Psycopg2：如何使用带有 python 的 psycopg2 插入和更新冲突？

Question

我正在使用 psycopg2 向 postgres 数据库插入命令，当出现冲突时，我只想更新其他列值。

这里是查询：

        insert_sql = '''
        INSERT INTO tablename (col1, col2, col3,col4)
        VALUES (%s, %s, %s, %s) (val1,val2,val3,val4)
        ON CONFLICT (col1)
        DO UPDATE SET
        (col2, col3, col4)
        = (val2, val3, val4) ; '''

        cur.excecute(insert_sql)

我想找出我哪里做错了？我使用的变量 val1 , val2, val3 不是实际值。

Answer 1

尝试：

INSERT INTO tablename (col1, col2, col3,col4)
        VALUES (val1,val2,val3,val4)
        ON CONFLICT (col1)
        DO UPDATE SET
        (col2, col3, col4)
        = (val2, val3, val4) ; '''

Answer 2

引用psycopg2的documentation：

警告永远，永远，永远不要使用 Python 字符串连接 (+) 或字符串参数插值 (%) 将变量传递给 SQL 查询字符串。甚至没有在枪口下。

现在，对于更新插入操作，您可以这样做：

insert_sql = '''
    INSERT INTO tablename (col1, col2, col3, col4)
    VALUES (%s, %s, %s, %s)
    ON CONFLICT (col1) DO UPDATE SET
    (col2, col3, col4) = (EXCLUDED.col2, EXCLUDED.col3, EXCLUDED.col4);
'''
cur.execute(insert_sql, (val1, val2, val3, val4))

请注意，查询的参数作为元组传递给 execute 语句（这确保 psycopg2 将负责调整它们以适应 SQL同时保护你免受注入攻击）。

EXCLUDED 位允许您重复使用这些值，而无需在数据参数中指定它们两次。

Answer 3

这里的函数接受 df、[=20= 的模式名称]、[=20= 的名称]、您要在冲突名称中用作冲突的列以及创建的引擎来自 sqlalchemy 的 create_engine。它更新了关于冲突列的 table。这是@Ionut Ticus 解决方案的扩展解决方案。不要一起使用 pandas.to_sql() 。 pandas.to_sql() 破坏主键设置。在这种情况下，需要通过 ALTER 查询设置主键，这是下面函数的建议。主键不一定被pandas销毁，一个可能没有被设置。在这种情况下会出现错误：没有匹配给定键的唯一约束以供引用 table？函数会建议你执行下面的操作。

engine.execute('ALTER TABLE {schemaname}.{tablename} ADD PRIMARY KEY ({conflictcolumn});

函数：

def update_query(df,schemaname,tablename,conflictcolumn,engine ):
"""
This function takes dataframe as df, name of schema as schemaname,name of the table to append/add/insert as tablename, 
and column name that only  other elements of rows will be changed if it's existed as conflictname,
database engine as engine.
Example to engine : engine_portfolio_pg = create_engine('postgresql://pythonuser:vmqJRZ#dPW24d@145.239.121.143/cetrm_portfolio')
Example to schemaname,tablename : weatherofcities.sanfrancisco , schemaname = weatherofcities, tablename = sanfrancisco.

"""


excluded = ""
columns = df.columns.tolist()
deleteprimary = columns.copy()
deleteprimary.remove(conflictcolumn)
excluded = ""
replacestring = '%s,'*len(df.columns.tolist())
replacestring = replacestring[:-1]

for column in deleteprimary:
    excluded += "EXCLUDED.{}".format(column)+","
excluded = excluded[:-1]

columns = ','.join(columns)

deleteprimary  = ','.join(deleteprimary)

insert_sql = """ INSERT INTO {schemaname}.{tablename} ({allcolumns})
    VALUES ({replacestring})
    ON CONFLICT ({conflictcolumn}) DO UPDATE SET
    ({deleteprimary}) = ({excluded})""".format( tablename = tablename, schemaname=schemaname,allcolumns = columns, replacestring= replacestring,
                                               conflictcolumn= conflictcolumn,deleteprimary = deleteprimary,  excluded=excluded  )



conn = engine.raw_connection()
conn.autocommit = True

#conn = engine.connect()

cursor = conn.cursor()

i = 0
print("------------------------"*5)

print("If below error happens:")
print("there is no unique constraint matching given keys for referenced table?")    
print("Primary key is not set,you can execute:")
print("engine.execute('ALTER TABLE {}.{} ADD PRIMARY KEY ({});')".format(schemaname,tablename,conflictcolumn))
print("------------------------"*5)
for index, row in df.iterrows():

    cursor.execute(insert_sql, tuple(row.values))
    conn.commit() 
    if i == 0:
        print("Order of Columns in Operated SQL Query for Rows")
        columns = df.columns.tolist()
        print(insert_sql%tuple(columns))
        print("----")
        print("Example of Operated SQL Query for Rows")
        print(insert_sql%tuple(row.values))
        print("---")
        
    i += 1 

conn.close()

Answer 4

使用：

INSERT INTO members (member_id, customer_id, subscribed, customer_member_id, phone, cust_atts) VALUES (%s, %s, %s, %s, %s, %s) ON CONFLICT (customer_member_id) DO UPDATE SET (phone) = (EXCLUDED.phone);

我收到以下错误：

psycopg2.errors.FeatureNotSupported: source for a multiple-column UPDATE item must be a sub-SELECT or ROW() expression
LINE 1: ...ICT (customer_member_id) DO UPDATE SET (phone) = (EXCLUDED.p...

更改为：

INSERT INTO members (member_id, customer_id, subscribed, customer_member_id, phone, cust_atts) VALUES (%s, %s, %s, %s, %s, %s) ON CONFLICT (customer_member_id) DO UPDATE SET (phone) = ROW(EXCLUDED.phone);

问题已解决。

Psycopg2：如何使用带有 python 的 psycopg2 插入和更新冲突？

Psycopg2: how to insert and update on conflict using psycopg2 with python?

postgresql

psycopg2