LIKE should give true for two 0-length strings. See SQL 2003 Ch. 8.5
General Rules 3)c)i)
The query SELECT * FROM t WHERE v like ''
appears to give me all rows where v is an empty
string, as expected.
But a prepared statement
SELECT * FROM t WHERE v like ?, with setString(1, "")
always returns an empty result set. See attached repro for the full example.