是否可以在cql脚本中的cql命令中使用变量？

Question

有没有办法在CQL脚本中使用CQL命令时传递变量,如:

select * from "Column Family Name" where "ColumnName"='A variable which takes different values';

欢迎任何建议.

Answer 1

不,CQL真的没有办法定义变量,运行循环,并根据这些变量更新/查询.

作为替代方案,我通常使用DataStax Python驱动程序来完成这样的简单任务/脚本.以下是Python脚本的摘录,我用了一段时间来填充CSV文件中的产品颜色.

# connect to Cassandra
auth_provider = PlainTextAuthProvider(username='username', password='currentHorseBatteryStaple')
cluster = Cluster(['127.0.0.1'], auth_provider=auth_provider)
session = cluster.connect('products')

# prepare statements
preparedUpdate = session.prepare(
    """
        UPDATE products.productsByItemID SET color=? WHERE itemid=? AND productid=?;
    """
)
# end prepare statements

counter = 0

# read csv file
dataFile = csv.DictReader(csvfilename, delimiter=',')
for csvRow in dataFile:
    itemid = csvRow['itemid']
    color = csvRow['customcolor']
    productid = csvRow['productid']

    #update product color
    session.execute(preparedUpdate,[color,itemid,productid])

    counter = counter + 1

# close Cassandra connection
session.cluster.shutdown()
session.shutdown()

print "updated %d colors" % (counter)

有关更多信息,请查看DataStax教程Apache Cassandra和Python入门.