Delete the 'first' record from a table in SQL Server, without a WHERE condition

WITH  q AS
        (
        SELECT TOP 1 *
        FROM    mytable
        /* You may want to add ORDER BY here */
        )
DELETE
FROM    q

Note that

DELETE TOP (1)
FROM   mytable

will also work, but, as stated in the documentation:

The rows referenced in the TOP expression used with INSERT, UPDATE, or DELETE are not arranged in any order.

Therefore, it's better to use WITH and an ORDER BY clause, which will let you specify more exactly which row you consider to be the first.

depends on your DBMS

-- MYSql:
DELETE FROM table LIMIT 1;
-- Postgres:
DELETE FROM table LIMIT 1;
-- MSSql:
DELETE TOP(1) FROM table;
-- Oracle:
DELETE FROM table WHERE ROWNUM = 1;

No, AFAIK, it's not possible to do it portably.

There's no defined "first" record anyway - on different SQL engines it's perfectly possible that "SELECT * FROM table" might return the results in a different order each time.

Define "First"? If the table has a PK then it will be ordered by that, and you can delete by that:

DECLARE @TABLE TABLE
(
    ID INT IDENTITY(1,1) NOT NULL PRIMARY KEY,
    Data NVARCHAR(50) NOT NULL
)

INSERT INTO @TABLE(Data)
SELECT 'Hello' UNION
SELECT 'World' 

SET ROWCOUNT 1
DELETE FROM @TABLE
SET ROWCOUNT 0

SELECT * FROM @TABLE

If the table has no PK, then ordering won't be guaranteed...

Does this really make sense?
There is no "first" record in a relational database, you can only delete one random record.

What do you mean by «'first' record from a table» ? There's no such concept as "first record" in a relational db, i think.

Using MS SQL Server 2005, if you intend to delete the "top record" (the first one that is presented when you do a simple "*select * from tablename*"), you may use "delete top(1) from tablename"... but be aware that this does not assure which row is deleted from the recordset, as it just removes the first row that would be presented if you run the command "select top(1) from tablename".