[英]How to check a row already exists before copying the data from csv to postgres using python
我嘗試使用python將多個文件中的csv數據轉儲到postgres中,我成功完成了,但是我想在復制到數據庫postgres中之前檢查特定行是否已經存在。請檢查我的代碼
SQL_STATEMENT = """
COPY %s FROM STDIN WITH
CSV
HEADER
DELIMITER AS ','
"""
def process_file(conn, table_name, file_object):
cursor = conn.cursor()
cursor.
cursor.copy_expert(sql=SQL_STATEMENT % table_name, file=file_object)
conn.commit()
cursor.close()
connection = psycopg2.connect("dbname=dataflow user=postgres host=localhost password=root")
try:
process_file(connection, 'mytable', f)
finally:
connection.close()
請建議我該怎么做。
COPY
只是將格式正確的數據加載到表中-無需預處理。 因此,您可以將csv復制到臨時表,然后跳過現有表將行插入到表中:
CREATE TABLE temp_t AS SELECT * FROM table_name WHERE false
;
COPY temp_t FROM STDIN WITH
CSV
HEADER
DELIMITER AS ','
;
INSERT INTO table_name
SELECT *
FROM temp_t
EXCEPT
SELECT *
FROM table_name
;
https://www.postgresql.org/docs/current/static/sql-copy.html
COPY FROM將數據從文件復制到表(將數據追加到表中已有的任何內容)
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