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What are LOWER, UPPER, LENGTH in SQL? String functions for beginners

String functions are a daily SQL tool: case normalization (LOWER, UPPER), length (LENGTH), whitespace trimming (TRIM), substrings (SUBSTRING), replace (REPLACE). Plain words: case-insensitive search, data cleanup, and Unicode gotchas.

1 min readSQL · string · functions · tutorial

These are the three most basic string functions. LOWER converts to lowercase, UPPER to uppercase, LENGTH counts the length. Plain, but exactly where real data work begins: email normalization, whitespace cleanup, case-insensitive search.

This article is currently in Russian. The full English translation is on the way.

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