sql - MS Access: How to use calculated field in a sub query? -

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i have problem following query 

select a.pname, (b.hours+c.hours) totalhours,    (select top 1 grade tabled tabled.hoursrequire >=**totalhours**)   tablea   left join tableb b on a.pname=b.pname   left join tablec c on a.pname=c.pname

my problem calculated field "totalhours" not recognized in sub query, appreciated.

will want using field expression (b.hours+c.hours) in subquery instead of alias totalhours?

select a.pname, (b.hours+c.hours) totalhours, (select top 1 grade tabled tabled.hoursrequire >= (b.hours+c.hours)) tablea left join tableb b on a.pname=b.pname left join tablec c on a.pname=c.pname

however you're using left joins, , suspect rows either b.hours or c.hours null, nothing subquery because b.hours+c.hours null , tabled.hoursrequire >= null never evaluate true. nz() function useful here.

edit: @cyberwiki spot on re top 1 without order by. sorry missed that.

why have hours split between 2 tables (tableb , tablec)? show sample data tables.

edit2: if it's impractical consolidate hours single physical table, can still "virtual" table using union query.

save qryunionhours:

select pname, hours tableb union select pname, hours tablec;

then can use qryunionhours data source group query, qryhoursperperson, totals hours each person.

select pname, sum(hours) totalhours qryunionhours group pname;

actually may prefer single query incorporates sql qryunionhours subquery. did 2 because thought might easier understand , less prone syntax errors. need integrate grade assignments discussed in other thread.


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