在NDS中使用PL/SQL块来完成更新CLOB字段,注意USING子句中的参数传递模式应与存储过程传递参数的模式一致.
00:22:39 SCOTT@orcl> --建立PL/SQL存储过程,更新CLOB字段为空
00:41:02 SCOTT@orcl> CREATE OR REPLACE PROCEDURE get_clob(item_title_in VARCHAR2,
00:41:02 2 item_desc_out IN OUT CLOB) IS
00:41:02 3 BEGIN
00:41:02 4 UPDATE item
00:41:02 5 SET item_desc = empty_clob()
00:41:02 6 WHERE item_title = item_title_in
00:41:02 7 RETURNING item_desc INTO item_desc_out;
00:41:02 8 END get_clob;
00:41:03 9 /
Procedure created.
Elapsed: 00:00:00.27
00:41:05 SCOTT@orcl> DECLARE
00:42:50 2 -- Define explicit record structure.
00:42:50 3 target CLOB;
00:42:50 4 source VARCHAR2(2000) := 'CryKing!';
00:42:50 5 movie VARCHAR2(60) := 'TEST_TITLE';
00:42:50 6 stmt VARCHAR2(2000);
00:42:50 7 BEGIN
00:42:50 8 -- Set statement
00:42:50 9 stmt := 'BEGIN ' || ' get_clob(:input,:output); ' || 'END;';
00:42:50 10 EXECUTE IMMEDIATE stmt
00:42:50 11 USING movie, IN OUT target;
00:42:50 12 dbms_lob.writeappend(target, LENGTH(source), source);
00:42:50 13 END;
00:42:51 14 /
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.02
00:42:53 SCOTT@orcl> select * from item;
ITEM_ID ITEM_TITLE ITEM_DESC
---------- ---------- ------------------
1 TEST_TITLE CryKing!
1 row selected.
Elapsed: 00:00:00.01你不能在执行动态PL/SQL块时使用RETURING INTO子句,因为RETURING INTO子句只能在有INSERT,UPDATE,DELETE语句时使用.
不定个数的输入参数的动态语句
此时需要使用DBMS_SQL包
示例:
11:29:29 SCOTT@orcl> create table emp_bak as select * from emp;
表已创建。
已用时间: 00: 00: 02.39
11:38:39 SCOTT@orcl> DECLARE
11:38:40 2 -- Declare explicit record structure and table of structure.
11:38:40 3 TYPE emp_record IS RECORD(
11:38:40 4 empno VARCHAR2(60)
11:38:40 5 ,ename VARCHAR2(60));
11:38:40 6 TYPE emp_table IS TABLE OF emp_record;
11:38:40 7 -- Declare dynamic variables.
11:38:40 8 emp_cursor SYS_REFCURSOR;
11:38:40 9 emp_rows emp_table;
11:38:40 10 -- Declare DBMS_SQL variables.
11:38:40 11 c INTEGER := dbms_sql.open_cursor;
11:38:40 12 fdbk INTEGER;
11:38:40 13 -- Declare local variables.
11:38:40 14 counter NUMBER := 1;
11:38:40 15 column_names DBMS_SQL.VARCHAR2_TABLE;
11:38:40 16 emp_nos DBMS_SQL.NUMBER_TABLE;
11:38:40 17 stmt VARCHAR2(2000);
11:38:40 18 substmt VARCHAR2(2000) := '';
11:38:40 19 BEGIN
11:38:40 20 -- Find the rows that meet the criteria.
11:38:40 21 FOR i IN (SELECT 'emp_nos' AS column_names
11:38:40 22 ,empno
11:38:40 23 FROM emp_bak
11:38:40 24 WHERE REGEXP_LIKE(ename, '^S'))
11:38:40 25 LOOP
11:38:40 26 column_names(counter) := counter;
11:38:40 27 emp_nos(counter) := i.empno;
11:38:40 28 counter := counter + 1;
11:38:40 29 END LOOP;
11:38:40 30 -- Dynamically create substatement.
11:38:40 31 IF emp_nos.COUNT = 1 THEN
11:38:40 32 substmt := 'WHERE empno IN (:emp_nos)';
11:38:40 33 ELSE
11:38:40 34 substmt := 'WHERE empno IN (';
11:38:40 35 FOR i IN 1 .. emp_nos.COUNT
11:38:40 36 LOOP
11:38:40 37 IF i = 1 THEN
11:38:40 38 substmt := substmt || ':' || i;
11:38:40 39 ELSE
11:38:40 40 substmt := substmt || ',:' || i;
11:38:40 41 END IF;
11:38:40 42 END LOOP;
11:38:40 43 substmt := substmt || ')';
11:38:40 44 END IF;
11:38:40 45 -- Set statement.
11:38:40 46 stmt := 'SELECT empno, ename ' || 'FROM emp_bak ' || substmt;
11:38:40 47 --输出查看
11:38:40 48 dbms_output.put_line('stmt:' || stmt);
11:38:40 49 -- Parse the statement with DBMS_SQL.
11:38:40 50 dbms_sql.parse(c, stmt, dbms_sql.native);
11:38:40 51 -- Bind the bind variable name and value.
11:38:40 52 FOR i IN 1 .. emp_nos.COUNT
11:38:40 53 LOOP
11:38:40 54 dbms_sql.bind_variable(c, column_names(i), emp_nos(i));
11:38:40 55 END LOOP;
11:38:40 56 -- Execute using DBMS_SQL.
11:38:40 57 fdbk := dbms_sql.execute(c);
11:38:40 58 -- Convert the cursor to NDS.
11:38:40 59 emp_cursor := dbms_sql.to_refcursor(c);
11:38:40 60 -- Open and read dynamic cursor, then close it.
11:38:40 61 FETCH emp_cursor BULK COLLECT
11:38:40 62 INTO emp_rows;
11:38:40 63 FOR i IN 1 .. emp_rows.COUNT
11:38:40 64 LOOP
11:38:40 65 dbms_output.put_line('[' || emp_rows(i).empno || '][' || emp_rows(i)
11:38:40 66 .ename || ']');
11:38:40 67 END LOOP;
11:38:40 68 -- Close the System Reference Cursor.
11:38:40 69 CLOSE emp_cursor;
11:38:40 70 END;
11:38:40 71 /
stmt:SELECT empno, ename FROM emp_bak WHERE empno IN (:1,:2)
[7369][SMITH]
[7788][SCOTT]
PL/SQL 过程已成功完成。
已用时间: 00: 00: 00.01上面的示例动态的构建了一个sql语句(SELECT empno, ename FROM emp_bak WHERE empno IN (:1,:2)).
使用循环来绑定所有的绑定变量(:1,:2,:3...)到emp_nos关联数组(emp_nos存放的是满足查询条件的主键empno).
还使用了DBMS_SQL.TO_REFCURSOR函数将标准的DBMS_SQL游标转换为弱类型的系统游标.这里会自动关闭DBMS_SQL游标.如果
你在DBMS_SQL.TO_REFCURSOR之后再执行DBMS_SQL.close_cursor你将会获得错误ORA-29471.
DBMS_SQL包
oracle公司从oracle 7开始引进DBMS_SQL包.它提供了一种方法来存储用来动态构建SQL语句的对象代码.
在DBMS_SQL之前,你不能存储SQL语句,除非存在相同定义的表.
在8i的时候,DBMS_SQL开始支持集合类型.
DBMS_SQL仍有一个主要的特性是NDS没有的.那就是当返回字段的数据类型及数量未知时它能动态管理语句.
它由两个存储来完成:DESCRIBE_COLUMNS和DESCRIBE_COLUMNS2.
像NDS一样,DBMS_SQL也支持字符串的拼接和绑定变量.
DBMS_SQL包是SYS模式拥有的.有时有必要先给SYSTEM用户赋予权限.然后你可以给单独的用户再赋予使用权限.
如:
00:31:33 SYS@ORCL> GRANT EXECUTE ON dbms_sql TO system WITH GRANT OPTION; Grant succeeded. Elapsed: 00:00:00.08
使用DBMS_SQL包来执行动态的DDL语句
--注意本例运行在SQL*PLUS下,并使用了替换变量
00:41:21 SCOTT@orcl> DECLARE
00:41:48 2 -- Define local DBMS_SQL variables, and open cursor.
00:41:48 3 c INTEGER := dbms_sql.open_cursor;
00:41:48 4 fdbk INTEGER;
00:41:48 5 stmt VARCHAR2(2000);
00:41:48 6 BEGIN
00:41:48 7 -- Use a loop to check whether to drop a sequence.
00:41:48 8 FOR i IN (SELECT null
00:41:48 9 FROM user_objects
00:41:48 10 WHERE object_name = '&&1') LOOP
00:41:48 11 -- Build, parse, and execute SQL statement, then close cursor.
00:41:48 12 stmt := 'DROP TABLE &&1';
00:41:48 13 dbms_sql.parse(c, stmt, DBMS_SQL.NATIVE);
00:41:48 14 fdbk := dbms_sql.execute(c);
00:41:48 15 dbms_sql.close_cursor(c);
00:41:48 16 dbms_output.put_line('Dropped TABLE [&&1].');
00:41:48 17 END LOOP;
00:41:48 18 END;
00:41:48 19 /
Enter value for 1: NOTEXISTS_TAB
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.07
00:46:20 SCOTT@orcl> UNDEFINE 1
00:46:23 SCOTT@orcl> /
Enter value for 1: EMP_BAK
Dropped TABLE [EMP_BAK].
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.27使用DBMS_SQL包来执行动态的DML语句
动态的DML语句经常作为字符串在运行时创建.
示例:
--注意dbms_application_info包的使用
01:02:36 SCOTT@orcl> EXEC dbms_application_info.set_client_info('CRY');
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.06
01:03:54 SCOTT@orcl> DECLARE
01:05:12 2 -- Define local DBMS_SQL variables, and open cursor.
01:05:12 3 c INTEGER := dbms_sql.open_cursor;
01:05:12 4 fdbk INTEGER;
01:05:12 5 stmt1 VARCHAR2(2000);
01:05:12 6 stmt2 VARCHAR2(20) := '-1'')';
01:05:12 7 -- V$SESSION.CLIENT_INFO variable.
01:05:12 8 client VARCHAR2(64);
01:05:12 9 BEGIN
01:05:12 10 stmt1 := 'INSERT INTO EMP_BAK(EMPNO,ENAME) VALUES ' || '( 123,''TEST_';
01:05:12 11 -- Get the current CLIENT_INFO value and conditionally append to string.
01:05:12 12 dbms_application_info.read_client_info(client);
01:05:12 13 IF client IS NOT NULL THEN
01:05:12 14 stmt1 := stmt1 || client || ''')';
01:05:12 15 ELSE
01:05:12 16 stmt1 := stmt1 || stmt2;
01:05:12 17 END IF;
01:05:12 18 DBMS_OUTPUT.put_line('stmt1:'||stmt1);
01:05:12 19 -- Build, parse, and execute SQL statement, then close cursor.
01:05:12 20 dbms_sql.parse(c, stmt1, dbms_sql.native);
01:05:12 21 fdbk := dbms_sql.execute(c);
01:05:12 22 dbms_sql.close_cursor(c);
01:05:12 23 dbms_output.put_line('Rows Inserted [' || fdbk || ']');
01:05:12 24 END;
01:05:13 25 /
stmt1:INSERT INTO EMP_BAK(EMPNO,ENAME) VALUES ( 123,'TEST_CRY')
Rows Inserted [1]
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.02使用BIND_VARIABLE来绑定标量,使用BIND_ARRAY来绑定嵌套表.
你也可以使用DBMS_SQL来执行PL/SQL块.
示例:
--使用DBMS_SQL来绑定变量
01:05:14 SCOTT@orcl> CREATE OR REPLACE PROCEDURE insert_empbak(empno number,
01:19:03 2 ename VARCHAR2,
01:19:03 3 deptno number := NULL) IS
01:19:03 4 -- Define local DBMS_SQL variables.
01:19:03 5 c INTEGER := dbms_sql.open_cursor;
01:19:03 6 fdbk INTEGER;
01:19:03 7 stmt VARCHAR2(2000);
01:19:03 8 -- Variable to get OUT parameter value.
01:19:03 9 client VARCHAR2(64);
01:19:03 10 BEGIN
01:19:03 11 stmt := 'INSERT INTO emp_bak(empno,ename,deptno) VALUES ( :empno,:ename,:deptno)';
01:19:03 12 -- Call and dynamically set the session for the CLIENT_INFO value.
01:19:03 13 dbms_application_info.read_client_info(client);
01:19:03 14 IF client IS NOT NULL THEN
01:19:03 15 client := client;
01:19:03 16 ELSE
01:19:03 17 client := '-1';
01:19:03 18 END IF;
01:19:03 19 -- Parse and execute the statement.
01:19:03 20 dbms_sql.parse(c, stmt, dbms_sql.native);
01:19:03 21 dbms_sql.bind_variable(c, 'empno', empno);
01:19:03 22 dbms_sql.bind_variable(c, 'ename', ename || client);
01:19:03 23 dbms_sql.bind_variable(c, 'deptno', deptno);
01:19:03 24 fdbk := dbms_sql.execute(c);
01:19:03 25 dbms_sql.close_cursor(c);
01:19:03 26 dbms_output.put_line('Rows Inserted [' || fdbk || ']');
01:19:03 27 END insert_empbak;
01:19:04 28 /
Procedure created.
Elapsed: 00:00:00.30
01:20:07 SCOTT@orcl> BEGIN INSERT_EMPBAK(321,'KING_',33); END;
01:20:21 2 /
Rows Inserted [1]
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.04
01:20:40 SCOTT@orcl> SELECT EMPNO,ENAME,DEPTNO FROM EMP_BAK WHERE DEPTNO=33;
EMPNO ENAME DEPTNO
---------- ---------- ----------
321 KING_CRY 33
1 row selected.
Elapsed: 00:00:00.00你应当注意在上面动态的DML语句中,已经没有单引号来界定传入的字符值了.
这是因为值和数据类型已经绑定到语句了.
--使用DBMS_SQL包处理返回一行数据的动态SELECT语句
01:46:08 SCOTT@orcl> DECLARE
01:50:49 2 c INTEGER := dbms_sql.open_cursor;
01:50:49 3 fdbk INTEGER;
01:50:49 4 statement VARCHAR2(2000);
01:50:49 5 v_s VARCHAR2(1) := 'S';
01:50:49 6 v_ename VARCHAR2(60);
01:50:49 7 v_empno number(4);
01:50:49 8 BEGIN
01:50:49 9 -- Build and parse SQL statement.
01:50:49 10 statement := 'SELECT empno, ename ' ||
01:50:49 11 'FROM emp_bak WHERE substr(ename,0,1) = :s AND ROWNUM=1';
01:50:49 12 dbms_output.put_line('statement:'||statement);
01:50:49 13 dbms_sql.parse(c, statement, dbms_sql.native);
01:50:49 14 -- Define column mapping, execute statement, and copy results.
01:50:49 15 dbms_sql.define_column(c, 1, v_empno); -- Define OUT mode variable.
01:50:49 16 dbms_sql.define_column(c, 2, v_ename, 60); -- Define OUT mode variable.
01:50:49 17 dbms_sql.bind_variable(c, 's', v_s); -- Bind IN mode variable.
01:50:49 18 fdbk := dbms_sql.execute_and_fetch(c);
01:50:49 19 dbms_sql.column_value(c, 1, v_empno); -- Copy query column to variable.
01:50:49 20 dbms_sql.column_value(c, 2, v_ename); -- Copy query column to variable.
01:50:49 21 -- Print return value and close cursor.
01:50:49 22 dbms_output.put_line('[' || v_empno || '][' || NVL(v_ename, 'None') || ']');
01:50:49 23 dbms_sql.close_cursor(c);
01:50:49 24 END;
01:50:50 25 /
statement:SELECT empno, ename FROM emp_bak WHERE substr(ename,0,1) = :s AND ROWNUM=1
[7369][SMITH]
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.06--使用DBMS_SQL包处理返回多行数据的动态SELECT语句
01:50:51 SCOTT@orcl> DECLARE
01:53:54 2 c INTEGER := dbms_sql.open_cursor;
01:53:54 3 fdbk INTEGER;
01:53:54 4 statement VARCHAR2(2000);
01:53:54 5 v_s VARCHAR2(1) := 'A';
01:53:54 6 v_ename VARCHAR2(60);
01:53:54 7 v_empno number(4);
01:53:54 8 BEGIN
01:53:54 9 -- Build and parse SQL statement.
01:53:54 10 statement := 'SELECT empno, ename ' ||
01:53:54 11 'FROM emp_bak WHERE substr(ename,0,1) = :s ';
01:53:54 12 dbms_output.put_line('statement:'||statement);
01:53:54 13 dbms_sql.parse(c, statement, dbms_sql.native);
01:53:54 14 -- Define column mapping, execute statement, and copy results.
01:53:54 15 dbms_sql.define_column(c, 1, v_empno); -- Define OUT mode variable.
01:53:54 16 dbms_sql.define_column(c, 2, v_ename, 60); -- Define OUT mode variable.
01:53:54 17 dbms_sql.bind_variable(c, 's', v_s); -- Bind IN mode variable.
01:53:54 18 fdbk := dbms_sql.execute(c);
01:53:54 19 LOOP
01:53:54 20 EXIT WHEN dbms_sql.fetch_rows(c) = 0;
01:53:54 21 dbms_sql.column_value(c, 1, v_empno); -- Copy query column to variable.
01:53:54 22 dbms_sql.column_value(c, 2, v_ename); -- Copy query column to variable.
01:53:54 23 -- Print return value and close cursor.
01:53:54 24 dbms_output.put_line('[' || v_empno || '][' || NVL(v_ename, 'None') || ']');
01:53:54 25 END LOOP;
01:53:54 26 dbms_sql.close_cursor(c);
01:53:54 27 END;
01:53:55 28 /
statement:SELECT empno, ename FROM emp_bak WHERE substr(ename,0,1) = :s
[7499][ALLEN]
[7876][ADAMS]
PL/SQL procedure successfully completed.
作者：edcvf3 发表于2013-6-8 2:01:52 原文链接
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