Константин Цветков

Но в таблице users нет поля Phone, оно в таблице contact_info

SELECT * FROM contact_info 
  INNER JOIN contact_info AS UserPhone ON contact_info.user_id = UserPhone.user_id
  WHERE UserPhone.Phone  = '1234567'

SELECT users.*, contact_info.* FROM contact_info 
  INNER JOIN contact_info AS UserPhone ON contact_info.user_id = UserPhone.user_id
  INNER JOIN users ON users.user_id = UserPhone.user_id
  WHERE UserPhone.Phone  = '1234567'

===========================
User_id | InfoType | Value |
---------------------------
1 | 'Email' | 'q@c.com' |
1 | 'Phone' | '1234567' |
===========================

SELECT users.*, contact_info.* FROM contact_info 
  INNER JOIN contact_info AS UserPhone ON contact_info.user_id = UserPhone.user_id
  INNER JOIN users ON users.user_id = UserPhone.user_id
  WHERE UserPhone.InfoType = 'Phone' AND UserPhone.Phone  = '1234567'

SELECT reg_num, MAX( date_creation ) FROM YourTable GROUP BY reg_num

id этого объекта получить?

SELECT id, YourTable.reg_num, YourTable.date_creation 
  FROM YourTable INNER JOIN
    ( SELECT reg_num, MAX( date_creation ) AS MaxDate FROM YourTable GROUP BY reg_num ) AS M
      ON M.reg_num = YourTable.reg_num AND M.MaxDate = YourTable.date_creation

Да мне 60 для винды хватало

ссд не прожил и 5 лет

dic_value VARCHAR(MAX)

CREATE TABLE [dbo].[Dic](
	[ID] [int] IDENTITY(1,1) NOT NULL,
	[Value] [varchar](max) NOT NULL,
	[ValueUnique]  AS (hashbytes('MD5',[Value])),
 CONSTRAINT [PK_Dic] PRIMARY KEY CLUSTERED 
(
	[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, 
ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

CREATE UNIQUE NONCLUSTERED INDEX [IX_Dic] ON [dbo].[Dic]
(
	[ValueUnique] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF,
DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

ALERT (`a)
The alert (`a) character sends a beep signal to the computer's speaker.
You can use this to warn a user about an impending action.