商品コードからカテゴリだけ抜き出す、メールからドメインを取得する、ラベル用に複数の値を連結する――文字列処理は日常的に発生します。 まずは 部分取り出し（SUBSTR） と 連結（CONCAT） を、実務でよくある形で整理しておくのがおすすめです。

REGEXP_SUBSTR returns one occurrence of a substring of a string that matches the regular expression pattern.

Extracting categories from product codes, getting domains from email addresses, concatenating multiple values for labels—string processing is a daily occurrence. First, it is recommended to organize ...

SQL, LIKE vs. SUBSTR I came across a context where using the SUBSTR function yielded 10X less query runtime than LIKE The LIKE operator is used in the WHERE clause to search for a specific pattern in ...

🚀 Day 10 – SQL Single Row Functions Today I learned how to clean and transform data using functions --- 🔹 1. UPPER() 👉 Converts text to uppercase SELECT UPPER('sql'); Output: SQL --- 🔹 2. LOWER() ...