DB2开发系列之一——基本语法
最近看了些db2开发方面的资料，现做摘要，以供自己和大家参考：
1、变量声明
DECLARE v_salary DEC(9,2) DEFAULT 0.0;
DECLARE v_status char(3) DEFAULT ‘YES’;
DECLARE v_descrition VARCHAR(80);
DECLARE v1, v2 INT DEFAULT 0;
2、数组数据类型
CREATE TYPE numbers as INTEGER ARRAY[100];
CREATE TYPE names as VARCHAR(30) ARRAY[];
CREATE TYPE MYSCHEMA.totalcomp as DECIMAL(12,2) ARRAY[];
CREATE PROCEDURE PROC_VARRAY_test (out mynames names)
BEGIN
DECLARE v_pnumb numbers;
SET v_pnumb = ARRAY[1,2,3,5,7,11];
SET mynames(1) =’MARINA’;
…
END
3、赋值
1）一般方法
SET var1 = 10;
SET total = (select sum(c1) from T1);
SET var2 = POSSTR(‘MYTEST’,’TEST’);
SET v_numb(10) = 20;
SET v_numb = ARRAY[1,2,3,4];
2）其他方法
VALUES INTO
SELECT (or FETCH) INTO
VALUES 2 INTO v1;
VALUES ‘TEST’ INTO var2;
SELECT SUM(c1) INTO var1 FROM T1;
SELECT POSSTR(‘MYTEST’,’TEST’) INTO v1 FROM SYSIBM.SYSDUMMY1;
4、专用寄存器
1）常用寄存器
CURRENT DATE
CURRENT TIME
CURRENT TIMESTAMP
CURRENT USER
CURRENT PATH
2）示例
CREATE PROCEDURE get_datetime (out cdate date, out ctime time )
P1: BEGIN
VALUES CURRENT DATE INTO cdate;
VALUES CURRENT TIME INTO ctime;
END P1
SET CURRENT_SCHEMA = MYSCHEMA
5、游标
1）声明
DECLARE mycur1 CURSOR
FOR SELECT e.empno, e.lastname, e.job
FROM employee e, department d
WHERE e.workdept = d.deptno
AND deptname =’PLANNING’;
DECLARE v_dept CHAR(3) DEAFULT ‘ ‘;
DECLARE myres_set CURSOR
FOR SELECT empno, lastname, job, salary, comm.
FROM employee
WHERE workdept = v_dept;
2）游标和结果集
CREATE PROCEDURE emp_from_dept()
DYNAMIC RESULT SETS 1
P1: BEGIN
DECLARE c_emp_dept CURSOR WITH RETURN
FOR SELECT empno, lastname, job, salary, comm.
FROM employee
WHERE workdept = ‘E21’;
OPEN c_emp_dept;
END P1
6、条件语句
1）if语句
IF years_of_serv > 30 THEN
SET gl_sal_increase = 15000;
ELSEIF years_of_serv > 20 THEN
SET gl_sal_increase = 12000;
ELSE
SET gl_sal_increase = 10000;
END IF;
2）CASE语句
CREATE PROCEDURE sal_increase_lim1 (empid CHAR(6))
BEGIN
DECLARE years_of_serv INT DEFAULT 0;
DECLARE v_incr_rate DEC(9,2) DEFAULT 0.0;
SELECT YEAR(CURRENT DATE) – YEAR(hiredate)
INTO years_of_serv
FROM empl1
WHERE empno = empid;
CASE
WHEN years_of_serv > 30 THEN
SET v_incr_rate = 0.08;
WHEN years_of_serv > 20 THEN
SET v_incr_rate = 0.07;
WHEN years_of_serv > 10 THEN
SET v_incr_rate = 0.05;
ELSE
SET v_incr_rate = 0.04;
END CASE;
UPDATE empl1
SET salary = salary+salary*v_incr_rate
WHERE empno = empid;
END
3）迭代语句
LOOP 循环 — 简单的循环
L1: LOOP
SQL statements;
LEAVE L1;
END LOOP L1;
WHILE 循环 — 进入前检查条件
WHILE condition
DO
SQL statements
END WHILE;
REPEAT 循环 — 退出前检查条件
REPEAT
SQL statements;
UNTIL condition
END REPEAT;
FOR 循环 — 结果集上的隐式循环
FOR loop_name AS
SELECT … FROM
DO
SQL statements;
END FOR;
CREATE PROCEDURE LEAVE_LOOP (DEPTIN char(3), OUT p_counter INTEGER)
Ll: BEGIN
DECLARE v_at_end , v_counter INTEGER DEFAULT 0;
DECLARE v_lastname VARCHAR(15);
DECLARE v_birthd, v_hired DATE;
DECLARE c1 CURSOR
FOR SELECT lastname, hiredate, birthdate FROM employee
WHERE WORKDEPT = deptin;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_at_end = 1;
OPEN c1;
FETCH_LOOP: LOOP
FETCH c1 INTO v_lastname, v_hired, v_birthd;
IF v_at_end <> 0 THEN — loop until last row of the cursor
LEAVE FETCH_LOOP;
END IF;
SET v_counter = v_counter + 1;
INSERT INTO REPORT_INFO_DEPT
values(v_lastname, v_hired, v_birthd);
END LOOP FETCH_LOOP;
SET p_counter = v_counter;
END Ll
CREATE PROCEDURE DEPT_REPT (DEPTIN char(3), OUT p_counter INTEGER)
Pl: BEGIN
DECLARE v_at_end , v_counter INTEGER DEFAULT 0;
DECLARE v_lastname VARCHAR(15);
DECLARE v_birthd, v_hired DATE;
DECLARE c1 CURSOR
FOR SELECT lastname, hiredate, birthdate FROM employee
WHERE WORKDEPT = deptin;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET v_at_end = 1;
OPEN c1;
FETCH c1 INTO v_lastname, v_hired, v_birthd;
WHILE (v_at_end = 0)
DO
INSERT INTO REPORT_INFO_DEPT
values(v_lastname, v_hired, v_birthd);
SET v_counter = v_counter + 1;
FETCH c1 INTO v_lastname, v_hired, v_birthd;
END WHILE;
SET p_counter = v_counter;
END P1
CREATE PROCEDURE DEPT_REPT1 (DEPTIN char(3), OUT p_counter INT)
P1:BEGIN
DECLARE v_counter INT DEFAULT 0;
FOR dept_loop AS
SELECT lastname, hiredate, birthdate FROM employee
WHERE WORKDEPT = deptin
DO
INSERT INTO REPORT_INFO_DEPT values
(dept_loop.lastname,dept_loop.hiredate,dept_loop.birthdate);
SET v_counter = v_counter + 1;
END FOR;
SET p_counter = v_counter;
END P1
7、异常处理机制
1）DECLARE 有名称的条件
DECLARE FOREIGN_KEY_VIOLATION CONDITION FOR SQLSTATE ‘23503’;
DECLARE overflow CONDITION FOR SQLSTATE ‘22003’;
2）DECLARE 条件处理程序
CREATE PROCEDURE simple_error
(IN new_job CHAR(8), IN p_empno CHAR(6),
OUT p_state_out CHAR(5),OUT p_code_out INT)
SPECIFIC simple_error1
BEGIN
DECLARE SQLCODE INT DEFAULT 0;
DECLARE SQLSTATE CHAR(5) DEFAULT ‘00000’;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
SELECT SQLSTATE, SQLCODE
INTO p_sqlstate_out, p_sqlcode_out
FROM SYSIBM.SYSDUMMY1;
UPDATE EMPLOYEE
SET job = new_job
WHERE empno = p_empno;
END
CREATE PROCEDURE proc1 (IN num int, IN new_status varchar(10))
P1: BEGIN
DECLARE SQLCODE INTEGER default 0;
DECLARE SQLSTATE CHAR(5) default ‘ ‘;
DECLARE v_trunc INTEGER default 0;
DECLARE overflow CONDITION FOR SQLSTATE ‘22001’;
DECLARE CONTINUE HANDLER FOR overflow
BEGIN
INSERT INTO tab1 VALUES (num, substr (new_sataus,1,5));
SET v_trunc = 2;
END;
INSERT INTO tab1 VALUES(num, new_status);
RETURN v_trunc;
END P1
3）强制发出异常 — SIGNAL SQLSTATE
DECLARE condition overflow for SQLSTATE ‘22001’;
…
SIGNAL overflow SET MESSAGE_TEXT = ‘Too many characters, truncated’;
CREATE PROCEDURE sign_test (IN num int, IN new_status varchar(10))
P1: BEGIN
DECLARE SQLCODE INTEGER default 0;
DECLARE SQLSTATE CHAR(5) default ”;
IF length (new_status) > 5 THEN
SIGNAL SQLSTATE ‘72001’ SET MESSAGE_TEXT = ‘INPUT VALUE TOO LONG’;
END IF;
INSERT INTO TAB1 VALUES (num, new_status);
END P1