using WHERE IN in t-sql

I'm using the Employees table of the sample Northwind Sql Server.

It looks like this:
p1.PNG
Here is the script to create the table:

USE [Northwind]
GO

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Employees](
	[EmployeeID] [int] NOT NULL,
	[LastName] [nvarchar](20) NOT NULL,
	[FirstName] [nvarchar](10) NOT NULL,
	[Title] [nvarchar](30) NULL,
	[TitleOfCourtesy] [nvarchar](25) NULL,
	[BirthDate] [datetime] NULL,
	[HireDate] [datetime] NULL,
	[Address] [nvarchar](60) NULL,
	[City] [nvarchar](15) NULL,
	[Region] [nvarchar](15) NULL,
	[PostalCode] [int] NULL,
	[Country] [nvarchar](15) NULL,
 CONSTRAINT [PK_Employees_Employees] PRIMARY KEY CLUSTERED 
(
	[EmployeeID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (1, N'Davolio', N'Nancy', N'Sales Representative', N'Ms.', CAST(N'1948-12-08T00:00:00.000' AS DateTime), CAST(N'1992-05-01T00:00:00.000' AS DateTime), N'507 - 20th Ave. E.
Apt. 2A', N'Seattle', N'WA', 98122, N'USA')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (2, N'Fuller', N'Andrew', N'Vice President, Sales', N'Dr.', CAST(N'1952-02-19T00:00:00.000' AS DateTime), CAST(N'1992-08-14T00:00:00.000' AS DateTime), N'908 W. Capital Way', N'Tacoma', N'WA', 98401, N'USA')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (3, N'Leverling', N'Janet', N'Sales Representative', N'Ms.', CAST(N'1963-08-30T00:00:00.000' AS DateTime), CAST(N'1992-04-01T00:00:00.000' AS DateTime), N'722 Moss Bay Blvd.', N'Kirkland', N'WA', 98033, N'USA')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (4, N'Peacock', N'Margaret', N'Sales Representative', N'Mrs.', CAST(N'1937-09-19T00:00:00.000' AS DateTime), CAST(N'1993-05-03T00:00:00.000' AS DateTime), N'4110 Old Redmond Rd.', N'Redmond', N'WA', 98052, N'USA')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (5, N'Buchanan', N'Steven', N'Sales Manager', N'Mr.', CAST(N'1955-03-04T00:00:00.000' AS DateTime), CAST(N'1993-10-17T00:00:00.000' AS DateTime), N'14 Garrett Hill', N'London', NULL, 95624, N'UK')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (6, N'Suyama', N'Michael', N'Sales Representative', N'Mr.', CAST(N'1963-07-02T00:00:00.000' AS DateTime), CAST(N'1993-10-17T00:00:00.000' AS DateTime), N'Coventry House
Miner Rd.', N'London', NULL, 93722, N'UK')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (7, N'King', N'Robert', N'Sales Representative', N'Mr.', CAST(N'1960-05-29T00:00:00.000' AS DateTime), CAST(N'1994-01-02T00:00:00.000' AS DateTime), N'Edgeham Hollow
Winchester Way', N'London', NULL, 45648, N'UK')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (8, N'Callahan', N'Laura', N'Inside Sales Coordinator', N'Ms.', CAST(N'1958-01-09T00:00:00.000' AS DateTime), CAST(N'1994-03-05T00:00:00.000' AS DateTime), N'4726 - 11th Ave. N.E.', N'Seattle', N'WA', 98105, N'USA')
GO
INSERT [dbo].[Employees] ([EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [BirthDate], [HireDate], [Address], [City], [Region], [PostalCode], [Country]) VALUES (9, N'Dodsworth', N'Anne', N'Sales Representative', N'Ms.', CAST(N'1966-01-27T00:00:00.000' AS DateTime), CAST(N'1994-11-15T00:00:00.000' AS DateTime), N'7 Houndstooth Rd.', N'London', NULL, 98751, N'UK')
GO

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I'm trying to using the WHERE IN clause to use a parameter string list.

I have the following query but it returns nothing. It should be returning the record for Davolio and King.

What am I missing in my query?

DECLARE @LastName NVARCHAR(MAX)
SET @LastName = 'Davolio,King'

SELECT [EmployeeID]
      ,[LastName]
      ,[FirstName]
      ,[Title]
      ,[TitleOfCourtesy]
  FROM [Northwind].[dbo].[Employees]
WHERE LastName IN ( @LastName)
LVL 1
maqskywalkerAsked:
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Ryan ChongBusiness Systems Analyst , ex-Senior Application EngineerCommented:
try like:

DECLARE @Output VARCHAR(4000), @XML XML
DECLARE @LastName NVARCHAR(MAX)
SET @LastName = 'Davolio,King'

Set @Output = '<list><item>' + REPLACE(@LastName, ',', '</item><item>') + '</item></list>'
Set @XML = Convert(XML, @Output)

;with cte as
(
    select ltrim(rtrim(n.c.value('.','varchar(max)'))) AS LastName
    from @XML.nodes('//item') n(c) 
)
SELECT [EmployeeID]
      ,[LastName]
      ,[FirstName]
      ,[Title]
      ,[TitleOfCourtesy]
  FROM [Northwind].[dbo].[Employees]
WHERE LastName IN ( Select LastName from cte)

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0
Nitin SontakkeDeveloperCommented:
Yet another way is to use an UDF, split and then use it in a where clause.

For example:

SELECT [EmployeeID]
      ,[LastName]
      ,[FirstName]
      ,[Title]
      ,[TitleOfCourtesy]
  FROM [Northwind].[dbo].[Employees]
WHERE LastName IN (select data from [dbo].[split](@LastName, ','))

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And the good news is, if you are using Microsoft SQL Server 2016 (or later) there is a built-in function string_split.

Hope it helps!
0

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maqskywalkerAuthor Commented:
Thanks. Good info.
0
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