更新在python中使用變量的cassandra查詢

我正在嘗試運行帶有變量的更新查詢。我正在使用casandra-driver在datastax網站中引導。我正在使用以下腳本來連接羣集並更新表ct_table中的值。更新在python中使用變量的cassandra查詢

from cassandra.cluster import Cluster 
cluster = Cluster() 
session = cluster.connect('ct_keyspace') 
a=90 
session.execute("update ct_table set value=%d where attribute='CT'",(int(a))) 
result = session.execute("select * from ct_table where attribute='CT'")[0] 
print result.attribute, result.value

我收到以下錯誤

Traceback (most recent call last): 
    File "connection.py", line 7, in <module> 
    session.execute("update ct_table set value=%d where attribute='CT'",(a)) 
    File "/usr/local/lib/python2.7/dist-packages/cassandra/cluster.py", line 1998, in execute 
    return self.execute_async(query, parameters, trace, custom_payload, timeout, execution_profile, paging_state).result() 
    File "/usr/local/lib/python2.7/dist-packages/cassandra/cluster.py", line 2035, in execute_async 
    future = self._create_response_future(query, parameters, trace, custom_payload, timeout, execution_profile, paging_state) 
    File "/usr/local/lib/python2.7/dist-packages/cassandra/cluster.py", line 2095, in _create_response_future 
    query_string = bind_params(query_string, parameters, self.encoder) 
    File "/usr/local/lib/python2.7/dist-packages/cassandra/query.py", line 823, in bind_params 
    return query % tuple(encoder.cql_encode_all_types(v) for v in params) 
TypeError: 'int' object is not iterable

我的表看起來像這樣：

cqlsh:ct_keyspace> describe ct_table 

CREATE TABLE ct_keyspace.ct_table (
    attribute text PRIMARY KEY, 
    value int 
) WITH bloom_filter_fp_chance = 0.01 
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}' 
    AND comment = '' 
    AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy'} 
    AND compression = {'sstable_compression': 'org.apache.cassandra.io.compress.LZ4Compressor'} 
    AND dclocal_read_repair_chance = 0.1 
    AND default_time_to_live = 0 
    AND gc_grace_seconds = 864000 
    AND max_index_interval = 2048 
    AND memtable_flush_period_in_ms = 0 
    AND min_index_interval = 128 
    AND read_repair_chance = 0.0 
    AND speculative_retry = '99.0PERCENTILE';

value在表中定義爲int。我懷疑我格式化錯誤地更新查詢的字符串。

來源

2016-11-10 Paul Schimmer

session.execute("update ct_table set value=%d where attribute='CT'",(int(a)))

應該

session.execute("update ct_table set value=%s where attribute='CT'", (a,))

我們指定綁定標記爲%s和傳遞元組參數一覽表。沒有尾隨逗號，這只是一個值。

還看到：您應使用％S對所有類型的參數https://datastax.github.io/python-driver/getting_started.html#passing-parameters-to-cql-queries

注意，不只是字符串

來源

2016-11-10 20:47:01

更新在python中使用變量的cassandra查詢

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