Beginner LevelSQL & MySQL
What built-in String Functions exist (CONCAT, SUBSTRING, LENGTH, LOWER)?
❓ Interview Prompt: Explain core SQL string functions: `CONCAT()`, `CONCAT_WS()`, `SUBSTRING()`, `LENGTH()` / `CHAR_LENGTH()`, `LOWER()`, and `REPLACE()`.
SQL provides built-in functions for manipulating string columns:
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'CONCAT(str1, str2, ...)': Joins multiple strings together ('CONCAT(first_name, ' ', last_name)').
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'CONCAT_WS(separator, str1, str2)': Joins strings with a designated separator.
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'SUBSTRING(str, pos, len)': Extracts a substring starting at character position 'pos'.
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'CHAR_LENGTH(str)': Returns character count (handles multi-byte UTF-8 properly).
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'LOWER(str)' / 'UPPER(str)': Converts text casing.
Code Implementation Example
sql
SELECT
id,
CONCAT_WS(' ', first_name, last_name) AS full_name,
LOWER(email) AS normalized_email,
SUBSTRING(zip_code, 1, 5) AS base_zip
FROM users;💡Formatting and transforming text columns using string functions.
🎯 Interview Key Takeaway
Use built-in string functions to format, normalize, and concatenate text columns directly inside SQL queries.
#SQL#String Functions#CONCAT#SUBSTRING#Beginner
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