How to generate SQL with specific table columns using BQL - acumatica

Question

When I join two DAC in BQL syntax its generates SQL which selects all the columns from both tables. What if I want to select one table's columns in order to reach good execution plan?

Answer 1

You could try to look into PXProjection where the Columns are defined as the fields within the projection class. PXProjection is like a SQL view as a DAC in Acumatica. Just search the Acumatica source for PXProjection and you should find many examples. Note that within the class you need to set BqlField for each "column" so the process knows which table.field your projection field maps to.
Quick join PXProjection below. In this example there will be only 1 column in the DAC and it maps to APRegister.docType
[PXProjection(typeof(Select2<APRegister,
InnerJoin<APInvoice, On<APInvoice.docType, Equal<APRegister.docType>,
And<APInvoice.refNbr, Equal<APRegister.refNbr>>>,
InnerJoin<APPayment, On<APPayment.docType, Equal<APRegister.docType>,
And<APPayment.refNbr, Equal<APRegister.refNbr>>>>>,
Where<APRegister.docType, Equal<APDocType.quickCheck>,
Or<APRegister.docType, Equal<APDocType.voidQuickCheck>>>>), Persistent = true)]
[Serializable]
public partial class APQuickCheck : APRegister
{
#region DocType
public new abstract class docType : PX.Data.IBqlField
{
}
[PXDBString(3, IsKey = true, IsFixed = true, BqlField = typeof(APRegister.docType))]
[PXDefault(APDocType.QuickCheck)]
[APQuickCheckType.List()]
[PXUIField(DisplayName = "Type", Visibility = PXUIVisibility.SelectorVisible, Enabled = false)]
[PXFieldDescription]
public override String DocType
{
get
{
return this._DocType;
}
set
{
this._DocType = value;
}
}
#endregion
}