This method has been studied for a long time, and it is not easy, huh, huh. . . . , and finally succeeded!
My understanding of the usage of executeimmediate is illustrated with an example. There is a stored procedure named: p_test, which has three parameters: two input parameters and one output parameter. The implementation process is as follows:
declare
v_sql varchar2(1000);
c varchar2(1000);
a varchar2(1) :='1';
b number :=1;
begin
-- of course, dynamic stored procedures can be implemented here, just put them directly into the variable v_sql (here is A specified procedure p_test)
v_sql:='begin p_test(:v1,:v2,:v3); end;';
executeimmediate v_sql using in '1',in '2',out c;
--or executeimmediate v_sql using ' 1', '2',out c;
dbms_output.put_line(c);
end;
Above we have implemented the calling method of dynamically passing parameters and dynamic stored procedures. It is worth noting that: the default is in, in can be saved, out cannot be saved!
Another point worth noting is that each dynamic (executeimmediate) method has its own begin.........end; just wrap it, if there are more than one, write it like this:
-- The first
begin
v_sql:='begin p_test1(:v1,:v2,:v3); end;';
executeimmediate v_sql using in '1',in '2',out c;
--or executeimmediate v_sql using '1' , '2',out c;
dbms_output.put_line(c);
end; --the
second
begin
v_sql:='begin p_test2(:v1,:v2,:v3); end;';
executeimmediate v_sql using in '1 ',in '2',out c;
--or executeimmediate v_sql using '1', '2',out c;
dbms_output.put_line(c);
end;
. . . . . . .
--Nth
begin
--end
;
EXECUTEIMMEDIATE代替了以前Oracle8i中DBMS_SQL package包.它解析并马上执行动态的SQL语句或非运行时创建的PL/SQL块.动态创建和执行SQL语句性能超前，EXECUTEIMMEDIATE的目标在于减小企业费用并获得较高的性能，较之以前它相当容易编码.尽管DBMS_SQL仍然可用，但是推荐使用EXECUTEIMMEDIATE,因为它获的收益在包之上。
使用技巧
1. EXECUTEIMMEDIATE将不会提交一个DML事务执行，应该显式提交
如果通过EXECUTEIMMEDIATE处理DML命令，那么在完成以前需要显式提交或者作为EXECUTEIMMEDIATE自己的一部分. 如果通过EXECUTEIMMEDIATE处理DDL命令,它提交所有以前改变的数据
2. 不支持返回多行的查询,这种交互将用临时表来存储记录(参照例子如下)或者用REF cursors.
3. 当执行SQL语句时，不要用分号，当执行PL/SQL块时，在其尾部用分号.
4. 在Oracle手册中，未详细覆盖这些功能。下面的例子展示了所有用到Executeimmediate的可能方面.希望能给你带来方便.
5. 对于Forms开发者,当在PL/SQL 8.0.6.3.版本中，Forms 6i不能使用此功能.
EXECUTEIMMEDIATE用法例子
1. 在PL/SQL运行DDL语句
begin
executeimmediate 'set role all';
end;
2. 给动态语句传值(USING 子句)
declare
l_depnam varchar2(20) := 'testing';
l_loc varchar2(10) := 'Dubai';
begin
executeimmediate 'insert into dept values (:1, :2, :3)'
using 50, l_depnam, l_loc;
commit;
end;
3. 从动态语句检索值(INTO子句)
declare
l_cnt varchar2(20);
begin
executeimmediate 'select count(1) from emp'
into l_cnt;
dbms_output.put_line(l_cnt);
end;
4. 动态调用例程.例程中用到的绑定变量参数必须指定参数类型.黓认为IN类型,其它类型必须显式指定
declare
l_routin varchar2(100) := 'gen2161.get_rowcnt';
l_tblnam varchar2(20) := 'emp';
l_cnt number;
l_status varchar2(200);
begin
executeimmediate 'begin ' || l_routin || '(:2, :3, :4); end;'
using in l_tblnam, out l_cnt, in out l_status;
if l_status != 'OK' then
dbms_output.put_line('error');
end if;
end;
5. 将返回值传递到PL/SQL记录类型;同样也可用%rowtype变量
declare
type empdtlrec is record (empno number(4),
ename varchar2(20),
deptno number(2));
empdtl empdtlrec;
begin
executeimmediate 'select empno, ename, deptno ' ||
'from emp where empno = 7934'
into empdtl;
end;
6. 传递并检索值.INTO子句用在USING子句前
declare
l_dept pls_integer := 20;
l_nam varchar2(20);
l_loc varchar2(20);
begin
executeimmediate 'select dname, loc from dept where deptno = :1'
into l_nam, l_loc
using l_dept ;
end;
7. 多行查询选项.对此选项用insert语句填充临时表，用临时表进行进一步的处理,也可以用REF cursors纠正此缺憾.
declare
l_sal pls_integer := 2000;
begin
executeimmediate 'insert into temp(empno, ename) ' ||
' select empno, ename from emp ' ||
' where sal > :1'
using l_sal;
commit;
end;
对于处理动态语句,EXECUTEIMMEDIATE比以前可能用到的更容易并且更高效.当意图执行动态语句时，适当地处理异常更加重要.应该关注于捕获所有可能的异常.
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