《oracle pl/sql programming》 第一章 介绍 第二章 sql*plus
第一章 介绍
1. what's pl/sql
It is a highly structured, readable, and accessible language
高度結構化
，
易讀的
，
易理解的
It is a standard and portable language for Oracle development
標準的
，
輕便的
It is an embedded language
嵌入式的
，
運行是需要宿主環境
It is a high-performance, highly integrated database language
高性能
，
與數據庫高度集成
2.
歷史
，
與版本
（
略
）
3.
代碼樣例
3.1
基本結構
1 DECLARE
2 l_book_count INTEGER;
3
4 BEGIN
5 SELECT COUNT(*)
6 INTO l_book_count
7 FROM books
8 WHERE author LIKE '%FEUERSTEIN, STEVEN%';
9
10 DBMS_OUTPUT.PUT_LINE (
11 'Steven has written (or co-written) ' ||
12 l
_book_count ||
13 ' books.');
14
15 -- Oh, and I changed my name, so...
16 UPDATE books
17 SET author = REPLACE (author, 'STEVEN', 'STEPHEN')
18 WHERE author LIKE '%FEUERSTEIN, STEVEN%';
19 END;
3.2 procedure
樣例
1 CREATE OR REPLACE PROCEDURE pay_out_balance (
2 account_id_in IN accounts.id%TYPE)
3 IS
4 l_balance_remaining NUMBER;
5 BEGIN
6 LOOP
7 l_balance_remaining := account_balance (account_id_in);
8
9 IF l_balance_remaining < 1000
10 THEN
11 EXIT;
12 ELSE
13 apply_balance (account_id_in, l_balance_remaining);
14 END IF;
15 END LOOP;
16 END pay_out_balance;
3.3
帶異常處理的
procedure
結構
1 CREATE OR REPLACE PROCEDURE check_account (
2 account_id_in IN accounts.id%TYPE)
3 IS
4 l_balance_remaining NUMBER;
5 l_balance_below_minimum EXCEPTION;
6 l_account_name accounts.name%TYPE;
7 BEGIN
8 SELECT name
9 INTO l_account_name
10 FROM accounts
11 WHERE id = account_id_in;
12
13 l
_balance_remaining := account_balance (account_id_in);
14
15 DBMS_OUTPUT.put_line (
16 'Balance for ' || l_account_name ||
17 ' = ' || l_balance_remaining);
18
19 IF l_balance_remaining < 1000
20 THEN
21 RAISE l_balance_below_minimum;
22 END IF;
23
24 EXCEPTION
25 WHEN NO_DATA_FOUND
26 THEN
27 -- No account found for this ID
28 log_error (...);
29
30 WHEN l_balance_below_minimum
31 THEN
32 log_error (...);
33 RAISE;
34 END;
4.
學習資源
（
略
）
5.
一些建議
5.1
欲速則不達
在撰寫代碼之前構建測試用例與編寫測試腳本
建立清晰的應用程序編碼規則及需要程序員共同遵守的約定
使用
“
逐步求精
”
的步驟和方法來簡化復雜性
5.2
不恥下問
承認自己的無知
需求幫助
將問題和答案整理歸類
5.3
發揮你的激情和創造力
，
不要輕易退縮
第二章 pl*sql
1.
啟動
sql*plus
并連接數據庫
os> sqlplus username/password
os> sqlplus /nolog
sql> connect username/password@databaseinfo
2
運行代碼
sql> BEGIN
2 DBMS_OUTPUT.PUT_LINE('Hey look, ma!');
3 END;
4 / --
斜杠
/
表示運行
此時無顯示。
sql>set serveroutput on
sql> BEGIN
2 DBMS_OUTPUT.PUT_LINE('Hey look, ma!');
3 END;
4 / --
斜杠
/
表示運行
顯示結果
：Hey look, ma!
以上
begin ...end
與
EXECUTE
是等價的
，
如
：
sql>EXECUTE DBMS_OUTPUT.PUT_LINE('Hey look,ma!');
sql>@scriptfilename;
or
sql>start scriptfilename;
3
什么是當前路徑
當前路徑指的是進入
sql*plus
前所在的操作系統路徑
，
如
：
c:/> sqlplus username/password
sql>_
此時的當前路徑為
c:/
4. define
與
variable
相當于
c
語言里的宏與變量
SQL> DEFINE x = "the answer is 42"
SQL> VARIABLE x VARCHAR2(10)
SQL> BEGIN
2 :x := 'hullo';
3 END;
4 /
SQL> SELECT :x, '&x' FROM DUAL;
返回結果如下
：
:X 'THEANSWERIS42'
-------------------------------- ----------------
hullo the answer is 42
5.
將輸出結果保存到文件
SQL> SPOOL report
SQL> @run_report
......
SQL> SPOOL OFF
SQL> SPOOL report.txt
6.
退出
sql*plus
sql>disconnect;
sql>exit;
7.
編輯腳本
sql> edit mySQLScript.pkg --
調用默認的編輯器進行編輯
sql> DEFINE _EDITOR = c:/windows/notepad.exe --
設置默認的編輯器
8.
在啟動時加載自定義環境
sql*plus
在啟動時
，
若發現存在
$ORACLE_HOME/qlplus/admin/glogin.sql
，
就會自動運行它。
然后如果在當前目錄下發現
login.sql,
則自動運行它。
因此
，
可以在這兩個文件中加入自定義
sql*plus
環境的代碼
，
如
：
REM Number of lines of SELECT statement output before reprinting headers
SET PAGESIZE 999
REM Width of displayed page, expressed in characters
SET LINESIZE 132
REM Enable display of DBMS_OUTPUT messages. Use 1000000 rather than
REM "UNLIMITED" for databases earlier than Oracle Database 10g Release 2
SET SERVEROUTPUT ON SIZE UNLIMITED FORMAT WRAPPED
REM Change default to "vi improved" editor
DEFINE _EDITOR = /usr/local/bin/vim
REM Format misc columns commonly retrieved from data dictionary
COLUMN segment_name FORMAT A30 WORD_WRAP
COLUMN object_name FORMAT A30 WORD_WRAP
REM set the prompt (works in SQL*Plus from Oracle9i Database or later)
SET SQLPROMPT "_USER'@'_CONNECT_IDENTIFIER > "
注
：REM
表示注釋。
9. sql*plus
的錯誤處理
sql*plus
執行代碼時時遇到錯誤時的默認處理方式是返回錯誤消息并繼續處理后續代碼。
如果希望
sql*plus
遇到錯誤是終止執行
，
則執行如下代碼
：
SQL> WHENEVER SQLERROR EXIT SQL.SQLCODE
如果還希望回滾事務
，
則執行如下代碼
：
SQL> WHENEVER SQLERROR SQL.SQLCODE EXIT ROLLBACK
10. sql*plus
的愛與恨
love:
With SQL*Plus , you can run "batch" programs, supplying application-specific arguments on the sqlplus command line, and referring to them in the script using &1 (first argument), &2 (second argument), etc.
SQL*Plus provides complete and up-to-date support for all SQL and PL/SQL statements. This can be important when you're using features unique to Oracle. Third-party environments may not provide 100% coverage; for example, some have been slow to add support for Oracle's object types, which were introduced a number of years ago.
SQL*Plus runs on all of the same hardware and operating system platforms on which the Oracle server runs.
hate:
In console versions of SQL*Plus, the statement buffer is limited to the most recently used statement; SQL*Plus offers no further command history.
With SQL*Plus, there are no modern command-interpreter features such as automatic completion of keywords or hints about which database objects are available while typing in a statement.
Online help consists of minimal documentation of the SQL*Plus command set. (Use HELP command to get help on a specific command.)
There is no ability to change the current directory once you've started SQL*Plus. This can be annoying when opening or saving scripts if you don't like typing full pathnames. If you discover that you're in an inconvenient directory, you have to quit SQL*Plus, change directories, and restart SQL*Plus.
Unless I break down and use what I consider the dangerous SQLPATH feature, SQL*Plus looks only in the startup directory for login.sql; it would be better if it would fall back to look in my home directory for the startup script.