SQL Server 2016

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CREATE TABLE t(id INT, a NVARCHAR(10), RowNumber INT);

INSERT INTO t(id, a)
VALUES (10, 'a'),(11,'b'),(13,'c');
3 rows affected

CREATE TABLE t2(id INT, b NVARCHAR(10), RowNumber INT);

INSERT INTO t2(id, b)
VALUES (100, 'x'),(101,'y'),(103,'z');
3 rows affected

DECLARE @TableName SYSNAME = 't';

DECLARE @i AS INT = 0 ;
DECLARE @SQLString NVARCHAR(MAX);
DECLARE @ParmDefinition NVARCHAR(MAX);



SET @SQLString = N'WITH cte AS (SELECT *, rn = ROW_NUMBER() OVER(ORDER BY (SELECT 1)) FROM <TableName>)UPDATE cte SET RowNumber = @i + rn';
SET @ParmDefinition = N'@i  TINYINT';

SET @SQLString = REPLACE(@SQLString, '<TableName>', QUOTENAME(@TableName));

PRINT @SQLString;  -- debug

EXECUTE sp_executesql @SQLString, @ParmDefinition, @i = @i;
WITH cte AS (SELECT *, rn = ROW_NUMBER() OVER(ORDER BY (SELECT 1)) FROM [t])UPDATE cte SET RowNumber = @i + rn
3 rows affected

SELECT * FROM t;


id
a
RowNumber


10
a
1

11
b
2

13
c
3


DECLARE @TableName SYSNAME = 't2';

DECLARE @i AS INT = 10 ;
DECLARE @SQLString NVARCHAR(MAX);
DECLARE @ParmDefinition NVARCHAR(MAX);



SET @SQLString = N'WITH cte AS (SELECT *, rn = ROW_NUMBER() OVER(ORDER BY (SELECT 1)) FROM <TableName>)UPDATE cte SET RowNumber = @i + rn';
SET @ParmDefinition = N'@i  TINYINT';

SET @SQLString = REPLACE(@SQLString, '<TableName>', QUOTENAME(@TableName));

PRINT @SQLString;  -- debug

EXECUTE sp_executesql @SQLString, @ParmDefinition, @i = @i;
WITH cte AS (SELECT *, rn = ROW_NUMBER() OVER(ORDER BY (SELECT 1)) FROM [t2])UPDATE cte SET RowNumber = @i + rn
3 rows affected

SELECT * FROM t2;


id
b
RowNumber


100
x
11

101
y
12

103
z
13