Prayer

33．Db2的循環控制語句repeat用法？
答：repeat例子
SET numrec = 0;
fetch_loop:
REPEAT
FETCH c1 INTO proc_cusnbr, proc_cuscrd;
IF SQLCODE = 0 THEN
SET proc_cuscrd = proc_cuscrd * 1.2;
UPDATE ordapplib.customer
SET cuscrd = proc_cuscrd
WHERE CURRENT OF c1;
SET numrec = numrec + 1;
END IF;
UNTIL SQLCODE <> 0
END REPEAT fetch_loop;


34．Db2的循環控制語句for用法？
答：for 例子
FOR each_record AS
cursor1 CURSOR FOR
SELECT cusnbr, cuscrd FROM ordapplib.customer
DO
UPDATE ordapplib.customer
SET cuscrd = cuscrd * 1.1
WHERE CURRENT OF cursor1;
END FOR;

34．循環控制Break,Continue在Db2用法？
答：在db2中 Break 轉換為leave lab, Continue 轉換為ITERATE lab
等同于GOTO語句
舉例如下：
============== leave 例子
OPEN c1;
SET at_end = 0;
SET numrec = 0;
fetch_loop: 1
LOOP
FETCH c1 INTO proc_cusnbr, proc_cuscrd;
IF SQLCODE = 0 THEN
SET proc_cuscrd = proc_cuscrd * 1.2;
UPDATE ordapplib.customer
SET cuscrd = proc_cuscrd
WHERE CURRENT OF c1;
SET numrec = numrec + 1;
ELSE
LEAVE fetch_loop; 2
END IF;
END LOOP fetch_loop;
CLOSE c1;
============ iterate 例子
BEGIN
OPEN c1;
ins_loop: 1
LOOP
FETCH c1 INTO v_dept, v_deptname, v_admdept;
IF at_end = 1 THEN
LEAVE ins_loop;
ELSEIF v_dept = 'D11' THEN
ITERATE ins_loop; 2
END IF;
INSERT INTO sampledb02.deptnew (deptno, deptname, admrdept)
VALUES (v_dept, v_deptname, v_admdept);
END LOOP;
CLOSE c1;
END;
35．在Db2存儲過程中使用滾動游標（scrollable cursor）？
答：例子
CREATE PROCEDURE MYMAX
( IN fld_name CHAR(30),
IN file_name CHAR(128),
INOUT max_value INTEGER)
LANGUAGE SQL
BEGIN atomic
DECLARE sql_stmt CHAR(256);
DECLARE not_found
CONDITION FOR '02000';
DECLARE c1 DYNAMIC SCROLL CURSOR FOR s1; -- 聲明動態滾動游標
DECLARE CONTINUE HANDLER FOR not_found
SET max_value = NULL;
SET sql_stmt = 'SELECT ' || fld_name || ' FROM ' || file_name ||
' ORDER BY 1'; --組合sql語句
PREPARE s1 FROM sql_stmt;
OPEN c1;
FETCH LAST FROM c1 INTO max_value; --轉到最后行
CLOSE c1;
END
滾動游標的使用例子：（rpg）
EXEC SQL BEGIN DECLARE SECTION;
char fld_name[ 30 ];
char file_name[ 128 ];
integer max_value;
short ind3;
EXEC SQL END DECLARE SECTION;
Then the indicator variable is used in the call statement:
EXEC SQL
CALL MYMAX( :fld_name, :file_name, :max_value :ind3);

36．db2中存儲過程中使用動態游標（dynamic cursor）？
答：使用PREPARE ， EXECUTE ，EXECUTE IMMEDIATE語句
例子：
CREATE PROCEDURE DYNSQLSAMPLE()
LANGUAGE SQL
BEGIN
DECLARE stmt VARCHAR(256);
SET stmt = 'UPDATE employee SET salary = salary * 1.1 WHERE empno = ?'; 1
PREPARE s1 FROM stmt;
ins_loop:
FOR each_department AS
c1 CURSOR FOR
SELECT mgrno FROM department WHERE mgrno IS NOT NULL
DO
EXECUTE s1 USING mgrno;
END FOR;
END;
EXECUTE IMMEDIATE statement 例子：
PREPARE s1 FROM ‘UPDATE employee SET salary = salary * 1.1 WHERE
empno IN (SELECT DISTINCT mgrno FROM department WHERE mgrno IS NOT NULL);
EXECUTE s1;
等同于
EXECUTE IMMEDIATE ‘UPDATE employee SET salary = salary * 1.1 WHERE
empno IN (SELECT DISTINCT mgrno FROM department WHERE mgrno IS NOT NULL);

最基本動態游標語句
...
DECLARE stmt VARCHAR[256];
...
SET stmt = ‘SELECT COLUMN1, COLUMN2, COLUMN3 FROM TBL1’;
PREPARE PreparedStatement FROM s1;
DECLARE Cursor1 CURSOR FOR PreparedStatement;