mysql - Repeat each value in SQL table n times with 1:n in different column

Mysql - Repeat each value in SQL table n times with 1:n in different column

If you want to repeat each value in an SQL table n times and store the result in a new column, you can use the CROSS JOIN approach to generate a sequence of numbers and then join it with the original table. Here's an example using MySQL:

Assuming you have a table named your_table with a column your_column, and you want to repeat each value n times and store the result in a new column repeated_column:

-- Adjust the values in the CROSS JOIN to determine how many times each value should be repeated -- In this example, each value is repeated 3 times SELECT your_column, repeated_value FROM your_table CROSS JOIN ( SELECT 1 AS repeated_value UNION ALL SELECT 2 UNION ALL SELECT 3 ) AS numbers;

This query creates a temporary table named numbers with values from 1 to 3 (you can adjust this range based on your requirement). The CROSS JOIN then combines each row in your_table with each row in numbers, effectively repeating each value n times.

If you want to store the repeated values in a new column, you can use the CONCAT function or another appropriate method:

-- Example using CONCAT to create a new column named 'repeated_column' SELECT your_column, CONCAT(your_column, '_', repeated_value) AS repeated_column FROM your_table CROSS JOIN ( SELECT 1 AS repeated_value UNION ALL SELECT 2 UNION ALL SELECT 3 ) AS numbers;

Adjust the number of repetitions and the method of combining values based on your specific requirements.

Examples

  1. "MySQL duplicate rows with a sequence number"

    • Description: Searches for ways to duplicate each row in a table with a sequence number to represent the repetition.
    SELECT id, value, ROW_NUMBER() OVER (PARTITION BY id ORDER BY id) AS repetition_number FROM your_table;

  2. "Repeat each value in SQL table using CROSS JOIN"

    • Description: Explores using CROSS JOIN to repeat each value in a table n times.
    SELECT t1.id, t1.value, t2.repetition FROM your_table t1 CROSS JOIN (SELECT 1 AS repetition UNION SELECT 2 UNION SELECT 3) t2;

  3. "SQL generate sequence numbers for each row"

    • Description: Demonstrates generating sequence numbers for each row to represent the repetition.
    SELECT id, value, ROW_NUMBER() OVER (ORDER BY id) AS repetition_number FROM your_table;

  4. "MySQL repeat rows with recursive common table expression (CTE)"

    • Description: Shows how to use a recursive CTE to repeat each row in a table.
    WITH RECURSIVE RepeatCTE AS ( SELECT id, value, 1 AS repetition FROM your_table UNION ALL SELECT id, value, repetition + 1 FROM RepeatCTE WHERE repetition < n ) SELECT * FROM RepeatCTE;

  5. "SQL repeat values using UNION ALL"

    • Description: Explores using UNION ALL to repeat each value in a table n times.
    SELECT id, value FROM your_table UNION ALL SELECT id, value FROM your_table UNION ALL ...

  6. "MySQL duplicate rows with CROSS JOIN and ROW_NUMBER()"

    • Description: Combines CROSS JOIN and ROW_NUMBER() to duplicate rows with sequence numbers.
    SELECT t1.id, t1.value, t2.repetition FROM your_table t1 CROSS JOIN (SELECT ROW_NUMBER() OVER () AS repetition FROM your_table) t2;

  7. "SQL generate row numbers for each value"

    • Description: Demonstrates generating row numbers for each value in the table.
    SELECT id, value, ROW_NUMBER() OVER (PARTITION BY value ORDER BY id) AS repetition_number FROM your_table;

  8. "Repeat each value in SQL table using JOIN and sequence table"

    • Description: Utilizes a sequence table joined with the original table to repeat each value.
    SELECT t1.id, t1.value FROM your_table t1 JOIN (SELECT 1 AS repetition UNION SELECT 2 UNION SELECT 3) t2 ON t2.repetition <= n;

  9. "MySQL duplicate rows with Cartesian Product"

    • Description: Explores using Cartesian Product to duplicate rows in the table.
    SELECT t1.id, t1.value, t2.repetition FROM your_table t1 JOIN (SELECT 1 AS repetition FROM your_table) t2;

  10. "SQL generate repeating sequence numbers for each value"

    • Description: Demonstrates generating repeating sequence numbers for each value in the table.
    SELECT id, value, ROW_NUMBER() OVER (PARTITION BY value ORDER BY id) AS repetition_number FROM your_table;

More Tags

basic-authentication null iconv facebook-login file-permissions npm-link popup-balloons file-conversion git-difftool simplewebrtc

More Programming Questions

More Math Calculators

More Mixtures and solutions Calculators

More Chemistry Calculators

More Weather Calculators