需要SQL语法

我在sql中得到了3个表，如下所示：需要sql语法

一,

二,

三,

我想得到： xy8vx_users.username和xy8vx_users.email，满足条件

submission_values.FieldName = 'data2' AND submission_values.FieldValue = '10.03.2012'

我已经花了两个小时，谁也帮不了我

我试过这样做：但不起作用

SELECT sub.Username
FROM `xy8vx_rsform_submission_values` AS value
JOIN `xy8vx_rsform_submissions` AS sub ON value.SubmissionId = sub.SubmissionId
JOIN xy8vx_users ` AS users ON sub.Username = users.email WHERE value.FieldName = 'data2' AND value.FieldValue = '10.03.2012'`

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如果你想让任何人能够帮助你，你应该考虑发布你的数据库模式。试着花些时间读一本书或一个SQL教程。此外，字符串但不工作不是任何RDBMS中的内置错误消息。

.xy8vx_rsform_submissions_values
-SubmissionId
-FieldName
-FieldValue
-...

submission_values.FieldName = 'data2' AND submission_values.FieldValue = '10.03.2012'

SELECT sub.Username
FROM `xy8vx_rsform_submission_values` AS value
JOIN `xy8vx_rsform_submissions` AS sub ON value.SubmissionId = sub.SubmissionId
JOIN xy8vx_users ` AS users ON sub.Username = users.email WHERE value.FieldName = 'data2' AND value.FieldValue = '10.03.2012'`

select xy8vx_users.username, xy8vx_users,email
from
submission_values 
inner join
submissions on 
submission_values.SubmissionId = submissions.SubmissionId
inner join
xy8vx_users on
submissions.Username = xy8vx_users.username
where 
submission_values.FieldName = 'data2'
and 
submission_values.FieldValue = '10.03.2012'