StackOverflow question #42109425, Sql Server

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DECLARE @Table1 as table (
      [ID] [bigint]
    , [RecTime] [datetime]
)
DECLARE @Table2 as table (
      [ID] [bigint]
    , [RecTime] [datetime]
)
DECLARE @Table3 as table (
      [ID] [bigint]
    , [RecTime] [datetime]
)

DECLARE @Files as table (
      [ID] [bigint]
    , [tblName] nvarchar(255) NULL
    , [tblID] bigint NULL
    , [BinaryData]  varbinary(max)
    /* and some other columns */
)

INSERT INTO @Table1 (
      [ID]
    , [RecTime]
)
          SELECT '1', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '2', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '3', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '4', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '5', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)

INSERT INTO @Table2 (
      [ID]
    , [RecTime]
)
          SELECT '11', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '12', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '13', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '14', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '15', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)

INSERT INTO @Table3 (
      [ID]
    , [RecTime]
)
          SELECT '21', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '22', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '23', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '24', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)
UNION ALL SELECT '25', DATEADD(day, (ABS(CHECKSUM(NEWID())) % 65530), 0)

INSERT INTO @Files (
      [ID]
    , [tblName]
    , [tblID]
    , [BinaryData]
)
          SELECT '1', 'Table1', '1', 0x010203040506
UNION ALL SELECT '2', 'Table1', '2', 0x010203040506
UNION ALL SELECT '3', 'Table1', '2', 0x010203040506
UNION ALL SELECT '4', 'Table1', '3', 0x010203040506
UNION ALL SELECT '5', 'Table1', '4', 0x010203040506
UNION ALL SELECT '6', 'Table1', '5', 0x010203040506
UNION ALL SELECT '7', 'Table1', '5', 0x010203040506

UNION ALL SELECT '8', 'Table2', '1', 0x010203040506
UNION ALL SELECT '9', 'Table2', '3', 0x010203040506
UNION ALL SELECT '10', 'Table2', '3', 0x010203040506
UNION ALL SELECT '11', 'Table2', '4', 0x010203040506
UNION ALL SELECT '12', 'Table2', '5', 0x010203040506
UNION ALL SELECT '13', 'Table2', '5', 0x010203040506
UNION ALL SELECT '14', 'Table2', '5', 0x010203040506

UNION ALL SELECT '15', 'Table3', '1', 0x010203040506
UNION ALL SELECT '16', 'Table3', '1', 0x010203040506
UNION ALL SELECT '17', 'Table3', '1', 0x010203040506
UNION ALL SELECT '18', 'Table3', '3', 0x010203040506
UNION ALL SELECT '19', 'Table3', '3', 0x010203040506
UNION ALL SELECT '20', 'Table3', '3', 0x010203040506
UNION ALL SELECT '21', 'Table3', '4', 0x010203040506

SELECT * FROM @Table1
SELECT * FROM @Table2
SELECT * FROM @Table3

SELECT * FROM @Files

-- Copy table variables into temporary tables so they can be referenced from dynamic SQL
    SELECT * INTO #Table1 FROM @Table1;
    SELECT * INTO #Table2 FROM @Table2;
    SELECT * INTO #Table3 FROM @Table3;

-- Create a temporary table for storing the results
    CREATE TABLE #results (
          [ID] [bigint]
        , [tblName] nvarchar(255) NULL
        , [tblID] bigint NULL
        , [BinaryData]  varbinary(max)
        , [RecTime] [datetime]
    );

-- Declare placeholders and cursor
    DECLARE @ID bigint;
    DECLARE @tblName nvarchar(255);
    DECLARE @tblID bigint;
    DECLARE @BinaryData varbinary(max);
    DECLARE @RecTime datetime;
    DECLARE @sql nvarchar(max);
    DECLARE @params nvarchar(max);

DECLARE files_cursor CURSOR FOR  
    SELECT ID, tblName, tblID, BinaryData
    FROM @Files

-- Loop over all rows in the @Files table
    OPEN files_cursor   
    FETCH NEXT FROM files_cursor INTO @ID, @tblName, @tblID, @BinaryData

WHILE @@FETCH_STATUS = 0   
    BEGIN   
       -- Find the referenced table row and extract its RecTime.
       SET @RecTime = NULL;
       SET @sql = CONCAT(
           'SELECT @RecTime = RecTime FROM #', @tblName, ' WHERE ID = ', @tblID);
       SET @params = '@RecTime datetime out';
       
       EXEC SP_EXECUTESQL @sql, @params, @RecTime out;
       
       -- Add result
       INSERT INTO #results (ID, tblName, tblID, BinaryData, RecTime)
       VALUES (@ID, @tblName, @tblID, @BinaryData, @RecTime);

FETCH NEXT FROM files_cursor INTO @ID, @tblName, @tblID, @BinaryData;
    END

-- Finalise
    CLOSE files_cursor;
    DEALLOCATE files_cursor;

-- Display the results from temporary table
    SELECT * FROM #results;

View schema
Execution time: 0,06 sec, rows selected: 127, rows affected: 57, absolute service time: 0,23 sec