Teradata 存储过程变量

Question

I'm trying to create a stored procedure to create all possible combination of a table with itself. For now, I got this code, but it produces the following error:

Syntax error: expected something between the word 'A' and the integer '2'

Code:

CREATE MULTISET TABLE PRUEBA
(
    CAMPO VARCHAR(10)
);

INSERT INTO PRUEBA VALUES('A');
INSERT INTO PRUEBA VALUES('B');
INSERT INTO PRUEBA VALUES('C');

REPLACE PROCEDURE TEST()

BEGIN
   DECLARE a VARCHAR(255);
   DECLARE b VARCHAR(225);
   DECLARE qry VARCHAR(255);
   DECLARE i INT;
   DECLARE n INT;

   SET a = 'SELECT * FROM PRUEBA A1 ';
   SET b = ' WHERE ';
   SET n = 3;
   SET i = 1;

   WHILE i < n DO
      BEGIN
         CASE i
         WHEN 1 THEN
            SET qry = a;
         WHEN 2 THEN
            SET a = a || 'CROSS JOIN PRUEBA A' || i ; -- Error in this part.
            SET b = b || 'A' || (i-1) || '.CAMPO < A' || i || '.CAMPO';
            SET qry = a || b;
         ELSE
            SET a = a || 'CROSS JOIN PRUEBA A' || i ;
            SET b = b || 'AND A' || (i-1) || '.CAMPO < A' || i || '.CAMPO';
            SET qry = a || b;
         END CASE;
         SET i = i + 1;
      END;
   END WHILE;
   EXECUTE IMMEDIATE qry;
END;

CALL TEST();

I'd join the 'i' variable to create multiple alias for all cross tables.

Answer 1

Your i variable is an INTEGER . Try casting it as a VARCHAR() when you do your concatenations:

SET a = a || 'CROSS JOIN PRUEBA A' || CAST(i AS VARCHAR(2)) ; -- Error in this part.
SET b = b || 'A' || CAST((i-1) AS VARCHAR(2)) || '.CAMPO < A' || 
  CAST(i AS VARCHAR(2)) || '.CAMPO';

You'll have to do this in the subsequent ELSE block as well.

Answer 2

Use explicit CAST or TRIM to avoid the leading blanks generated by implicit cast from INTEGER to VARCHAR. And you need to use a dynamic cursor to return the result of the SELECT to the caller.

REPLACE PROCEDURE TEST()
   DYNAMIC RESULT SETS 1 --Allow returning data to caller
BEGIN
   DECLARE a VARCHAR(255);
   DECLARE b VARCHAR(225);
   DECLARE qry VARCHAR(4096);
   DECLARE i INT;
   DECLARE n INT;
   DECLARE csr1 CURSOR WITH RETURN FOR stmt1; --Declare a dynamic cursor

   SET a = 'SELECT * FROM PRUEBA A1 ';
   SET b = ' WHERE ';
   SET n = 3;
   SET i = 1;

   WHILE i < n DO
      BEGIN
         CASE i
         WHEN 1 THEN
            SET qry = a;
         WHEN 2 THEN
            SET a = a || 'CROSS JOIN PRUEBA A' || TRIM(i) ;
            SET b = b || 'A' || TRIM(i-1) || '.CAMPO < A' || TRIM(i) || '.CAMPO';
            SET qry = a || b;
         ELSE
            SET a = a || 'CROSS JOIN PRUEBA A' || TRIM(i) ;
            SET b = b || 'AND A' || TRIM(i-1) || '.CAMPO < A' || TRIM(i) || '.CAMPO';
            SET qry = a || b;
         END CASE;
         SET i = i + 1;
      END;
   END WHILE;
   PREPARE stmt1 FROM qry; --Prepare a dynamic SQL statement for the cursor
   OPEN csr1; --Execute the SELECT statement
   --Leave a WITH RETURN cursor open to return the result set
END;

Answer 3

if you're using bteq you might have to write the procedure into a file and load it with.compile directive. once you are loggen in and supposing the file is /tmp/stored_procedure.sql compile it like this: .compile file='/tmp/stored_procedure.sql';