动态sql（dbms_sql包的使用）

1、执行诸如DDL和DDL语句（select除外)

a)打开一个游标

b)分析要执行的语句

c)绑定可能需要的任何输入变量

d)执行语句

e)关闭游标


select语句的执行如下：


set serveroutput on;


declare


v_cursorid number;


v_selectrecords varchar2(500);


v_numrows integer;


v_mynum integer;


v_mytext varchar(50);


begin


v_cursorid := dbms_sql.open_cursor;


v_selectrecords := 'select * from mytable';


dbms_sql.parse(v_cursorid,v_selectrecords,dbms_sql.native);


dbms_sql.define_column(v_cursorid,1,v_mynum);


dbms_sql.define_column(v_cursorid,2,v_mytext,50);


v_numrows := dbms_sql.execute(v_cursorid);


loop


if dbms_sql.fetch_rows(v_cursorid)=0 then exit;


end if;


dbms_sql.column_value(v_cursorid,1,v_mynum);


dbms_sql.column_value(v_cursorid,2,v_mytext);


dbms_output.put_line(v_mynum||' '||v_mytext);


end loop;




dbms_sql.close_cursor(v_cursorid);


end;


/

2、select查询的动态sql实现

a)打开一个游标

b)分析要执行的语句

c)绑定可能需要的任何输入变量（如果需要）

4)定义输出变量

d)执行语句

5)取回记录

6)将取回的记录结果存储在pl/sql变量中

e)关闭游标


create语句的例子如下


declare


v_cursorid number;


v_createTableString varchar2(500);


v_numrows integer;


begin


v_cursorid := dbms_sql.open_cursor;


v_createTableString := 'create table mytable(myrow integer,mydesc varchar2(50)) tablespace tabs';


dbms_sql.parse(v_cursorid,v_createTableString,dbms_sql.native);


v_numrows := dbms_sql.execute(v_cursorid);


exception


when others then


if sqlcode!=-955 then raise;


else


dbms_output.put_line('talbe already exists');


end if;


dbms_sql.close_cursor(v_cursorId);


end;


/


insert语句的例子如下


set serveroutput on;


declare


v_cursorid number;


v_insertRecords varchar2(500);


v_numrows integer;


begin


v_cursorid := dbms_sql.open_cursor;


v_insertRecords := 'insert into mytable values(:mynum,:mytext)';


dbms_sql.parse(v_cursorid,v_insertrecords,dbms_sql.native);


dbms_sql.bind_variable(v_cursorid,':mynum',1);


dbms_sql.bind_variable(v_cursorid,':mytext','one');


v_numrows := dbms_sql.execute(v_cursorId);


dbms_output.put_line(v_numrows);




--di 2 tiao ji lu


dbms_sql.bind_variable(v_cursorid,':mynum',2);


dbms_sql.bind_variable(v_cursorid,':mytext','two');


v_numrows := dbms_sql.execute(v_cursorId);


dbms_output.put_line(v_numrows||'2');


exception


when others then raise;


dbms_sql.close_cursor(v_cursorid);


commit;


end;


/

3、执行pl/sql匿名块

a)打开一个游标

b)分析要执行的语句

c)绑定可能需要的任何输入变量（如果需要）

d)执行语句

5)取回记录

6)将取回的记录结果存储在pl/sql变量中

e)关闭游标


执行匿名块


set serveroutput on;


declare


v_cursorid number;


v_matchrecord varchar2(500);


v_numrows integer;


v_mynum integer;


v_mytext varchar2(50);


begin


v_cursorid := dbms_sql.open_cursor;


v_matchrecord := 'begin


select myrow,mydesc into :myrow ,:mytext from mytable


where myrow = 2;


end;';


dbms_sql.parse(v_cursorid,v_matchrecord,dbms_sql.native);


dbms_sql.bind_variable(v_cursorid,':myrow',v_mynum);


dbms_sql.bind_variable(v_cursorid,':mytext',v_mytext,50);


v_numrows := dbms_sql.execute(v_cursorid);


dbms_sql.variable_value(v_cursorid,':myrow',v_mynum);


dbms_sql.variable_value(v_cursorid,':mytext',v_mytext);




dbms_output.put_line(v_mynum||' '||v_mytext);




dbms_sql.close_cursor(v_cursorid);


end;


/


检查取回记录的进度


set serveroutput on;


declare


v_cursorid number;


v_matchrecord varchar2(500);


v_numrows integer;


v_mynum integer;


v_mytext varchar2(50);




v_myrowid rowid;


v_totrow integer;


begin


v_cursorid := dbms_sql.open_cursor;


v_matchrecord := 'select * from mytable for update';


dbms_sql.parse(v_cursorid,v_matchrecord,dbms_sql.native);




dbms_sql.define_column(v_cursorid,1,v_mynum);


dbms_sql.define_column(v_cursorid,2,v_mytext,50);




v_numrows := dbms_sql.execute(v_cursorid);




loop


if dbms_sql.fetch_rows(v_cursorid)=0 then exit;


end if;




v_totrow := dbms_sql.last_row_count;


v_myrowid := dbms_sql.last_row_id;


dbms_output.put_line('the last row count is:'||v_totrow||


' the last rowid is:'||v_myrowid);




dbms_sql.column_value(v_cursorid,1,v_mynum);


dbms_sql.column_value(v_cursorid,2,v_mytext);


dbms_output.put_line(v_mynum||' '||v_mytext);


end loop;








dbms_sql.close_cursor(v_cursorid);


end;


/