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Count occurrences of each character in a string

SQLeasy0.4 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
KPMG
Key Concepts Tested
bigquerysnowflakesparksql
Expert AnswerPremium
84 wordsInterview-ready
**Architectural Logic**: Character-level operations in SQL vary by engine; choose based on scale and frequency. **PostgreSQL**: `WITH chars AS (SELECT unnest(string_to_array('hello', null)) AS c) SELECT c, COUNT(*) FROM chars GROUP BY c`. **Spark**: `df.select(explode(split(col("str"), "")).alias("c")).groupBy("c").count()`. **BigQuery/Snowflake**: SPLIT, REGEXP_EXTRACT_ALL, or UDF. **Why It Matters**: SQL is not optimized for character iteration; at scale, consider application-layer or UDF....
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