python - 使用python将行插入Postgresql

Question

我使用 python 在 postgreqsl 中创建了一个表，并想用包含不同数据类型的随机数据集填充它。但我收到错误“并非所有参数在字符串格式化期间都已转换”。任何人都知道我做错了什么。我已阅读其他帖子，但找不到解决方案。

创建表

def create_tables():
""" create table in the PostgreSQL database"""
commands = (
    """
    Create TABLE flight_observations(
            time TIMESTAMP,
            numDayofweek INTEGER,
            numHour INTEGER,
            ac_type TEXT,
            adep TEXT,
            ades TEXT,
            curr_sect TEXT,
            lon_t FLOAT(6),
            lat_t FLOAT(6),
            vg_t INTEGER,
            hdot_t FLOAT8,
            bearing FLOAT8,
            WCA FLOAT8,
            ws FLOAT8,
            wd FLOAT8,
            temp INTEGER
    )
    """)
conn = None
try:
    # connection string
    conn_string = "host='localhost' dbname='postgres' user='postgres' password='xxxx'"
    # print connection string to connect
    print "Connecting to database\n ->%s" % (conn_string)
    # read the connection parameters
    params = Config()
    # connect to the PostgreSQL server
    conn = psycopg2.connect(conn_string)
    cur = conn.cursor()
    # create table one by one

    cur.execute(commands)
    # close communication with the PostgreSQL database server
    cur.close()
    # commit the changes
    conn.commit()
except (Exception, psycopg2.DatabaseError) as error:
    print(error)
finally:
    if conn is not None:
        conn.close()

数据

flight_obs = ['2016-07-01 16:42:21', 'A319', 'EDDB', 'EGKK', 'EDYYSOLX', 11.071111, 52.366389, 206.5938752827827, 5.55, 268.9576458923286, 5.238123301016344, 29.257257205897805, 234.0554644610864, 221.8523282183259]

填表

def insert_flight_list(flight_obs):
sql = "INSERT INTO flight_observations(time, ac_type, adep, ades, curr_sect, lon_t, lat_t, vg_t, hdot_t, bearing, wca, ws, wd, temp) VALUES ( %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)"
conn = None
try:
    # connection string
    conn_string = "host='localhost' dbname='postgres' user='postgres' password='xxxx'"
    # print connection string to connect
    print "Connecting to database\n ->%s" % (conn_string)
    # read database configuration
    params = Config()
    # connect to the PostgreSQL database
    conn = psycopg2.connect(conn_string)
    # create a new cursor
    cur = conn.cursor()
    # execute the INSERT statement
    cur.executemany(sql, flight_obs)
    conn.commit()
    cur.close()
except (Exception, psycopg2.DatabaseError) as error:
    print(error)
finally:
    if conn is not None:
        conn.close()

insert_flight_list(flight_obs)

不确定为什么这篇文章中的 try 语句没有缩进。它们在 python 代码中缩进

Answer 1

我认为问题出在 cur.executemany(sql, flight_obs) 上。文档说:

executemany(sql, vars_list)

Execute a database operation (query or command) against all parameter tuples or mappings found in the sequence vars_list.

所以它实际上相当于:

for i in flight_obs:
    cur.execute(sql, i)

因为 flight_obs 是一个字符串列表，而不是元组/映射，所以您最终会得到如下内容:

cur.execute(sql, '2016-07-01 16:42:21')
cur.execute(sql, 'A319')
cur.execute(sql, 'EDDB')

简单的修复 - 只需将 cur.executemany 替换为 cur.execute 就可以了。