How to duplicate returning values from a query in MySQL-CodePudding

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How to duplicate returning values from a query in MySQL

Time：08-16

When I use this I Get the table two times but I want each value duplicated before the next value comes

SELECT *
FROM student
WHERE major LIKE 'C%'
UNION ALL
SELECT *
FROM student
WHERE major LIKE 'C%';

CodePudding user response：

You can use a union all. A union will not work, because it will eliminate duplicates. Another way is a cross join:

select 
    *
from 
    students t1 cross join
     (select 1 as n union all select 2) n
        WHERE major LIKE 'C%'
        order by id;