sp_executesql ERROR: Procedure expects parameter '@parameters' of type 'ntext/nchar/nvarchar'

Error:

EXEC sp_executesql N'SELECT @x', '@x int', @x = 2

--or:

EXEC sp_executesql 'SELECT @x', N'@x int', @x = 2

This error message will be displayed:

Msg 214, Level 16, State 3, Procedure sp_executesql, Line 1

Procedure expects parameter '@parameters' of type 'ntext/nchar/nvarchar'.

Explanation:

The first and the second parameters of sp_executesql are Unicode - nvarchar/ntext (depend on the MSSQL version).

varchar is not valid!

Solutions:

--1.

EXEC sp_executesql N'SELECT @x', N'@x int', @x = 2

-- 2.

DECLARE @stmt nvarchar(max), @params nvarchar(max)

SET @stmt = 'SELECT @x' -- @stmt was declared as nvarchar, so the N is not required

SET @params = '@x int' -- @params was declared as nvarchar, so the N is not required

EXEC sp_executesql @stmt, @params, 2