SQL Regular Expressions Quiz

What does REGEXP_LIKE(CustomerID, '^A') check?

• CustomerID ends with 'A'

• CustomerID contains 'A'

• CustomerID starts with 'A'

• Invalid syntax

Answer explanation

REGEXP_LIKE(CustomerID, '^A') checks if CustomerID starts with 'A'. The caret (^) indicates the start of the string, making 'CustomerID starts with 'A'' the correct choice.

What does REGEXP_INSTR(Manager, '[aeiou]') return?

• Count of vowels

• Position of first vowel

• TRUE/FALSE

• Replaces vowels

Answer explanation

REGEXP_INSTR returns the position of the first occurrence of a pattern in a string. In this case, it finds the position of the first vowel in 'Manager', making 'Position of first vowel' the correct answer.

What does this return: REGEXP_COUNT('Hello123', '[0-9]')?

• 0

• 3

• 1

• NULL

Answer explanation

The function REGEXP_COUNT counts the number of matches for the regex '[0-9]' in the string 'Hello123'. There are three digits (1, 2, and 3), so it returns 3, making '3' the correct answer.

Which function extracts a substring using a regex pattern?

• REGEXP_REPLACE

• SUBSTRING

• REGEXP_SUBSTR

• INSTR

Answer explanation

The function REGEXP_SUBSTR is specifically designed to extract substrings that match a given regex pattern, making it the correct choice. Other options like REGEXP_REPLACE and INSTR serve different purposes.

What does REGEXP_REPLACE(CustomerID, '[^A-Za-z]', '') do?

• Replaces alphabetic characters

• Removes all letters

• Keeps only letters

• Replaces NULL values

Answer explanation

REGEXP_REPLACE(CustomerID, '[^A-Za-z]', '') removes all non-alphabetic characters, effectively keeping only the letters. Therefore, the correct answer is 'Keeps only letters'.

What is returned by REGEXP_LIKE('R-1001', '^[A-Z]-\d{4}$')?

• TRUE

• FALSE

• Error

• 1001

Answer explanation

REGEXP_LIKE checks if 'R-1001' matches the pattern '^[A-Z]-\d{4}$'. The pattern requires a single uppercase letter, a hyphen, and exactly four digits. 'R-1001' meets these criteria, so it returns TRUE.

What does [[:digit:]] represent?

• Alphabetic characters

• Letters and digits

• Digits (0–9)

• Punctuation

Answer explanation

The notation [[:digit:]] is a regular expression that specifically matches any digit from 0 to 9. Therefore, the correct answer is 'Digits (0–9)', as it accurately describes what this expression represents.

What does REGEXP_REPLACE('AB-123', '[A-Z]', '*') return?

• AB-123

• **-123

• --123

• **123

Answer explanation

The REGEXP_REPLACE function replaces all uppercase letters (A-Z) in 'AB-123' with '*'. Thus, 'A' and 'B' are replaced, resulting in '**-123'. Therefore, the correct answer is '**-123'.

What’s the result of REGEXP_SUBSTR('abc123def', '[0-9]+')?

• abc

• 123

• def

• abc123

Answer explanation

The function REGEXP_SUBSTR extracts substrings matching a regular expression. Here, '[0-9]+' matches one or more digits. In 'abc123def', the first match is '123', making it the correct answer.

What does REGEXP_LIKE(OrderID, '[0-9]{3,}') check?

• OrderID has at least 3 digits

• Only 3-digit numbers

• Text-only IDs

• Null check

Answer explanation

REGEXP_LIKE(OrderID, '[0-9]{3,}') checks if OrderID contains at least 3 consecutive digits. Therefore, the correct choice is that OrderID has at least 3 digits.