Oracle drop if exists

参考https://stackoverflow.com/questions/1799128/oracle-if-table-exists

我的官方博客http://blog.alei.tech ，转载请注明。网页地址https://alei.tech/2016/08/12/%E5%9C%A8Oracle%E6%95%B0%E6%8D%AE%E4%B8%AD%E5%AF%BB%E6%89%BE%E4%B8%80%E4%B8%AA%E5%80%BC/

场景

• 删除表，视图等对象时，静默执行，不返回报错信息
• 类似dorp table if exists，语句可反复执行
• 开发人员编写sql，让实施人员执行
• 直接写drop table abc，如果abc表已经被删除或者不存在，返回报错信息，对于不懂sql的实施人员来说，会产生干扰

代码示例

创建存储过程

• 适用于drop table, procedure, function, trigger, view, sequence

  create or replace procedure dropObject(ObjName varchar2,ObjType varchar2)
  is
   v_counter number := 0;   
  begin    
    if upper(ObjType) = 'TABLE' then
      select count(*) into v_counter from user_tables where table_name = upper(ObjName);
      if v_counter > 0 then          
        execute immediate 'drop table ' || ObjName || ' cascade constraints';        
      end if;   
    end if;
    if upper(ObjType) = 'PROCEDURE' then
      select count(*) into v_counter from User_Objects where object_type = 'PROCEDURE' and OBJECT_NAME = upper(ObjName);
        if v_counter > 0 then          
          execute immediate 'DROP PROCEDURE ' || ObjName;        
        end if; 
    end if;
    if upper(ObjType) = 'FUNCTION' then
      select count(*) into v_counter from User_Objects where object_type = 'FUNCTION' and OBJECT_NAME = upper(ObjName);
        if v_counter > 0 then          
          execute immediate 'DROP FUNCTION ' || ObjName;        
        end if; 
    end if;
    if upper(ObjType) = 'TRIGGER' then
      select count(*) into v_counter from User_Triggers where TRIGGER_NAME = upper(ObjName);
        if v_counter > 0 then          
          execute immediate 'DROP TRIGGER ' || ObjName;
        end if; 
    end if;
    if upper(ObjType) = 'VIEW' then
      select count(*) into v_counter from User_Views where VIEW_NAME = upper(ObjName);
        if v_counter > 0 then          
          execute immediate 'DROP VIEW ' || ObjName;        
        end if; 
    end if;
    if upper(ObjType) = 'SEQUENCE' then
      select count(*) into v_counter from user_sequences where sequence_name = upper(ObjName);
        if v_counter > 0 then          
          execute immediate 'DROP SEQUENCE ' || ObjName;        
        end if; 
    end if;
  end;
  

使用存储过程

• 创建temp_table表之前，判断，if exists then drop
• 此语句示例在pl/sql developer中执行
• ”/”必须在行首，之前不能有空格

  begin
    dropObject('temp_table','table');
  end;
  /
  create table