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Cartesian multiplication in SQL and update null columns

Time:06-19

I have these two tables in MySQL database:

tbl_hashs >

h_id r_id hash
1 122 xx
2 123 xx

tbl_sandbox >

h_id r_id hash
NULL NULL xx

finally I want to have this table:

query result should be like >>>

h_id r_id hash
1 122 xx
1 123 xx
2 122 xx
2 123 xx

I think something like "Cartesian multiplication" can help me. but I can't do it in MySQL. please somebody help me with proper query.

CodePudding user response:

SELECT
   t1.h_id,
   t2.r_id,
   t2.hash
FROM tbl_hashs t1
CROSS JOIN tbl_hashs t2
ORDER BY t1.h_id

But I did not use tbl_sandbox, is that good ?

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=32926caddc063c2adcbc03944ce489ce

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