Question

我正在尝试从CSV文件导入单词。它的一些记录已经在表格中。我的查询如下：

COPY words(word,definition,category) FROM '/home/username/Downloads/New1Names.csv' DELIMITER ',' CSV;

Word列是唯一的。如果出现重复，我会收到错误，如下所示：

ERROR:  duplicate key value violates unique constraint "words_word_u"
DETAIL:  Key (word)=(johnson) already exists.
CONTEXT:  COPY words, line 1: "word definition is here,male"

Answer 1

更新：您可以这样做

-- begin a transaction
BEGIN;
-- create a temporary table based on a factual table `words`
CREATE TEMP TABLE words_temp AS
SELECT word, definition, category 
  FROM words 
  WITH NO DATA
-- import data from the file into the temporary table
COPY words(word,definition,category) 
FROM '/home/username/Downloads/New1Names.csv' DELIMITER ',' CSV;  
-- prevent other concurrent writer processes to make changes while allowing to select from it
LOCK TABLE words IN EXCLUSIVE MODE;
-- insert from temporary into factual table only words that don't yet exist
INSERT INTO words(word,definition,category)
SELECT word,definition,category 
  FROM words_temp t 
 WHERE NOT EXISTS
(
  SELECT * 
    FROM words 
   WHERE word = t.word
);
-- commit the transaction and release the lock
COMMIT;

如果它重复，怎么说postgres忽略单词？

1 个答案: