SYBASE 数据库迁移到AS 400 db2的FAQ（三）

SYBASE 数据库迁移到AS 400 db2的FAQ（三） 21．Db2中SQLSTATE的代号如何定义？

答：如下

Class Code 00: Unqualified Successful Completion

Class Code 01: Warning

Class Code 02: No Data

Class Code 07: Dynamic SQL Error

Class Code 08: Connection Exception

Class Code 09: Triggered Action Exception

Class Code 0A: Feature Not Supported

Class Code 0E: Invalid Schema Name List Specification

Class Code 0F: Invalid Token

Class Code 0K: Resignal When Handler Not Active

Class Code 20: Case Not Found for Case Statement

Class Code 21: Cardinality Violation

Class Code 22: Data Exception

Class Code 23: Constraint Violation

Class Code 24: Invalid Cursor State

Class Code 25: Invalid Transaction State

Class Code 26: Invalid SQL Statement Identifier

Class Code 27: Triggered Data Change Violation

Class Code 28: Invalid Authorization Specification

Class Code 2D: Invalid Transaction Termination

Class Code 2E: Invalid Connection Name

Class Code 2F: SQL Function Exception

Class Code 34: Invalid Cursor Name

Class Code 38: External Function Exception

Class Code 39: External Function Call Exception

Class Code 3B: Savepoint Exception

Class Code 3C: Ambiguous Cursor Name

Class Code 42: Syntax Error or Access Rule Violation

Class Code 44: WITH CHECK OPTION Violation

Class Code 46: Java Errors

Class Code 51: Invalid Application State

Class Code 54: SQL or Product Limit Exceeded

Class Code 55: Object Not in Prerequisite State

Class Code 56: Miscellaneous SQL or Product Error

Class Code 57: Resource Not Available or Operator Intervention

Class Code 58: System Error

22．如何对当前游标的行数据进行删除，更新操作？

答：例如 DECLARE THISEMP CURSOR FOR SELECT EMPNO, LASTNAME,

WORKDEPT, JOB

FROM CORPDATA.EMPLOYEE

FOR UPDATE OF JOB ;

open THISEMP ;

…

UPDATE CORPDATA.EMPLOYEE

SET JOB = :NEW-CODE

WHERE CURRENT OF THISEMP

…

23．Db2中使用 NOT FOUND 控制游标？

答：NOT FOUND是DB2中的全局变量，可以等同于如下

IF SQLCODE =100 GO TO DATA-NOT-FOUND.

EXEC SQL

WHENEVER NOT FOUND GO TO symbolic-address

END-EXEC.

IF SQLSTATE ='02000' GO TO DATA-NOT-FOUND.

24．DB2下动态游标如何定义和使用？

答：给出一个例子

CREATE PROCEDURE CREATE_DEPT_TABLE (IN P_DEPT CHAR(3))

LANGUAGE SQL

BEGIN

DECLARE STMT CHAR(1000);

DECLARE MESSAGE CHAR(20);

DECLARE TABLE_NAME CHAR(30);

DECLARE CONTINUE HANDLER FOR SQLEXCEPTION

SET MESSAGE = 'ok';

SET TABLE_NAME = 'CORPDATA.DEPT_' CONCAT P_DEPT CONCAT '_T';

SET STMT = 'DROP TABLE ' CONCAT TABLE_NAME;

PREPARE S1 FROM STMT;

EXECUTE S1;

SET STMT = 'CREATE TABLE ' CONCAT TABLE_NAME CONCAT

'( EMPNO CHAR(6) NOT NULL,

FIRSTNME VARCHAR(12) NOT NULL,

MIDINIT CHAR(1) NOT NULL,

LASTNAME CHAR(15) NOT NULL,

SALARY DECIMAL(9,2))';

PREPARE S2 FROM STMT;

EXECUTE S2;

SET STMT = 'INSERT INTO ' CONCAT TABLE_NAME CONCAT

'SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY

FROM CORPDATA.EMPLOYEE

WHERE WORKDEPT = ?';

PREPARE S3 FROM STMT;

EXECUTE S3 USING P_DEPT;

END;

25．DB2下在存储过程中，直接执行sql语句，如何定义和使用？

答：举例如下

CREATE PROCEDURE CREATE_DEPT_TABLE (IN P_DEPT CHAR(3))

LANGUAGE SQL

BEGIN

DECLARE STMT CHAR(1000);

DECLARE MESSAGE CHAR(20);

DECLARE TABLE_NAME CHAR(30);

DECLARE CONTINUE HANDLER FOR SQLEXCEPTION

SET MESSAGE = 'ok';

SET TABLE_NAME = 'CORPDATA.DEPT_' CONCAT P_DEPT CONCAT '_T';

SET STMT = 'DROP TABLE ' CONCAT TABLE_NAME;

PREPARE S1 FROM STMT;

EXECUTE S1;

SET STMT = 'CREATE TABLE ' CONCAT TABLE_NAME CONCAT

'( EMPNO CHAR(6) NOT NULL,

FIRSTNME VARCHAR(12) NOT NULL,

MIDINIT CHAR(1) NOT NULL,

LASTNAME CHAR(15) NOT NULL,

SALARY DECIMAL(9,2))';

PREPARE S2 FROM STMT;

EXECUTE S2;

SET STMT = 'INSERT INTO ' CONCAT TABLE_NAME CONCAT

'SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY

FROM CORPDATA.EMPLOYEE

WHERE WORKDEPT = ?';

PREPARE S3 FROM STMT;

EXECUTE S3 USING P_DEPT;

END;

26．DB2是否支持多重事务？是如何实现的？

答: DB2支持多重事务，使用SAVEPOINT的机制管理多重事务处理。允许在一个事务中设置多个保存点，而出错是回滚到指定保存点。

COMMIT

ROLLBACK

SET TRANSACTION

SAVEPOINT STOP_HERE ON ROLLBACK RETAIN CURSORS;

SAVEPOINT START_OVER UNIQUE ON ROLLBACK RETAIN CURSORS；

RELEASE SAVEPOINT START_OVER

27．Sybase 使用raiserror 99999 ‘xxxx’自定义错误信息，db2如何实现自定义错误？

答：使用signal SQLSTATE＇ii0002＇ set message_text = ‘dddd’; 指定SQLSTATE信息返回自定义的错误信息。注意sqlstate 必须是 5 位字符，可以是 0 – 9 ，不允许大写字符A-Z和其他特殊字符。不允许前两个字符是‘00’。Message_text 信息限制在70字节长度。

举例如下

CREATE PROCEDURE raise ( IN rating INTEGER )

LANGUAGE SQL

BEGIN

DECLARE new_salary DECIMAL(9,2);

DECLARE service DECIMAL(8,0);

DECLARE v_empno CHAR(6) DEFAULT '123456';

SELECT salary, current_date - hiredate

INTO new_salary, service

FROM employee

WHERE empno = v_empno;

IF service < 600

THEN SIGNAL SQLSTATE 'II001'

SET MESSAGE_TEXT = 'Insufficient time in service.';

END IF;

IF rating = 1

THEN SET new_salary =

new_salary + (new_salary * .10);

ELSEIF rating = 2

THEN SET new_salary =

new_salary + (new_salary * .05);

END IF;

UPDATE employee

SET salary = new_salary

WHERE empno = v_empno;

END;

28．Db2中return的限制和使用？

答： return 不允许在触发器中使用。

29．Db2中如何创建trigger？

答：Db2的trigger 和Sybase 的触发器有些区别，Sybase中触发器全部市after方式。

Db2可以定义触发器的触发时机(after,before)

具体格式：

create Trigger info_plu_ti after insert on info_plu_tab Referencing New as new for each row

30．Db2的CASE 控制语句用法和例子？

答：用法举例如下：

CASE evaluation

WHEN 100 THEN UPDATE employee SET salary = salary * 1.3;

WHEN 90 THEN UPDATE employee SET salary = salary * 1.2;

WHEN 80 THEN UPDATE employee SET salary = salary * 1.1;

ELSE UPDATE employee SET salary = salary * 1.05;

END CASE;

或者：

CASE

WHEN evaluation = 100 THEN UPDATE employee SET salary = salary * 1.3;

WHEN evaluation = 90 THEN UPDATE employee SET salary = salary * 1.2;

WHEN evaluation = 80 THEN UPDATE employee SET salary = salary * 1.1;

ELSE UPDATE employee SET salary = salary * 1.05;

END CASE;

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