oracle对动态sql语句的处理

1、静态SQL语句性能优于动态SQL语句，如果功能确定最好使用静态SQL语句

2、使用execute immediate语句，用于处理除了多行查询之外的任何动态SQL，包括DDL、DCL、DML、以及单行Select语句

3、使用动态引用游标OPEN-FOR、FETCH、CLOSE语句处理多行查询语句

4、使用批量的动态SQL语句，可以提高pl/sql性能

一、处理DDL语句

begin
declare
v_sql varchar2(2000);
begin
v_sql:='create table test as select * from dept';
execute immediate v_sql;
end;
end;

二、处理DCL语句

begin
declare
v_sql varchar2(2000);
begin
v_sql:='grant select on test to user_01';
execute immediate v_sql;
end;
end;

三、处理DML语句

根据DML语句是否有占位符、是否是returning子句处理方式不同

1、处理无占位符和returning子句的DML语句

begin
declare
v_sql varchar2(2000);
begin
v_sql:='update test set loc=''HELLOWORLD'' where deptno=10';
execute immediate v_sql;
end;
end;

2、处理有占位符无returning子句的DML语句

begin
declare
v_sql varchar2(2000);
begin
v_sql:='update test set loc=:loc where deptno=:deptno';
execute immediate v_sql using &1,&2;
end;
end;

3、处理无占位符有returning子句的DML语句

begin
declare
v_sql varchar2(2000);
v_dname dept.dname%type;
begin
v_sql:='update test set loc=''HELLOWORLD'' where deptno=10 returning dname into :name';
execute immediate v_sql returning into v_dname;
dbms_output.put_line(v_dname||'被更新');
end;
end;

4、处理含占位符有returning子句的DML语句

begin
declare
v_sql varchar2(2000);
v_dname dept.dname%type;
begin
v_sql:='update test set loc=''HELLOWORLD'' where deptno=:deptno returning dname into :name';
execute immediate  v_sql using &deptno returning into v_dname;
dbms_output.put_line(v_dname||'被更新');
end;
end;

四、处理单行查询

begin
declare
v_sql varchar2(2000);
v_record dept%rowtype;
begin
v_sql:='select * from dept where deptno=:deptno';
execute immediate v_sql into v_record using &deptno ;
dbms_output.put_line('部门名称：'||v_record.dname);
end;
end;

通过记录变量来获取数据

五、处理多行查询

begin
declare
type dept_cur is ref cursor;
c_dept dept_cur;
v_sql varchar2(2000);
v_record dept%rowtype;
begin
v_sql:='select * from dept where deptno=:deptno';
open c_dept for v_sql using &deptno;
loop
fetch c_dept into v_record;
exit when c_dept%NOTFOUND;
dbms_output.put_line('部门名称：'||v_record.dname);
end loop;
close c_dept;
end;
end;

六、在动态SQL语句中使用批量绑定

在动态SQL语句中使用批量绑定，可以加快批量数据的处理速度，提高性能；

当使用批量绑定时，集合元素要使用SQL的数据类型而非PL/SQL数据类型，最好通过%TYPE,%ROWTYPE来

（1）、在动态DML语句上面使用批量绑定

语法：

FORALL index IN 1..v_tab.count
execute immediate v_sql using v_tab(i);

举例：

begin
declare
type dept_var is varray(3) of dept.deptno%type;
v_dept dept_var;
v_sql varchar2(2000);
begin
v_dept:=dept_var(1,2,3);
v_sql:='update dept set loc=''测试数据'' where deptno=:deptno';
forall i IN 1..v_dept.count
execute immediate v_sql using v_dept(i) ;
end;
end;

（2）、在DML返回子句上使用批量绑定

语法：

execute immediate v_sql
returning bulk collect into v_coll;

举例：

begin
declare
type dname_tab is table of dept.dname%type;
v_name dname_tab;
type loc_tab is table of dept.loc%type;
v_loc loc_tab;
v_sql varchar2(2000);
begin
v_sql:='update dept set loc=''测试数据DDDDD'' where deptno=:deptno returning dname,loc into :1,:2';
execute immediate v_sql using &deptno returning bulk collect into v_name,v_loc;
for i IN 1..v_name.count loop
dbms_output.put_line('部门名称：'||v_name(i)||'  地址：'||v_loc(i));
end loop;
end;
end;

（3）、在execute immediate语句上使用批量绑定查询语句

语法：

execute immediate v_sql bulk collect into v_coll;

举例：

begin
declare
type dname_tab is table of dept.dname%type;
v_name dname_tab;
type loc_tab is table of dept.loc%type;
v_loc loc_tab;
v_sql varchar2(2000);
begin
v_sql:='select dname,loc from dept where deptno=:deptno';
execute immediate v_sql bulk collect into v_name,v_loc using &deptno;
for i IN 1..v_name.count loop
dbms_output.put_line('部门名称：'||v_name(i)||'  地址：'||v_loc(i));
end loop;
end;
end;

（4）、在游标FETCH语句中使用批量提取

语法：

fetch v_cursor bulk collect into v_coll;

举例：

begin
declare
type c_ref is ref cursor;
c_dept c_ref;
type dname_tab is table of dept.dname%type;
v_name dname_tab;
type loc_tab is table of dept.loc%type;
v_loc loc_tab;
v_sql varchar2(2000);
begin
v_sql:='select dname,loc from dept where deptno=:deptno';
open c_dept for v_sql using &deptno;
fetch c_dept bulk collect into v_name,v_loc;
close c_dept;

for i IN 1..v_name.count loop
dbms_output.put_line('部门名称：'||v_name(i)||'  地址：'||v_loc(i));
end loop;
end;
end;