Search Artists by Name Pattern
A customer is looking for bands that start with "The" (like "The Beatles", "The Rolling Stones", etc.). You need to...
WHERELIKEPattern Matching
Beginner
4m10 pts
3397%
SQL Practice Hub
SQL String Functions Practice Questions
Cut, combine and match text values that arrive in the wrong shape.
9 questionsFreeRuns in your browser
- SUBSTR / POSITION
- Slice text by position.
- LIKE
- Simple pattern matching with % and _.
- Regex
- For patterns LIKE cannot express.
What you will practice
- Slice values with SUBSTR, LEFT, RIGHT and POSITION to pull a prefix, domain or code out of a field
- Build new labels by concatenating columns with || or CONCAT and handling NULL parts
- Match patterns with LIKE and ILIKE, including the % and _ wildcards and how to escape them
- Use regular expressions to extract or replace substrings that a wildcard cannot describe
- Standardise case and whitespace with UPPER, LOWER and TRIM before joining or grouping on text
Read the full overview
Text columns rarely arrive in the shape a report needs: names come combined, emails hide the domain, product codes carry a prefix. SQL string functions cut and rebuild those values in place, with SUBSTR and POSITION for slicing, concatenation for joining fields, LIKE for simple pattern matching and regular expressions when the pattern is not simple. These questions cover the parsing and matching problems that come up in interviews and in day-to-day cleanup work.
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FAQ
SQL String Functions practice: common questions
Short answers to what people get stuck on most. Tap a question to expand it.
How do I extract part of a string, like the domain of an email?
Split on a delimiter with SPLIT_PART, or slice with SUBSTR and POSITION.
- SUBSTR(text, start, length) is 1-based.
- POSITION('@' IN email) finds where the delimiter is.
- SPLIT_PART(email, '@', 2) returns the second piece in PostgreSQL.
SQL
SELECT email,
SPLIT_PART(email, '@', 2) AS domain,
SUBSTR(email, 1, POSITION('@' IN email) - 1) AS username
FROM users;When should I use LIKE and when regex?
Use LIKE for simple patterns. Use a regular expression when you need character classes or repeats.
- LIKE: % matches any number of characters, _ matches exactly one.
- ILIKE is the case-insensitive version in PostgreSQL.
- Regex in PostgreSQL uses ~ (for example phone ~ '^[0-9]{10}$').
- A leading % in LIKE cannot use a normal index.
SQL
SELECT *
FROM customers
WHERE phone ~ '^[0-9]{10}$'
OR name ILIKE 'a%';Why does concatenating with || return NULL?
In PostgreSQL, joining any value with NULL using || gives NULL.
- CONCAT treats NULL as an empty string.
- CONCAT_WS(sep, ...) skips NULLs and adds the separator only between real values (shown here).
- Use COALESCE if you want a specific fallback text.
SQL
SELECT CONCAT_WS(' ', first_name, middle_name, last_name) AS full_name
FROM users;Related practice topics
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