Question

我想在Oracle中检查一个特定的表存在，哪种方式更通用和适当，我有下面列出的两种方法，如果表存在，方法1运行速度快，因为它只运行一个sql

处理异常并了解它。

create or replace procedure get_id_only (id out number) as
begin
execute immediate 'SELECT id FROM TABLE_NAME where rownum = 1' into id;
exception    
    when others then
      if (sqlcode = -942) then
        SELECT id into id FROM my_another_table;
      else 
        raise;
      end if;
end;

检查用户表以查看它是否存在。

create or replace procedure get_id_only (id out number) as
 count number;
begin
  SELECT count(*) into count FROM user_tables 
       WHERE table_name = 'TABLE_NAME';
  if (count = 0) then
    SELECT id into id FROM my_another_table;
    return;
  end if;

  execute immediate 'SELECT id FROM TABLE_NAME where rownum = 1' into id;

end;

Answer 1

正如你所说，第一个是最好和最有效的方式。因为捕获“table not found”异常：这避免了检查表是否存在两次的开销;

哪种方式适合检查表的存在

1 个答案: