Oracle

Question

如果主 table 的 ID 已经存在，我想删除 Oracle 数据库中的几行：我试着先做一个 SELECT 来检查主 table 中是否存在 ID，然后根据其他 tables:

中的 ID 删除行

DECLARE
    PROJECT_ID PLS_INTEGER;
    PROJECT_ID_TO_DELETE PLS_INTEGER;
BEGIN
    PROJECT_ID := PROJECTS_SEQ.nextval; 
    SELECT PROJ_ID INTO PROJECT_ID_TO_DELETE FROM PROJECTS WHERE PROJ_NAME_EN LIKE 'FD Project - CSB - A.1 - CFT - Final Reject of an Increase Movement - Seb';    
    IF PROJECT_ID_TO_DELETE IS NULL THEN
        DELETE FROM PROJECTS_ORG WHERE PROJ_ID = PROJECT_ID_TO_DELETE;
        DELETE FROM PROJECTS WHERE PROJ_ID  = PROJECT_ID_TO_DELETE;
        DELETE FROM MVT_ONGOING WHERE MVT_ONGOING_PROJ_ID  = PROJECT_ID_TO_DELETE;
        DELETE FROM MVT_HISTORY WHERE MVT_HISTORY_PROJ_ID  = PROJECT_ID_TO_DELETE;
    END IF;
    Insert into PROJECTS (PROJ_ID, ...) values (PROJECT_ID, ...);
    Insert into PROJECTS_ORG (PROJ_ID, ...) values (PROJECT_ID, ...);
    Insert into MVT_ONGOING (MVT_ONGOING_PROJ_ID, ...);
    Insert into MVT_HISTORY (PROJ_ID, ...) values (PROJECT_ID, ...);
END;

我收到错误消息“找不到数据”

能否请您帮助我找到最佳优化解决方案？

谢谢

Answer 1

像这样：

DECLARE
   project_id_new        PLS_INTEGER;
   project_id_to_delete  PLS_INTEGER;
BEGIN
   BEGIN
      SELECT proj_id
        INTO project_id_to_delete
        FROM projects
       WHERE proj_name_en LIKE 'blabla';

      DELETE FROM projects_org WHERE proj_id = project_id_to_delete;
      DELETE FROM projects     WHERE proj_id = project_id_to_delete;
      DELETE FROM mvt_ongoing  WHERE mvt_ongoing_proj_id = project_id_to_delete;
      DELETE FROM mvt_history  WHERE mvt_history_proj_id = project_id_to_delete;
   EXCEPTION
      WHEN NO_DATA_FOUND
      THEN
         NULL;
   END;

   project_id_new := seq.nextval;
   
   INSERT INTO projects (project_id)     VALUES (project_id_new);
   INSERT INTO projects_org (project_id) VALUES (project_id_new);
END;

它有什么作用？

试图找到 PROJ_ID
如果找到它，则执行 DELETEs
- 您不必使用 IF；如果找到，就会知道。如果未找到，则引发异常
否则，NO_DATA_FOUND 引发异常并处理
- 我选择什么都不做，你可能想做其他事情

插入时（正如您评论的那样，您希望始终这样做）：将删除部分包含在它自己的 BEGIN-EXCEPTION-END 块中，以便处理可能的 no_data_found 错误。然后，找到 project_id_new 值（例如，使用序列）并在 INSERT 语句中使用它。

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