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AskSQLTeam
Ask SQLTeam Question
0 Posts |
Posted - 2002-03-05 : 08:57:05
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| Alex writes "Hi Guys,I'm creating a online work station booking website for my campus.I need to create a SQL statement to display the stations available for booking for a given date and time provided by the user. Problem is my statement works on single entry of date and time but not for duplicating entries even when the systemnumbers are not the same. i.e. that is different work stations can be booked on the same day and time slot. Below is my table details and my current statement.System_data -----------systemnumber brand model operatingsystemBooking_data-------------systemnumbermemberidtimeslotbookeddatebookedif (select systemnumber from booking_data where datebooked = '3/2/2002' and timeslotbooked = '1800') is nullbeginselect * from system_data order by systemnumberendelsebeginselect * from system_data where systemnumber <> (select system_data.systemnumber from system_data inner join booking_data on system_data.systemnumber = booking_data.systemnumber where booking_data.datebooked = '3/2/2002' and booking_data.timeslotbooked = '1800') order by system_data.systemnumberendAny help please?Alex" |
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yakoo
Constraint Violating Yak Guru
312 Posts |
Posted - 2002-03-05 : 10:49:28
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You probably dont even need to do a check first. Try using a left or right outer join instead of an inner join and return the records that have null values for booking_data.Something like thisSELECT sd.* FROM System_data sd RIGHT OUTER JOIN Booking_data bd ON sd.Systemnumber = bd.Systemnumber WHERE bd.Systemnumber is NULL |
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