One of my colleague was facing an issue while inserting 2000 values to a table variable as below:

 DECLARE @EMPLOYEEDETAILS TABLE
(OLDEMPLOYEECODE NVARCHAR(30), NEWEMPLOYEECODE NVARCHAR(30))

INSERT INTO @EMPLOYEEDETAILS(OLDEMPLOYEECODE, NEWEMPLOYEECODE)
VALUES
('93466','0000007'),
('93467','0000010'),
...
...(2000 Records)
...
('93467','00002000')

Error Message:
Msg 10738, Level 15, State 1, Line 1006
The number of row value expressions in the INSERT statement exceeds the maximum allowed number of 1000 row values.

This is a self explanatory error message as SQL Server does not support row value expressions for more than 1000 values.
To overcome the issue, the code has been modified as below and the query has been executed successfully.

Solution:

DECLARE @EMPLOYEEDETAILS TABLE
(OLDEMPLOYEECODE NVARCHAR(30), NEWEMPLOYEECODE NVARCHAR(30))

INSERT INTO @EMPLOYEEDETAILS(OLDEMPLOYEECODE, NEWEMPLOYEECODE)
SELECT * FROM (VALUES
('93466','0000007'),
('93467','0000010'),
...
...(2000 Records)
...
('93467','00002000')
) A(Col1, Col2)

You may share any other alternatives/thoughts….