Question

我一直在收到错误代码：1060。：

重复列名称'NULL'
重复列名'2016-08-04 01:25:06'
重复列名称'john'

但是，我需要插入一些具有相同值的字段，但SQL拒绝并显示上述错误。错误可能是sql无法选择相同的列名，在这种情况下是否有其他编写代码的方法？以下是我目前的代码

INSERT INTO test.testTable SELECT * 
FROM (SELECT NULL, 'hello', 'john', '2016-08-04 01:25:06', 'john'
, '2016-08-04 01:25:06', NULL, NULL) AS tmp
WHERE NOT EXISTS (SELECT * FROM test.testTable WHERE message= 'hello' AND created_by = 'john') LIMIT 1

我的专栏：

（id，message，created_by，created_date，updated_by，updated_date，deleted_by，deleted_date）

请帮助，谢谢。

Answer 1

您的重复列名称来自您的子查询。您多次选择null，john和2016-08-04 01:25:06。使用名称/别名提供您选择的列：

INSERT INTO test.testTable 
SELECT * 
FROM (SELECT NULL as col1, 'hello' as col2, 
       'john' as col3, '2016-08-04 01:25:06' as col4, 
       'john' as col5, '2016-08-04 01:25:06' as col6, 
       NULL as col7, NULL as col8) AS tmp
WHERE NOT EXISTS (SELECT * 
                  FROM test.testTable 
                  WHERE message= 'hello' AND created_by = 'john')
LIMIT 1

此处不确定limit 1是否有用，您只选择可能插入的单行。

Answer 2

您正在使用子查询。因为你没有给列别名，MySQL必须为你选择别名 - 它选择用于定义的公式。

您可以在没有子查询的情况下编写查询：

INSERT INTO test.testTable( . . .)
    SELECT NULL, 'hello', 'john', '2016-08-04 01:25:06', 'john',
           '2016-08-04 01:25:06', NULL, NULL
    FROM dual
    WHERE NOT EXISTS (SELECT 1
                      FROM test.testTable tt
                      WHERE tt.message = 'hello' AND tt.created_by = 'john'
                     );

如果您在SELECT中使用子查询，则在WHERE子查询中使用相关子句：

INSERT INTO test.testTable( . . .)
    SELECT * 
    FROM (SELECT NULL as col1, 'hello' as message, 'john' as created_by,
                 '2016-08-04 01:25:06' as date, 'john' as col2,
                 '2016-08-04 01:25:06' as col3, NULL as col4, NULL as col5
         ) t
    WHERE NOT EXISTS (SELECT 1
                      FROM test.testTable tt
                      WHERE tt.message = t.message AND
                            tt.created_by = t.created_by
                     );

此外，LIMIT 1没有做任何事情，因为你只有一行。

错误代码：1060。列名重复

2 个答案: