Sometimes some complex business logic will be processed through the loop statement of the stored procedure; the following lists the loop statements of the two DB2 stored procedures, which is convenient for future viewing and use!
The use of the first method is recommended. The biggest advantage is that it is more intuitive; in the case of many fields to be manipulated, there is no need to define too many field variables as an intermediate storage medium.
1. FOR method (FOR .. AS [cursor name] CURSOR FOR [SELECT...])
BEGIN -- statement block, must be added, otherwise an error will occur.
FOR V AS MYCURSOR CURSOR FOR SELECT ID,NAME,AGE FROM PEOPLE
DO
BEGIN
--Business logic processing is performed here. When each row is looped, the value of each column will be stored in the V variable
--Example: insert data into another table
INSERT INTO PERSON(NAME,AGE) VALUES(V.NAME,V.AGE);
END;
END FOR;
END;
2. WHILE method (DECLARE [cursor name] CURSOR FOR [SELECT.....])
BEGIN -- statement block, must be added, otherwise an error will occur.
DECLARE NOTFOUND INT DEFAULT 0;
DECLARE V_NAME VARCHAR(20);
DECLARE V_AGE VARCHAR(20);
DECLARE MYCURSOR CURSOR FOR SELECT NAME,AGE FROM PEOPLE;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET NOTFOUND = 1;
WHILE NOTFOUND = 0 DO FETCH MYCURSOR INTO V_NAME,V_AGE -- the order here should be consistent with the query result field order
--There will be one more loop here, so you need to add a judgment
IF(NOTFOUND = 0)
THEN
INSERT INTO PERSON(NAME,AGE) VALUES(V_NAME,V_AGE);
END IF;
END WHILE;
END;
Copied from netizens, original address: https://www.cnblogs.com/javalism/p/3511742.html
The use of the first method is recommended. The biggest advantage is that it is more intuitive; in the case of many fields to be manipulated, there is no need to define too many field variables as an intermediate storage medium.
1. FOR method (FOR .. AS [cursor name] CURSOR FOR [SELECT...])
BEGIN -- statement block, must be added, otherwise an error will occur.
FOR V AS MYCURSOR CURSOR FOR SELECT ID,NAME,AGE FROM PEOPLE
DO
BEGIN
--Business logic processing is performed here. When each row is looped, the value of each column will be stored in the V variable
--Example: insert data into another table
INSERT INTO PERSON(NAME,AGE) VALUES(V.NAME,V.AGE);
END;
END FOR;
END;
2. WHILE method (DECLARE [cursor name] CURSOR FOR [SELECT.....])
BEGIN -- statement block, must be added, otherwise an error will occur.
DECLARE NOTFOUND INT DEFAULT 0;
DECLARE V_NAME VARCHAR(20);
DECLARE V_AGE VARCHAR(20);
DECLARE MYCURSOR CURSOR FOR SELECT NAME,AGE FROM PEOPLE;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET NOTFOUND = 1;
WHILE NOTFOUND = 0 DO FETCH MYCURSOR INTO V_NAME,V_AGE -- the order here should be consistent with the query result field order
--There will be one more loop here, so you need to add a judgment
IF(NOTFOUND = 0)
THEN
INSERT INTO PERSON(NAME,AGE) VALUES(V_NAME,V_AGE);
END IF;
END WHILE;
END;
Copied from netizens, original address: https://www.cnblogs.com/javalism/p/3511742.html