Question: I am developing site using PHP and backend ClickHouse database. When i using like queries , it is not supporting case-sensitive words. 

```
select id,comments from discussion where  comments LIKE "%Data not reflect%";

```

Is there any way to search case-insensitive words?

Answer: 
There's no `ILIKE` operator. I think you can use `lowerUTF8()`.

```sql
select id,comments from discussion where lowerUTF8(comments) LIKE '%Data not reflect%';

```

However, might be performance heavy as it will have to convert all `comments` values to lowercase.
Use `positionCaseInsensitive` or `positionCaseInsensitiveUTF8`

Just like that 

```
SELECT id,comments
FROM discussion
WHERE positionCaseInsensitive(comments,'Data not reflect')>0;

```

For more complicated patterns you can use regular expression with `i` flag inside: 

```
SELECT ... WHERE match(comment, '(?i)Data.*not reflect');

```

See documentation: <https://clickhouse.yandex/docs/en/query_language/functions/string_search_functions/#position-haystack-needle-locate-haystack-needle>