如何在 Unload 中转义单引号

Question

    conn_string = "dbname='{}' port='{}' user='{}' password='{}' host='{}'"\
            .format(dbname,port,user,password,host_url) 

    sql="""UNLOAD ('select col1,col2 from %s.visitation_hourly_summary_us where col4= '2018-07-10' and col5= '1';') TO 's3://%s/%s/%s.csv' \
            credentials 'aws_access_key_id=%s;aws_secret_access_key=%s' \
            MANIFEST GZIP ALLOWOVERWRITE;Commit;""" \
            % (schema_name,s3_bucket_name, schema,table,aws_access_key_id,\
            aws_secret_access_key)

con = psycopg2.connect(conn_string)
cur = con.cursor()
cur.execute(sql)

我正在尝试执行上面的脚本来读取 table 然后在 S3

中创建一个文件

由于我的列是字符串，所以我无法跳过单引号，并且在

附近出现语法错误错误

此外，我已经尝试在 where 条件下给出 \，它仍然显示相同的错误。

非常感谢任何帮助。

谢谢

Answer 1

您可以将值放在双引号中。 'select col1,col2 from %s.visitation_hourly_summary_us where col4= "2018-07-10" and col5= "1";'

Answer 2

正如 Sarang 所说，只需将查询的 col4 和 col5 值中的单引号替换为双引号即可。

不过，我建议您将字符串分成更小的块，以便于阅读和维护。这样，您应该能够按照 chepner 的建议使用 execute（和 MySQL documentation）：

# Create the inner SQL statement. Notice the single quotes for the general
# string and the double quotes for the col4 and col5 values
sql_stmt = ('SELECT col1, col2 '
            'FROM %s.visitation_hourly_summary_us '
            'WHERE col4 = "2018-07-10" AND col5= "1";' % schema_name)

# Format the s3 path
s3_target = 's3://%s/%s/%s.csv' % (s3_bucket_name, schema, table)

# Format credentials string
s3_credentials = 'aws_access_key_id=%s;aws_secret_access_key=%s' % (
    aws_access_key_id, aws_secret_access_key)

# Create a tuple with all preformatted strings
data = (sql_stmt, s3_target, s3_credentials)

# Format the s3 query skeleton
s3_stmt = ("UNLOAD ('%s') TO '%s' "
           "CREDENTIALS '%s' "
           "MANIFEST GZIP ALLOWOVERWRITE;Commit;")

con = psycopg2.connect(conn_string)
cur = con.cursor()
cur.execute(s3_stmt, data)

Answer 3

'（单引号可以发送为）-> \\\\'

我在 R 和 python 中都用过这个请寻找解决方案

如果您的 sql QUERY 是

Select * 来自 sample_table 其中 register_date='2018-12-31'

然后卸载命令这样写

sql=     """unload ('Select * from tnltemp.otpsuccess_details where register_date=\\'2018-12-31\\' ')
        to 's3://my-bucket/migration/exported_sample_table_' credentials 
        'aws_access_key_id=12234123;aws_secret_access_key=12345'
        DELIMITER AS ','
        NULL AS ''
        parallel off;""""



cur = con.cursor()
cur.execute(sql)

Answer 4

您可能希望使用两个单引号将值括起来。

If your query contains quotes (for example to enclose literal values), put the literal between two sets of single quotation marks—you must also enclose the query between single quotation marks:

示例：

UNLOAD ('select * from venue where venuestate=''NV''')

摘自红移文档： https://docs.aws.amazon.com/redshift/latest/dg/r_UNLOAD.html

Answer 5

你也可以使用 postgres 风格:

unload 
($$
select * from table where id='ABC'
$$)
to 's3://bucket/queries_results/20150324/table_dump/'
credentials 'aws_access_key_id=;aws_secret_access_key='
;

如何在 Unload 中转义单引号

How to escape single quotes in Unload

python

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