BEGIN TRAN

CREATE TABLE A (

id int IDENTITY(1,1) PRIMARY KEY,

info nvarchar(100)

)

CREATE TABLE B (

id int IDENTITY(1,1) PRIMARY KEY,

info nvarchar(100)

)

CREATE TABLE C (

id int IDENTITY(1,1) PRIMARY KEY,

info nvarchar(100)

)

CREATE TABLE D (

id int IDENTITY(1,1) PRIMARY KEY,

info nvarchar(100)

)

CREATE TABLE E (

id int IDENTITY(1,1) PRIMARY KEY,

tabela nvarchar(100),

pk_in_tabela int

)

INSERT INTO A(info)

VALUES ('A1'), ('A2')

INSERT INTO B(info)

VALUES ('B1'), ('B2')

INSERT INTO C(info)

VALUES ('C1'), ('C2')

INSERT INTO D(info)

VALUES ('D1'), ('D2')

INSERT INTO E(tabela, pk_in_tabela)

VALUES ('A',1), ('B', 1), ('C', 2), ('D', 2)

DECLARE @i int, @CountOfE int

SELECT @i = 1,

@CountOfE = MAX(id)

FROM E

WHILE @i<= @CountOfE BEGIN

SELECT E.*, COALESCE(A.info, b.info, c.info, d.info) AS TableInfo

FROM E

LEFT JOIN A ON E.pk_in_tabela = A.id AND E.tabela = 'A'

LEFT JOIN B ON E.pk_in_tabela = B.id AND E.tabela = 'B'

LEFT JOIN C ON E.pk_in_tabela = C.id AND E.tabela = 'C'

LEFT JOIN D ON E.pk_in_tabela = D.id AND E.tabela = 'D'

WHERE e.id = @i

SET @i = @i + 1

END