CASE

Translation reference to convert Teradata CASE statement to Snowflake Scripting

Description

Provides conditional execution of statements based on the evaluation of the specified conditional expression or equality of two operands.

The CASE statement is different from the SQL CASE expression_,_ which returns the result of an expression.

For more information regarding Teradata CASE, check here.

-- Simple CASE
CASE operant_1
[ WHEN operant_2 THEN
     statement
     [ statement ]... ]...
[ ELSE   
     statement
     [ statement ]... ]
END CASE;

-- Searched CASE
CASE
[ WHEN conditional_expression THEN
     statement
     [ statement ]... ]...
[ ELSE   
     statement
     [ statement ]... ]
END CASE;

Sample Source Patterns

Sample auxiliar table

IN -> Teradata_01.sql
CREATE TABLE case_table(col varchar(30));

Simple Case

Teradata

IN -> Teradata_02.sql
CREATE  PROCEDURE caseExample1 ( grade NUMBER )
BEGIN
    CASE grade
        WHEN 10 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Excellent');
        WHEN 9 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Very Good');
        WHEN 8 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Good');
        WHEN 7 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Fair');
        WHEN 6 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Poor');
        ELSE INSERT INTO CASE_TABLE(COL) VALUES ('No such grade');
    END CASE;
END;

CALL caseExample1(6);
CALL caseExample1(4);
CALL caseExample1(10);
SELECT * FROM CASE_TABLE;

Snowflake Scripting

OUT -> Teradata_02.sql
CREATE OR REPLACE PROCEDURE caseExample1 (GRADE FLOAT)
RETURNS VARCHAR
LANGUAGE SQL
COMMENT = '{"origin":"sf_sc","name":"snowconvert","version":{"major":1, "minor":0},{"attributes":{"component":"teradata"}}'
EXECUTE AS CALLER
AS
$$
    BEGIN
        CASE (grade)
            WHEN 10 THEN
                INSERT INTO CASE_TABLE (COL)
                VALUES ('Excellent');
            WHEN 9 THEN
                INSERT INTO CASE_TABLE (COL)
                VALUES ('Very Good');
            WHEN 8 THEN
                INSERT INTO CASE_TABLE (COL)
                VALUES ('Good');
            WHEN 7 THEN
                INSERT INTO CASE_TABLE (COL)
                VALUES ('Fair');
            WHEN 6 THEN
                INSERT INTO CASE_TABLE (COL)
                VALUES ('Poor');
            ELSE
                INSERT INTO CASE_TABLE (COL)
                VALUES ('No such grade');
        END CASE;
    END;
$$;

CALL caseExample1(6);
CALL caseExample1(4);
CALL caseExample1(10);
SELECT * FROM CASE_TABLE;

Searched Case

Teradata

IN -> Teradata_03.sql
CREATE PROCEDURE caseExample2 ( grade NUMBER )
BEGIN
    CASE
        WHEN grade = 10 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Excellent');
        WHEN grade = 9 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Very Good');
        WHEN grade = 8 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Good');
        WHEN grade = 7 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Fair');
        WHEN grade = 6 THEN INSERT INTO CASE_TABLE(COL) VALUES ('Poor');
        ELSE INSERT INTO CASE_TABLE(COL) VALUES ('No such grade');
    END CASE;
END;

CALL caseExample2(6);
CALL caseExample2(4);
CALL caseExample2(10);
SELECT * FROM CASE_TABLE;