SQL Functions
3 Topics
1
String Functions
Using UPPER, LOWER, CONCAT, LENGTH, and SUBSTRING.
String manipulation functions are tested in SQL interviews to evaluate data transformation skills — formatting names, cleaning data, extracting substrings, and building dynamic strings.
2
Numeric Functions
Using ROUND, CEIL, FLOOR, ABS, MOD, and other mathematical functions.
Numeric functions are tested in SQL interviews for rounding/truncation logic, financial calculations, bucketing data, and understanding the difference between ROUND, CEIL, FLOOR, and TRUNC behavior with negative numbers.
3
Date and Time Functions
Using CURRENT_DATE, CURRENT_TIMESTAMP, AGE, DATE_TRUNC, EXTRACT, and interval math.
Date/time functions are heavily tested in SQL interviews — computing durations, filtering by date ranges, truncating to periods, handling time zones, and understanding the difference between timestamp and timestamptz are all common topics.