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Home/Questions/SQL/Duplicate characters in a string (e.g., '123a!' to '112233aa!!').

Duplicate characters in a string (e.g., '123a!' to '112233aa!!').

SQLmedium0.3 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
HashedIn
Key Concepts Tested
joinpythonsparksql
Expert AnswerPremium
64 wordsInterview-ready
**Architectural Logic**: Character duplication is a string transform; SQL capabilities vary. **PostgreSQL**: `SELECT regexp_replace('123a!', '(.)', '\1\1', 'g')`. **Spark**: `regexp_replace(col("str"), "(.)", "$1$1")`. **Python**: `''.join(c*2 for c in s)`. **Why Choose**: SQL regex works in many dialects; application layer clearer for complex manipulation. **Scalability**: For bulk, prefer batch processing in Spark/Python; SQL for inline transforms....
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