练习七 Procedure中使用DDL

1 在存储过程中使用ddl语句有如下异常:

create or replace procedure test_create_table
(Table_Name  in VARCHAR2,
 column_name1 in varchar2,
 column_name2 in varchar2,
 column_name3 in varchar2,
 column_type in varchar2) as
  /*修改某个表的表结构*/
begin
  create table  Table_Name(

         column_name1 column_type,
         column_name2 column_type,
         column_name3 column_type
  );
end test_create_table;

Compilation errors for PROCEDURE CICI.TEST_CREATE_TABLE

Error: PLS-: 出现符号 "CREATE"在需要下列之一时：
        ( begin
          case declare exit for goto if loop mod null pragma raise
          return select update while with <an identifier>
          <a double-quoted delimited-identifier> <a bind variable> <<
          continue close current delete fetch lock insert open rollback
          savepoint set sql execute commit forall merge pipe purge
Line:
Text: create table  Table_Name(

Compilation errors for PROCEDURE CICI.TEST_CREATE_TABLE

Error: PLS-: 出现符号 "CREATE"在需要下列之一时：
        ( begin
          case declare exit for goto if loop mod null pragma raise
          return select update while with <an identifier>
          <a double-quoted delimited-identifier> <a bind variable> <<
          continue close current delete fetch lock insert open rollback
          savepoint set sql execute commit forall merge pipe purge
Line:
Text: create table  Table_Name(

2 将DML封装存入string中

create or replace procedure Modify_Table_Structure as
  Pstring_droptable   varchar2(2000);
  Pstring_createtable varchar2(2000);
  Pstring_deletetable varchar2(2000);
  Pstring_altertable  varchar2(2000);
  pstring_inserttable varchar2(2000);
  v_count integer;
begin
  Pstring_droptable   := 'drop table  CONTRACT_KANGJIA_BACK';
  Pstring_createtable := 'create table CONTRACT_KANGJIA_BACK  as select *　from  CONTRACT_KANGJIA ';
  Pstring_deletetable := 'delete from  CONTRACT_KANGJIA';
  Pstring_altertable  := 'alter table CONTRACT_KANGJIA modify sell_money  number(10,5)';
  pstring_inserttable := 'insert into CONTRACT_KANGJIA (id, busiman_name, sell_date, product_type, sell_money)  select  id, busiman_name, sell_date, product_type, sell_money
    from CONTRACT_KANGJIA_BACK';

  select count(*)
    into v_count
    from user_tables
   where table_name = 'CONTRACT_KANGJIA_BACK';
   dbms_output.put_line('v_count   1 '||v_count);
  if (v_count > 0) then
    execute immediate Pstring_droptable;
     dbms_output.put_line('v_count   2 '||v_count);
  end if;

  execute immediate Pstring_createtable;
  execute immediate Pstring_deletetable;
  execute immediate Pstring_altertable;
  execute immediate pstring_inserttable;
  execute immediate Pstring_droptable;
end;

3 进一步提炼.将表名称提取成变量名称

create or replace procedure Modify_Table_Structure(table_name in varchar2) as
  Pstring_droptable   varchar2(2000);
  Pstring_createtable varchar2(2000);
  Pstring_deletetable varchar2(2000);
  Pstring_altertable  varchar2(2000);
  pstring_inserttable varchar2(2000);
  v_count integer;
begin
  Pstring_droptable   := 'drop table  '||table_name||'_BACK';
  Pstring_createtable := 'create table '||table_name||'_BACK  as select *　from '||table_name;
  Pstring_deletetable := 'delete from '||table_name;
  Pstring_altertable  := 'alter table '||table_name|| '  modify sell_money  number(10,5)';
  pstring_inserttable :=
   'insert into '||table_name|| ' (id, busiman_name, sell_date, product_type, sell_money)
   select  id, busiman_name, sell_date, product_type, sell_money
    from  '||table_name||'_BACK' ;

  select count(*)
    into v_count
    from user_tables
   where table_name = 'table_name'||'_BACK';
   dbms_output.put_line('v_count   1 '||v_count);
  if (v_count > 0) then
    execute immediate Pstring_droptable;
     dbms_output.put_line('v_count   2 '||v_count);
  end if;
 dbms_output.put_line(Pstring_droptable);
  dbms_output.put_line(Pstring_createtable);
   dbms_output.put_line(Pstring_deletetable);
    dbms_output.put_line(Pstring_altertable);
    dbms_output.put_line(pstring_inserttable);
  execute immediate Pstring_createtable;
  execute immediate Pstring_deletetable;
  execute immediate Pstring_altertable;
  execute immediate pstring_inserttable;
  execute immediate Pstring_droptable;
end;

4 执行成功！

call Modify_Table_Structure('contract_kangjia');