在Mysql中生成Series，如何在查询时添加自动增量？

Question

I had a table with a column(c5) that contained a number x, I needed a SQL expression that repeated the same row x numbers of times:

My table A contained:

c1  c2  c3  c4  c5
16  1   2   16  3
16  1   2   17  2 
16  1   2   18  1

And I needed:

c1  c2  c3  c4  c5  n
16  1   2   16  3   1
16  1   2   16  3   2
16  1   2   16  3   3
16  1   2   17  2   1
16  1   2   17  2   2
16  1   2   18  1   1

Answer 1

I solved That with SQL expression:

SELECT
    c1, c2, c3, c4, c5, row_number AS n
FROM
    (
        SELECT
            @curRow := @curRow + 1 AS row_number
        FROM
            tablea
        JOIN (SELECT @curRow := 0) r
        WHERE
            @curRow < (
                SELECT
                    max(c5)
                FROM
                    tablea
            )
    ) AS vwtable2
LEFT JOIN tablea d ON vwtable2.row_number <= tablea.c5;