I have one table (tbl_employee) with many relations (tbl_relation), you can see it below :
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SELECT
tbl_employee.NAME,
tbl_employee.DATEOFBIRTH,
tbl_relation.CODEDESC
FROM
tbl_employee
INNER JOIN tbl_relation ON (tbl_employee.GENDER = tbl_relation.CODENAME)
AND (tbl_employee.INTEREST = tbl_relation.CODENAME)
AND (tbl_employee.YEARIN = tbl_relation.CODENAME)
WHERE
(tbl_relation.CODE = '01') AND
(tbl_relation.CODE = '02') AND
(tbl_relation.CODE = '03')
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I have an error when I execute my query.
Is my query correct? Help me, please ..

an error, eh?

perhaps you might share with us what that error was

in any case, the query will not produce any results

the WHERE clause specifies that each tbl_relation.CODE value must be equal to three different values at the same time

clearly, this is impossible

however, if you change the ANDs to ORs, then the WHERE clause makes sense

but the ON clause of the join suffers from the same problem

you want tbl_relation.CODENAME to be equal to three different tbl_employee column values

clearly, this is only possible when those three values are all equal to each other

and GENDER = INTEREST = YEARIN, while not strictly impossible, doesn't make much sense either