Hi.

I have some questions related to the func.c file, however before that I 
would ask you to fix tests.

General ideas:

1. Those tests are regresson tests (it just tests that problem will not 
appear in the future).
     We name those tests in the following manear: 
gh-XXXX-short-description.test.lua
2. The thing you test is not related to a table and other columns.
     Please, convert the tests to the next format: {[[select '' like 
'_B';]], {1}]]}.
     To make it more readable, you can do it like `like_testcases` in 
`sql-tap/collation.test.lua`.
3. There is two extra things that should be tested:
     1. When string or pattern ends with incorrect unicode symbol (e.g. 
half of the whole unicode symbol)
     2. String or pattern contains incorrect unicode symbol.

Implementing 3 point may require some additional investigations. E.g. it 
is ok for a blob to have invalid Unicode symbols.
> diff --git a/test/sql-tap/like1.test.lua b/test/sql-tap/like1.test.lua
> new file mode 100755
> index 0000000..807ee65
> --- /dev/null
> +++ b/test/sql-tap/like1.test.lua
> @@ -0,0 +1,181 @@
> +#!/usr/bin/env tarantool
> +test = require("sqltester")
> +test:plan(16)
> +
> +test:do_catchsql_test(
> +"like-test-1.1",
> +[[
> +CREATE TABLE t2 (column1 INTEGER,
> +     column2 VARCHAR(100),
> +     column3 BLOB,
> +     column4 FLOAT,
> +     PRIMARY KEY (column1, column2));
> +INSERT INTO t2 VALUES (1, 'AB', X'4142', 5.5);
> +INSERT INTO t2 VALUES (1, 'CD', X'2020', 1E4);
> +INSERT INTO t2 VALUES (2, 'AB', X'2020', 12.34567);
> +INSERT INTO t2 VALUES (-1000, '', X'', 0.0);
> +CREATE TABLE t1 (a INT PRIMARY KEY, str VARCHAR(100));
> +INSERT INTO t1 VALUES (1, 'ab');
> +INSERT INTO t1 VALUES (2, 'abCDF');
> +INSERT INTO t1 VALUES (3, 'CDF');
> +CREATE TABLE t (s1 char(2) primary key, s2 char(2));
> +INSERT INTO t VALUES ('AB', 'AB');
> +]], {
> +-- <like-test-1.1>
> +0
> +-- <like-test-1.1>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.2",
> +[[
> +SELECT column1, column2, column1 * column4 FROM t2 WHERE column2 LIKE 
> '_B';
> +]], {
> +-- <like-test-1.2>
> +1, 'AB', 5.5, 2, 'AB', 24.69134
> +-- <like-test-1.2>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.3",
> +[[
> +SELECT column1, column2 FROM t2 WHERE column2 LIKE '%B';
> +]], {
> +             -- <like-test-1.3>
> +             1, 'AB', 2, 'AB'
> +             -- <like-test-1.3>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.4",
> +[[
> +SELECT column1, column2 FROM t2 WHERE column2 LIKE 'A__';
> +]], {
> +             -- <like-test-1.4>
> +
> +             -- <like-test-1.4>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.5",
> +[[
> +SELECT column1, column2 FROM t2 WHERE column2 LIKE 'A_';
> +]], {
> +             -- <like-test-1.5>
> +             1, 'AB', 2, 'AB'
> +             -- <like-test-1.5>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.6",
> +[[
> +SELECT column1, column2 FROM t2 WHERE column2 LIKE 'A';
> +]], {
> +             -- <like-test-1.6>
> +
> +             -- <like-test-1.6>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.7",
> +[[
> +SELECT column1, column2 FROM t2 WHERE column2 LIKE '_';
> +]], {
> +             -- <like-test-1.7>
> +
> +             -- <like-test-1.7>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.8",
> +[[
> +SELECT * FROM t WHERE s1 LIKE '%A';
> +]], {
> +             -- <like-test-1.8>
> +
> +             -- <like-test-1.8>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.9",
> +[[
> +SELECT * FROM t WHERE s1 LIKE '%C';
> +]], {
> +             -- <like-test-1.9>
> +
> +             -- <like-test-1.9>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.10",
> +[[
> +SELECT * FROM t1 WHERE str LIKE '%df';
> +]], {
> +             -- <like-test-1.10>
> +             2, 'abCDF', 3, 'CDF'
> +             -- <like-test-1.10>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.11",
> +[[
> +SELECT * FROM t1 WHERE str LIKE 'a_';
> +]], {
> +             -- <like-test-1.11>
> +             1, 'ab'
> +             -- <like-test-1.11>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.12",
> +[[
> +SELECT column1, column2 FROM t2 WHERE column2 LIKE '__';
> +]], {
> +             -- <like-test-1.12>
> +             1, 'AB', 1, 'CD', 2, 'AB'
> +             -- <like-test-1.12>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.13",
> +[[
> +SELECT str FROM t1 WHERE str LIKE 'ab%';
> +]], {
> +-- <like-test-1.13>
> +'ab', 'abCDF'
> +-- <like-test-1.13>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.14",
> +[[
> +SELECT str FROM t1 WHERE str LIKE 'abC%';
> +]], {
> +-- <like-test-1.14>
> +'abCDF'
> +-- <like-test-1.14>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.15",
> +[[
> +SELECT str FROM t1 WHERE str LIKE 'a_%';
> +]], {
> +-- <like-test-1.15>
> +'ab', 'abCDF'
> +-- <like-test-1.15>
> +})
> +
> +test:do_execsql_test(
> +"like-test-1.16",
> +[[
> +DROP TABLE t1;
> +DROP TABLE t2;
> +DROP TABLE t;
> +]], {
> +             -- <like-test-1.16>
> +
> +             -- <like-test-1.16>
> +})
> +
> +test:finish_test()