should be it

external/duckdb/test/sql/function/string/test_levenshtein.test

@@ -0,0 +1,287 @@
+# name: test/sql/function/string/test_levenshtein.test
+# description: Test levenshtein function
+# group: [string]
+
+statement ok
+PRAGMA enable_verification
+
+
+# normal queries
+query I
+SELECT levenshtein('hallo', 'hallo')
+----
+0
+
+query I
+SELECT levenshtein('hallo', 'hello')
+----
+1
+
+query I
+SELECT levenshtein('hello', 'hallo')
+----
+1
+
+query I
+SELECT levenshtein('lawn', 'flaw')
+----
+2
+
+query I
+SELECT levenshtein('flaw', 'lawn')
+----
+2
+
+query I
+SELECT levenshtein('kitten', 'sitting')
+----
+3
+
+query I
+SELECT levenshtein('sitting', 'kitten')
+----
+3
+
+query I
+SELECT levenshtein('hallo', 'hoi')
+----
+4
+
+query I
+SELECT levenshtein('hoi', 'hallo')
+----
+4
+
+query I
+SELECT levenshtein(NULL, 'hi')
+----
+NULL
+
+query I
+SELECT levenshtein('hi', NULL)
+----
+NULL
+
+query I
+SELECT levenshtein(NULL, NULL)
+----
+NULL
+
+query I
+SELECT levenshtein('', NULL)
+----
+NULL
+
+query I
+SELECT levenshtein(NULL, '')
+----
+NULL
+
+query I
+SELECT levenshtein('', 'hi')
+----
+2
+
+query I
+SELECT levenshtein('hi', '')
+----
+2
+
+query I
+SELECT levenshtein('', '')
+----
+0
+
+
+statement ok
+CREATE TABLE strings(s VARCHAR)
+
+statement ok
+INSERT INTO strings VALUES ('hello'), ('hallo'), ('aloha'), ('fello'), ('fellow'), ('ducks')
+
+query I
+SELECT levenshtein(s, 'hallo') FROM strings ORDER BY s
+----
+4
+5
+2
+3
+0
+1
+
+query I
+SELECT levenshtein('hallo', s) FROM strings ORDER BY s
+----
+4
+5
+2
+3
+0
+1
+
+query I
+SELECT levenshtein(NULL, s) FROM strings
+----
+NULL
+NULL
+NULL
+NULL
+NULL
+NULL
+
+query I
+SELECT levenshtein(NULL, s) FROM strings
+----
+NULL
+NULL
+NULL
+NULL
+NULL
+NULL
+
+query I
+SELECT levenshtein('', s) FROM strings ORDER BY s
+----
+5
+5
+5
+6
+5
+5
+
+query I
+SELECT levenshtein(s, '') FROM strings ORDER BY s
+----
+5
+5
+5
+6
+5
+5
+
+
+statement ok
+DROP TABLE strings
+
+statement ok
+CREATE TABLE strings(s VARCHAR)
+
+statement ok
+INSERT INTO strings VALUES (NULL)
+
+query I
+SELECT levenshtein(s, NULL) from strings
+----
+NULL
+
+query I
+SELECT levenshtein(NULL, s) from strings
+----
+NULL
+
+query I
+SELECT levenshtein('hi', s) from strings
+----
+NULL
+
+query I
+SELECT levenshtein(s, 'hi') from strings
+----
+NULL
+
+query I
+SELECT levenshtein('', s)  FROM strings
+----
+NULL
+
+query I
+SELECT levenshtein(s, '')  FROM strings
+----
+NULL
+
+
+statement ok
+DROP TABLE strings
+
+statement ok
+CREATE TABLE strings(s VARCHAR)
+
+statement ok
+INSERT INTO strings VALUES ('')
+
+query I
+SELECT levenshtein(NULL, s)  FROM strings
+----
+NULL
+
+query I
+SELECT levenshtein(s, NULL)  FROM strings
+----
+NULL
+
+query I
+SELECT levenshtein(s, '')  FROM strings
+----
+0
+
+query I
+SELECT levenshtein('', s)  FROM strings
+----
+0
+
+query I
+SELECT levenshtein(s, 'hi')  FROM strings
+----
+2
+
+query I
+SELECT levenshtein('hi', s)  FROM strings
+----
+2
+
+
+# editdist3
+query I
+SELECT editdist3('hallo', 'hello')
+----
+1
+
+query I
+SELECT editdist3(s, 'hello') FROM strings
+----
+5
+
+# Comparing fields from two columns row wise
+
+statement ok
+DROP TABLE strings
+
+statement ok
+CREATE TABLE strings(s VARCHAR, t VARCHAR)
+
+statement ok
+INSERT INTO strings VALUES 	('hello', 'hello'), ('hello', 'hallo'), ('flaw', 'lawn'),
+							('sitting', 'kitten'), ('hallo', 'aloha'), ('hello', 'aloha'),
+							(NULL, NULL), ('', ''),
+							(NULL, 'bora'), ('bora', NULL),
+							('hi', ''), ('', 'hi'),
+							(NULL, ''), ('', NULL)
+
+
+query I
+SELECT levenshtein(s, t) ld FROM strings
+----
+0
+1
+2
+3
+4
+5
+NULL
+0
+NULL
+NULL
+2
+2
+NULL
+NULL