SQL Topic
String Functions
String questions use LENGTH, SUBSTR, REPLACE, UPPER/LOWER, TRIM, and LIKE to inspect and transform text columns.
When is String Functions used?
Validating tweet lengths, pattern matching on names or emails, normalizing text before grouping.
Core syntax
LENGTH(col), SUBSTR(col, start, len), UPPER(col), col LIKE 'pattern%'.Common mistakes
- Using LEFT/RIGHT from other dialects instead of SUBSTR.
- Case-sensitivity surprises with LIKE (SQLite's LIKE is case-insensitive for ASCII).
- Forgetting trailing spaces matter in comparisons.
Practice String Functions questions
Work through them in order — each question builds on the last.