Question

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String literals and escape characters in postgresql

这是我的错误：

ERROR:  type "e" does not exist

这是我的问题：

SELECT *
FROM dblink('host=theHostName port=1234 dbname=theDBName user=theUser password=thePassword',
    E'SELECT field_1, 
    CASE WHEN field_2 IS NOT NULL 
    THEN \'inactive\' ELSE \'active\' 
    END AS field_status 
    FROM the_table 
     ') 
AS linkresults(field_1 varchar(20),field_2 varchar(8))

如果我使用双引号，请删除单引号的反斜杠转义符，并在SELECT语句之前删除E

SELECT *
FROM dblink('host=theHostName port=1234 dbname=theDBName user=theUser password=thePassword',
    "SELECT field_1, 
    CASE WHEN field_2 IS NOT NULL 
    THEN 'inactive' ELSE 'active' 
    END AS field_status 
    FROM the_table 
     ") 
AS linkresults(field_1 varchar(20),field_2 varchar(8))

我明白了：

NOTICE:  identifier "SELECT ..." will be truncated

我的查询被截断后，我也得到了ERROR。

之前我已经使用这样的dblink进行了转义，所以是否有服务器设置或我需要配置的东西？

我知道如果我在sql server本身上运行它，那么查询就可以正常工作，但不能用dblink运行。有什么想法吗？

Postgres版本8.4

Answer 1

尝试用\'inactive\'替换''inactive'' - 注意：两个单引号

   SELECT *
    FROM dblink('host=theHostName port=1234 dbname=theDBName user=theUser password=thePassword',
        'SELECT field_1, 
        CASE WHEN field_2 IS NOT NULL 
        THEN ''inactive'' ELSE ''active'' 
        END AS field_status 
        FROM the_table 
         ') 

AS linkresults(field_1 varchar(20),field_2 varchar(8))

替代（上一个）解决方案

   SELECT *
    FROM dblink('host=theHostName port=1234 dbname=theDBName user=theUser password=thePassword',
        'SELECT field_1, 
        CASE WHEN field_2 IS NOT NULL 
        THEN E\'inactive\' ELSE E\'active\' 
        END AS field_status 
        FROM the_table 
         ') 

AS linkresults(field_1 varchar(20),field_2 varchar(8))

Answer 2

尝试此查询：

SELECT *
 FROM dblink('host=theHostName port=1234 dbname=theDBName user=theUser password=thePassword',
 'SELECT field_1, 
 CASE WHEN field_2 IS NOT NULL 
 THEN $$inactive$$ ELSE $$active$$ 
 END AS field_status 
 FROM the_table') 
 AS linkresults(field_1 varchar(20),field_2 varchar(8))

postgres dblink转单引号

2 个答案: