Foren ikke tildelingen af @col med dine andre forespørgsler.
Få én forespørgsel for at tildele en værdi til @col, og en separat forespørgsel for at inkludere denne post i dine resultater.
SELECT @col := col AS col -- Fetch particular record given a value of
FROM tbl -- "col", assigning the identifier to @col.
WHERE col = 'd'
SELECT col -- Now include the above record in the
FROM tbl -- Final result-set
WHERE col = @col
UNION ALL
SELECT col -- Fetch the immediately preceding record,
FROM ( SELECT col -- ordered by "col"
FROM tbl
WHERE col < @col
ORDER BY col DESC
LIMIT 1) preceding
UNION ALL
SELECT col -- Fetch the immediately following record,
FROM ( SELECT col -- ordered by "col"
FROM tbl
WHERE col > @col
ORDER BY col ASC
LIMIT 1) following
ORDER BY col ASC;