MSSQL: validates_uniqueness_of causes invalid SQL to be generated about activerecord-jdbc-adapter

[sshamilton]

I had the same problem when moving to 3.0.7, however even after turning off uniqueness for the column, the problem persisted.

[nicksieger]

Sure enough, we have a failing test already for it:

  1) Error:
test_validates_uniqueness_of_strings_case_insensitive(MsSQLSimpleTest):
ActiveRecord::StatementInvalid: ActiveRecord::JDBCError: No column name was specified for column 2 of 't'.: SELECT t.* FROM (SELECT ROW_NUMBER() OVER(ORDER BY [validates_uniqueness_of].id) AS _row_num, 1 FROM [validates_uniqueness_of] WHERE ([validates_uniqueness_of].[cs_string] = N'1')) AS t WHERE t._row_num BETWEEN 1 AND 1

[arkadiyk]

after some investigation I found out that this problem caused by new logic in AR .exists? method. I created an issue with Rails : rails/rails#1623