Using variable in SQL LIKE statement

I've got a sproc (MSSQL 2k5) that will take a variable for a LIKE claus like so:

DECLARE @SearchLetter2 char(1)
SET @SearchLetter = 't'
SET @SearchLetter2 = @SearchLetter + '%'
SELECT *
    FROM BrandNames 
    WHERE [Name] LIKE @SearchLetter2 and IsVisible = 1 
    --WHERE [Name] LIKE 't%' and IsVisible = 1 
    ORDER BY [Name]

Unfortunately, the line currently running throws a syntax error, while the commented where clause runs just fine. Can anyone help me get the un-commented line working?

If you are using a Stored Procedure:

ALTER PROCEDURE <Name>
(
	@PartialName VARCHAR(50) = NULL
)

SELECT Name 
    FROM <table>
    WHERE Name LIKE '%' + @PartialName + '%'

Joel is it that @SearchLetter hasn't been declared yet? Also the length of @SearchLetter2 isn't long enough for 't%'. Try a varchar of a longer length.

As Andrew Brower says, but adding a trim

ALTER PROCEDURE <Name>
(
    @PartialName VARCHAR(50) = NULL
)

SELECT Name 
    FROM <table>
    WHERE Name LIKE '%' + LTRIM(RTRIM(@PartialName)) + '%'

But in my opinion one important thing.

The "char(number)" it's lenght of variable.

If we've got table with "Names" like for example [Test1..Test200] and we declare char(5) in SELECT like:

DECLARE @variable char(5)
SET @variable = 'Test1%'
SELECT * FROM table WHERE Name like @variable

the result will be only - "Test1"! (char(5) - 5 chars in lenght; Test11 is 6 )

The rest of potential interested data like [Test11..Test200] will not be returned in the result.

It's ok if we want to limit the SELECT by this way. But if it's not intentional way of doing it could return incorrect results from planned ( Like "all Names begining with Test1..." ).

In my opinion if we don't know the precise lenght of a SELECTed value, a better solution could be something like this one:

DECLARE @variable varchar(max)
SET @variable = 'Test1%'
SELECT * FROM <table> WHERE variable1 like @variable

This returns (Test1 but also Test11..Test19 and Test100..Test199).

This works for me on the Northwind sample DB, note that SearchLetter has 2 characters to it and SearchLetter also has to be declared for this to run:

declare @SearchLetter2 char(2)
declare @SearchLetter char(1)
Set @SearchLetter = 'A'
Set @SearchLetter2 = @SearchLetter+'%'
select * from Customers where ContactName like @SearchLetter2 and Region='WY'

DECLARE @SearchLetter2 char(1)

Set this to a longer char.

We can write directly too...

DECLARE @SearchLetter CHAR(1) 

SET @SearchLetter = 'A' 

SELECT * 
FROM   CUSTOMERS 
WHERE  CONTACTNAME LIKE @SearchLetter + '%' 
       AND REGION = 'WY' 

or the following way as well if we have to append all the search characters then,

DECLARE @SearchLetter CHAR(1) 

SET @SearchLetter = 'A' + '%' 

SELECT * 
FROM   CUSTOMERS 
WHERE  CONTACTNAME LIKE @SearchLetter 
       AND REGION = 'WY' 

Both these will work

I had also problem using local variables in LIKE.
Important is to know: how long is variable.
Below, ORDER_NO is 50 characters long, so You can not use: LIKE @ORDER_NO, because in the end will be spaces.
You need to trim right side of the variable first.
Like this:

DECLARE @ORDER_NO char(50)
SELECT @ORDER_NO = 'OR/201910/0012%'

SELECT * FROM orders WHERE ord_no LIKE RTRIM(@ORDER_NO)

It may be as simple as LIKE '%%[%3]%%' being [%3] the input variable.

This works for me with SAP B1 9.1