Q:

Taking input of Column name to a Variable and Updating the input Column Values using Cursor

Trying to take input of Table name and Column name from a Table(Having column Names which Tables and Columns to Modify)  and modifying the Column values of the Table(input received from which table to modify) 
DECLARE @TABLE_1 NVARCHAR(MAX)--Passing Table name  to Modify
DECLARE @COLUMN_NAME NVARCHAR(300)--Passing Column name to modify
DECLARE INPUT_CURSOR CURSOR FOR 
/*Actual Table contains which Table and Column to modify*/
SELECT TABLE_NAME,COLUMN_NAME FROM INPUT
OPEN INPUT_CURSOR
FETCH NEXT FROM INPUT_CURSOR INTO @TABLE_1, @COLUMN_NAME
WHILE @@FETCH_STATUS=0
BEGIN
SET @TABLE_1='TABLE_NAME'-- INPUT TABLE_NAME
SET @COLUMN_NAME='COLUMN_NAME'--INPUT COLUMN_NAME
DECLARE @EXEC_SQL NVARCHAR(MAX)--To execute Dynamic SQL Update Statement
SET @EXEC_SQL= 'UPDATE'+'  ['+@TABLE_1+'] '+'SET'+'
'+@COLUMN_NAME+'=REVERSE( (999999999-'+@COLUMN_NAME+'))'
EXEC(@EXEC_SQL)
FETCH NEXT FROM INPUT_CURSOR INTO @TABLE_1,@COLUMN_NAME
END
CLOSE INPUT_CURSOR
DEALLOCATE INPUT_CURSOR

Receiving Error
Msg 208, Level 16, State 1, Line 1
Invalid object name 'TABLE_NAME'.
Msg 208, Level 16, State 1, Line 1
Invalid object name 'TABLE_NAME'.
Msg 208, Level 16, State 1, Line 1
Invalid object name 'TABLE_NAME'.
Msg 208, Level 16, State 1, Line 1
Invalid object name 'TABLE_NAME'.

A:

DECLARE INPUT_CURSOR CURSOR FOR 

/*Actual Table contains which Table and Column to modify*/
SELECT TABLE_NAME, COLUMN_NAME FROM INPUT 

/*Cursor invokes each table and column name to be modified Passed to
@Table_1,@Column_Name*/
OPEN INPUT_CURSOR
DECLARE @TABLE_1 NVARCHAR(300)--Passing Table name  to Modify
DECLARE @COLUMN_NAME NVARCHAR(300)--Passing Column name to modify
FETCH NEXT FROM INPUT_CURSOR INTO @TABLE_1, @COLUMN_NAME
WHILE @@FETCH_STATUS=0
BEGIN
DECLARE @EXEC_SQL NVARCHAR(MAX)--To execute Dynamic SQL Update Statement
SET @EXEC_SQL= 'UPDATE'+'  ['+@TABLE_1+'] '+'SET'+'  '+@COLUMN_NAME+ 
'=REVERSE( (999999999-'+@COLUMN_NAME+'))'
EXEC(@EXEC_SQL)
FETCH NEXT FROM INPUT_CURSOR INTO @TABLE_1,@COLUMN_NAME
END
CLOSE INPUT_CURSOR
DEALLOCATE INPUT_CURSOR

