sql-如果不存在则插入 [英] sql - insert if not exists

问题描述

我在使用SQL查询时遇到麻烦.如果同一行尚不存在，我需要插入一行.这是我到目前为止的内容:

I am having trouble with a sql query. I need to insert a row if the same row does not exist already. This is what I have so far:

DECLARE
BEGIN
   FOR FOLDER_ROW IN (SELECT FOLDERID, USERID FROM DATA1.FOLDERS)
      LOOP                       
          IF NOT EXISTS (SELECT * FROM DATA1.FOLDER_USER WHERE FOLDER_ID = FOLDER_ROW.FOLDERID AND USER_ID = FOLDER_ROW.USERID) 
          INSERT INTO DATA1.FOLDER_USER (FOLDER_ID, USER_ID) VALUES (FOLDER_ROW.FOLDERID, FOLDER_ROW.USERID);
     END LOOP;
    COMMIT;
END;

我对sql不太熟悉，尤其是不存在的语法，因此在执行时会出现以下错误:

I would not be very familiar with sql particularly the not exists syntax so when I execute I get the following error:

ORA-06550:第37行，第11列:PLS-00103:出现符号 预期以下情况之一时，请输入"INSERT":

ORA-06550: line 37, column 11: PLS-00103: Encountered the symbol "INSERT" when expecting one of the following:

然后和或

用"then"代替"INSERT".

The symbol "then" was substituted for "INSERT" to continue.

ORA-06550: line 38, column 10:
PLS-00103: Encountered the symbol "LOOP" when expecting one of the following:

   if
ORA-06550: line 40, column 5:
PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following:

   end not pragma final instantiable order overriding static
   member constructor map

推荐答案

在SQL中完成所有操作，而不是将上下文切换到PL/SQL:

Do it all in SQL rather than context switching into PL/SQL:

INSERT INTO DATA1.FOLDERS
(folder_id,
 user_id)
SELECT f1.folder_id,
       f1.user_id
  FROM DATA1.FOLDERS f1
 WHERE NOT EXISTS (SELECT 1
                     FROM DATA1.FOLDERS f2
                    WHERE f1.folder_id = f2.folder_id
                      AND f1.user_id = f2.user_id);

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