RETURNS VARCHARLANGUAGE SQLEXECUTE AS CALLERAS$$BEGIN /*** MSC-WARNING - MSCEWI3101 - FOR LOOP WITH "WHILE" CLAUSE IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING ***/
FOR i IN1 TO 10LOOPNULL;END LOOP;/*** MSC-WARNING - MSCEWI3101 - FOR LOOP WITH "BY" CLAUSE IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING ***/FOR i IN5 TO 15LOOPNULL;END LOOP;END;$$;
3. FOR LOOP with multiple conditions
CREATE OR REPLACE PROCEDURE P3ASBEGINFOR i IN REVERSE 1..3,REVERSE i+5..i+7LOOPNULL;END LOOP; END;
CREATE OR REPLACE PROCEDURE PUBLIC.P3 ()RETURNS VARCHARLANGUAGE SQLEXECUTE AS CALLERAS$$BEGIN /*** MSC-WARNING - MSCEWI3100 - FOR LOOP WITH MULTIPLE CONDITIONS IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING ***/
FOR i IN REVERSE 1 TO 3LOOPNULL;END LOOP;END;$$;
4. FOR LOOP with unsupported format
CREATE OR REPLACE PROCEDURE P3ASTYPE values_aat ISTABLEOFPLS_INTEGERINDEX BYPLS_INTEGER;l_employee_values values_aat;BEGINFORpowerIN REPEAT power*2WHILEpower<=64LOOPNULL;END LOOP;FOR i INVALUESOF l_employee_values LOOPNULL;END LOOP; END;
CREATE OR REPLACE PROCEDURE PUBLIC.P3 ()RETURNS VARCHARLANGUAGE SQLEXECUTE AS CALLERAS$$DECLARE l_employee_values VARIANT /*** MSC-WARNING - MSCEWI1055 - REFERENCED CUSTOM TYPE 'values_aat' NOT FOUND ***/;BEGIN-- ** MSC-ERROR - MSCEWI3103 - FOR LOOP FORMAT IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING **-- /*** MSC-WARNING - MSCEWI3101 - FOR LOOP WITH "WHILE" CLAUSE IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING ***/
-- FOR power IN REPEAT power*2 WHILE power <= 64 LOOP-- NULL;-- END LOOP ;-- ** MSC-ERROR - MSCEWI3103 - FOR LOOP FORMAT IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING **-- FOR i IN VALUES OF l_employee_values LOOP-- NULL;-- END LOOP ;END;$$;
Transformation for custom types is currently not supported for Snowflake Scripting.
Known Issues
1. For With Multiple Conditions
Oracle allows multiple conditions in a single FOR LOOP however, Snowflake Scripting only allows one condition per FOR LOOP. Only the first condition is migrated and the others are ignored during transformation. Check MSCEWI3100.
FOR i IN REVERSE 1..3,REVERSE i+5..i+7LOOPNULL;END LOOP;
/*** MSC-WARNING - MSCEWI3100 - FOR LOOP WITH MULTIPLE CONDITIONS IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING ***/
FOR i IN REVERSE 1 TO 3LOOPNULL;END LOOP;
2. Mutable vs Inmutable Counter Variable
Oracle allows modifying the value of the FOR LOOP variable inside the loop. The current documentation includes this functionality but Snowflake recommends avoiding this. Modifying the value of this variable may not behave correctly in Snowflake Scripting.
3. Integer vs Float number for Upper or Lower Bound
Snowflake Scripting only allows an INTEGER or an expression that evaluates to an INTEGER as a bound for the FOR LOOP condition. Floating numbers will be rounded up or down and alter the original bound. Check MSCEWI3102.
4. Oracle Unsupported Clauses
Oracle allows additional clauses to the FOR LOOP condition. Like the BY clause for a stepped increment in the condition. And the WHILE and WHEN clause for boolean expressions. These additional clauses are not supported in Snowflake Scripting and are ignored during transformation. Check MSCEWI3101.
FOR i IN5..15 BY 5LOOPNULL;END LOOP;
/*** MSC-WARNING - MSCEWI3101 - FOR LOOP WITH "BY" CLAUSE IS CURRENTLY NOT SUPPORTED BY SNOWFLAKE SCRIPTING ***/FOR i IN5 TO 15LOOPNULL;END LOOP;
5. Unsupported Formats
Oracle allows different types of conditions for a FOR LOOP. It supports boolean expressions, collections, records... However, Snowflake scripting only supports FOR LOOP with defined integers as bounds. All other formats are marked as not supported and require additional manual effort to be transformed. Check MSCEWI3103.
Related EWIs
MSCEWI3100: For Loop With Multiple Conditions Is Currently Not Supported By Snowflake Scripting.
MSCEWI3101: Specific For Loop Clause Is Currently Not Supported By Snowflake Scripting.
MSCEWI3102: For Loop With Float Number As Bound May Not Behave Correctly In Snowflake Scripting.
MSCEWI3103: For Loop Format Is Currently Not Supported By Snowflake Scripting.