Med ett index på name
, bör följande vara extremt prestanda:
SELECT DISTINCT name
FROM myTable
WHERE name LIKE CASE
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'S%') THEN '%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'St%') THEN 'S%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'Sta%') THEN 'St%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'Stac%') THEN 'Sta%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'Stack%') THEN 'Stac%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackO%') THEN 'Stack%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOv%') THEN 'StackO%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOve%') THEN 'StackOv%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOver%') THEN 'StackOve%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOverf%') THEN 'StackOver%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOverfl%') THEN 'StackOverf%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOverflo%') THEN 'StackOverfl%'
WHEN NOT EXISTS(SELECT * FROM myTable WHERE name LIKE 'StackOverflow%') THEN 'StackOverflo%'
ELSE 'StackOverflow%'
END
Se den på sqlfiddle .