我需要用一个查询插入多行(行数不是常量)，所以我需要像这样执行查询:
INSERT INTO t (a, b) VALUES (1, 2), (3, 4), (5, 6);
我唯一知道的办法就是
args = [(1,2), (3,4), (5,6)]
args_str = ','.join(cursor.mogrify("%s", (x, )) for x in args)
cursor.execute("INSERT INTO t (a, b) VALUES "+args_str)
但我想要更简单的方法。
当前回答
执行任意接受数组的元组
https://www.postgresqltutorial.com/postgresql-python/insert/
""" array of tuples """
vendor_list = [(value1,)]
""" insert multiple vendors into the vendors table """
sql = "INSERT INTO vendors(vendor_name) VALUES(%s)"
conn = None
try:
# read database configuration
params = config()
# connect to the PostgreSQL database
conn = psycopg2.connect(**params)
# create a new cursor
cur = conn.cursor()
# execute the INSERT statement
cur.executemany(sql,vendor_list)
# commit the changes to the database
conn.commit()
# close communication with the database
cur.close()
except (Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if conn is not None:
conn.close()
其他回答
从@ant32
def myInsertManyTuples(connection, table, tuple_of_tuples):
cursor = connection.cursor()
try:
insert_len = len(tuple_of_tuples[0])
insert_template = "("
for i in range(insert_len):
insert_template += "%s,"
insert_template = insert_template[:-1] + ")"
args_str = ",".join(
cursor.mogrify(insert_template, x).decode("utf-8")
for x in tuple_of_tuples
)
cursor.execute("INSERT INTO " + table + " VALUES " + args_str)
connection.commit()
except psycopg2.Error as e:
print(f"psycopg2.Error in myInsertMany = {e}")
connection.rollback()
来自Psycopg2教程页面Postgresql.org的一个片段(见底部):
我想向您展示的最后一项是如何使用字典插入多行。如果你有以下情况:
namedict = ({"first_name":"Joshua", "last_name":"Drake"},
{"first_name":"Steven", "last_name":"Foo"},
{"first_name":"David", "last_name":"Bar"})
你可以很容易地将这三行都插入到字典中:
cur = conn.cursor()
cur.executemany("""INSERT INTO bar(first_name,last_name) VALUES (%(first_name)s, %(last_name)s)""", namedict)
它没有节省多少代码，但它确实看起来更好。
如果您正在使用SQLAlchemy，则不需要手工制作字符串，因为SQLAlchemy支持为单个INSERT语句生成多行VALUES子句:
rows = []
for i, name in enumerate(rawdata):
row = {
'id': i,
'name': name,
'valid': True,
}
rows.append(row)
if len(rows) > 0: # INSERT fails if no rows
insert_query = SQLAlchemyModelName.__table__.insert().values(rows)
session.execute(insert_query)
最后，在SQLalchemy1.2版本中，这个新实现被添加到使用psycopg2.extras.execute_batch()而不是executemany来初始化引擎时使用use_batch_mode=True，例如:
engine = create_engine(
"postgresql+psycopg2://scott:tiger@host/dbname",
use_batch_mode=True)
http://docs.sqlalchemy.org/en/latest/changelog/migration_12.html#change-4109
然后有人将不得不使用SQLalchmey不会费心尝试sqla和psycopg2和直接SQL的不同组合在一起。
使用aiopg -下面的代码段工作得非常好
# items = [10, 11, 12, 13]
# group = 1
tup = [(gid, pid) for pid in items]
args_str = ",".join([str(s) for s in tup])
# insert into group values (1, 10), (1, 11), (1, 12), (1, 13)
yield from cur.execute("INSERT INTO group VALUES " + args_str)
