using like vs = in exact match

[migurus]

I came across a situation where application builds a list of names by matching first three letters entered by user. The list of names does not have any duplicates The query generated by app is
SELECT LAST_NAME
FROM NAME_LIST
WHERE LAST_NAME LIKE 'GRE%'

The result set is coming back as
GREAGORS
GREEN
GREISS

Now user selects one line and application should retrieve that line, The app generate the same query as in the 3 letter case above
SELECT LAST_NAME
FROM NAME_LIST
WHERE LAST_NAME LIKE 'GREEN%'

I don't like the lazy programming, it should have been WHERE LAST_NAME = 'GREEN' in my view, my guts feeling is that the access plan for LIKE clause might be inefficient comparing to the = clause.
The example above is simplified. But in essence is LIKE less likely to produce a perfect plan comparing to =, or there is no justification to my rant.

[Erland Sommarskog]

I would execpt there is no difference of practical importance, although
may some measurable difference if you 200 processes all sending this LIKE
query.

But apart from that, I agree with you. If nothing else, assume that there
also is a GREENE in the list.



--
Erland Sommarskog, SQL Server MVP, esq...@sommarskog.se

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