sql - Count occurrences in string via MySQL

Sql - Count occurrences in string via MySQL

In MySQL, you can count occurrences of a specific substring within a string using the LENGTH() and REPLACE() functions. Here's how you can do it:

Example:

Suppose you have a string your_string and you want to count the occurrences of a specific substring your_substring within it.

SELECT (LENGTH(your_string) - LENGTH(REPLACE(your_string, 'your_substring', ''))) / LENGTH('your_substring') AS occurrences_count FROM your_table;

Replace your_string, your_substring, and your_table with your actual string, substring, and table name respectively.

Explanation:

  • REPLACE(your_string, 'your_substring', '') replaces all occurrences of 'your_substring' with an empty string in your_string.
  • LENGTH(your_string) gives the total length of your_string.
  • LENGTH(REPLACE(your_string, 'your_substring', '')) gives the length of your_string after removing all occurrences of 'your_substring'.
  • Subtracting these two lengths gives the total length of all occurrences of 'your_substring'.
  • Dividing this by the length of 'your_substring' gives the count of occurrences.

Note:

  • This method works by comparing the lengths before and after replacement. It assumes that the length of 'your_substring' is not zero. If 'your_substring' can be zero-length, you need to handle it separately.
  • Make sure to adjust the function parameters and table names according to your specific use case.
  • This approach may not be the most efficient for large datasets or frequent use. If you need to perform such operations frequently or on large datasets, consider alternative approaches or optimizations.

Examples

  1. MySQL - Count occurrences of a substring in a string

    Description: Count occurrences of a specific substring within a string using LENGTH and REPLACE functions in MySQL.

    -- Example: MySQL - Count occurrences of substring in string SELECT (LENGTH(columnName) - LENGTH(REPLACE(columnName, 'substring', ''))) / LENGTH('substring') AS OccurrencesCount FROM tableName;

  2. MySQL - Count occurrences of a character in a string

    Description: Count occurrences of a specific character in a string using LENGTH and REPLACE functions in MySQL.

    -- Example: MySQL - Count occurrences of character in string SELECT LENGTH(columnName) - LENGTH(REPLACE(columnName, 'char', '')) AS OccurrencesCount FROM tableName;

  3. MySQL - Count occurrences of a word in a sentence

    Description: Count occurrences of a whole word (case-sensitive) in a sentence using LIKE and CONCAT functions in MySQL.

    -- Example: MySQL - Count occurrences of word in sentence SELECT (LENGTH(columnName) - LENGTH(REPLACE(columnName, ' word ', ''))) / LENGTH(' word ') AS OccurrencesCount FROM tableName;

  4. MySQL - Count occurrences of a substring ignoring case

    Description: Count occurrences of a substring (case-insensitive) using LOWER function in MySQL.

    -- Example: MySQL - Count occurrences of substring ignoring case SELECT (LENGTH(LOWER(columnName)) - LENGTH(REPLACE(LOWER(columnName), 'substring', ''))) / LENGTH('substring') AS OccurrencesCount FROM tableName;

  5. MySQL - Count occurrences of multiple substrings

    Description: Count occurrences of multiple substrings using multiple REPLACE functions in MySQL.

    -- Example: MySQL - Count occurrences of multiple substrings SELECT (LENGTH(columnName) - LENGTH(REPLACE(REPLACE(REPLACE(columnName, 'sub1', ''), 'sub2', ''), 'sub3', ''))) / LENGTH('sub1') AS OccurrencesSub1, (LENGTH(columnName) - LENGTH(REPLACE(REPLACE(REPLACE(columnName, 'sub1', ''), 'sub2', ''), 'sub3', ''))) / LENGTH('sub2') AS OccurrencesSub2, (LENGTH(columnName) - LENGTH(REPLACE(REPLACE(REPLACE(columnName, 'sub1', ''), 'sub2', ''), 'sub3', ''))) / LENGTH('sub3') AS OccurrencesSub3 FROM tableName;

  6. MySQL - Count occurrences of words with delimiters

    Description: Count occurrences of words delimited by spaces in a string using LIKE and CONCAT functions in MySQL.

    -- Example: MySQL - Count occurrences of words with delimiters SELECT (LENGTH(CONCAT(' ', columnName, ' ')) - LENGTH(REPLACE(CONCAT(' ', columnName, ' '), ' word ', ''))) / LENGTH(' word ') AS OccurrencesCount FROM tableName;

  7. MySQL - Count occurrences of pattern using REGEXP

    Description: Count occurrences of a pattern using REGEXP function in MySQL.

    -- Example: MySQL - Count occurrences of pattern using REGEXP SELECT COUNT(*) AS OccurrencesCount FROM tableName WHERE columnName REGEXP 'pattern';

  8. MySQL - Count occurrences of digits in a string

    Description: Count occurrences of digits in a string using REGEXP function in MySQL.

    -- Example: MySQL - Count occurrences of digits in string SELECT (LENGTH(columnName) - LENGTH(REPLACE(columnName, '[0-9]', ''))) AS OccurrencesCount FROM tableName;

  9. MySQL - Count occurrences of non-alphanumeric characters

    Description: Count occurrences of non-alphanumeric characters using REGEXP function in MySQL.

    -- Example: MySQL - Count occurrences of non-alphanumeric characters SELECT (LENGTH(columnName) - LENGTH(REPLACE(columnName, '[^a-zA-Z0-9]', ''))) AS OccurrencesCount FROM tableName;

  10. MySQL - Count occurrences of substring with overlap

    Description: Count occurrences of a substring allowing overlaps using recursive query in MySQL.

    -- Example: MySQL - Count occurrences of substring with overlap SELECT (CHAR_LENGTH(columnName) - CHAR_LENGTH(REPLACE(REPLACE(REPLACE(columnName, 'substring', '#'), '##', ''), '#', ''))) / CHAR_LENGTH('substring') AS OccurrencesCount FROM tableName;

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