我需要将大量的csv文件加载到PostgreSQL数据库中。我有一个名为source_files
的表格,其中包含文件路径和标志,指示是否已经加载了所有需要加载的csv文件。
我编写了以下代码,可以正确加载第一个文件,但随后抛出错误:
ERROR: 游标“curs”不存在
为什么会出现这个错误,我该如何解决?
DO $$
DECLARE
file_record record;
curs CURSOR
FOR SELECT id, file_path
FROM source_files
WHERE added_to_db=FALSE
ORDER BY id;
BEGIN
OPEN curs;
LOOP
-- Get next entry in source file which contains name of csv to load
FETCH curs INTO file_record;
exit WHEN NOT found;
BEGIN
-- As we need to add a column to the data after loading csv but before inserting
-- into final table we use a temporary table mytemp
DROP TABLE mytemp;
CREATE TABLE mytemp
(
dataA numeric,
dataB numeric
);
-- Load csv file
EXECUTE FORMAT('COPY mytemp
FROM ''%s''
DELIMITER '',''
CSV HEADER;', file_record.file_path);
-- Add Column specifying what source file the data is from
ALTER TABLE mytemp
ADD COLUMN source_id int;
UPDATE mytemp
SET source_id=file_record.id;
-- Add the data to the destination table
INSERT INTO data_table(
dataA,
dataB,
source_id
)
SELECT
mytemp.dataA,
mytemp.dataB
mytemp.source_id
FROM
mytemp
-- Set a flag to indicate that the current file in source_files has been loaded
UPDATE source_files
SET added_to_db=TRUE WHERE CURRENT OF curs;
COMMIT;
END;
END LOOP;
CLOSE curs;
END $$;