AX 2012 - Multi Table lookup - Display Fields from Multiple table in a lookup

Multi Table lookup - Where you can set lookup field from multiple table by joining multiple table and create a multi table lookup using SysMultiTableLookup. 

here is the Demo of the below code:

    Query                   query;
    QueryBuildDataSource    InventTrans;
    QueryBuildDataSource    GroupItem;
    QueryBuildDataSource    EcoRes;

    SysMultiTableLookup sysTableLookup;
    query = new Query();

    InventTrans = query.addDataSource(tableNum(InventTable));
    InventTrans.addRange(fieldNum(InventTable, SL_IncludeInSchemes)).value(queryValue(NoYes::Yes));

    //join the translation table so we can get a description of the UOM
    EcoRes = InventTrans.addDataSource(tableNum(EcoResProductTranslation));
    EcoRes.joinMode(JoinMode::InnerJoin);
    EcoRes.relations(false);
    EcoRes.addLink(fieldNum(InventTable,Product),fieldNum(EcoResProductTranslation,Product));

    //join the translation table so we can get a description of the UOM
    GroupItem = InventTrans.addDataSource(tableNum(InventItemGroupItem));
    GroupItem.joinMode(JoinMode::InnerJoin);
    GroupItem.relations(false);
    GroupItem.addLink(fieldNum(InventTable,ItemId),fieldNum(InventItemGroupItem,ItemId));
    GroupItem.addLink(fieldNum(InventTable,DataAreaId),fieldNum(InventItemGroupItem,ItemDataAreaId));

    //filter by the unit class being passed
    GroupItem.addRange(fieldNum(InventItemGroupItem, ItemGroupId)).value(queryValue(smmParametersTable::find().SL_SchemeReleaseItemGroup));

    //define multiple table lookup query
    sysTableLookup  = SysMultiTableLookup::newParameters(_formControl, query);
    //add which fields will be displayed to the user (symbol + desc.)
    sysTableLookup.addLookupfield(fieldNum(InventTable, ItemId), true);
    sysTableLookup.addLookupfield(fieldNum(EcoResProductTranslation, Name), 2);
    //do not use for multi table
    //sysTableLookup.parmQuery(query);
    sysTableLookup.performFormLookup();

AX 2012 - Multi Table Lookup - Join many multi with root table to display a lookup on root table

Lookup table on form datasource field. Here is the code for multi table look.

public void lookup(FormControl _formControl, str _filterStr)
{
    Query                                query           = new Query();
    QueryRun                         QueryRun;
    QueryBuildDataSource    reasoncode;
    QueryBuildDataSource    inventTransWMS;
    SysTableLookup               sysTableLookup;
    ;

    super(_formControl, _filterStr);


    if(TmpInventTransWMS.InventQty < 0)
    {
        reasoncode  = query.addDataSource(tableNum(SL_TransferOrderReasonCode));

//<tag>Repeat<tag>
        inventTransWMS = reasoncode.addDataSource(tableNum(SL_InventTransWMS));
        inventTransWMS.fetchMode(JoinMode::ExistsJoin);

        inventTransWMS.relations(false);
        inventTransWMS.addLink(fieldNum(SL_TransferOrderReasonCode, Code),fieldNum(SL_InventTransWMS, SL_TransferOrderReasonCode));

        inventTransWMS.addRange(fieldNum(SL_InventTransWMS, InventDim)).value(queryValue(TmpInventTransWMS.InventDimId));
        inventTransWMS.addRange(fieldNum(SL_InventTransWMS, InventTransOrigin)).value(queryValue(InventTrans::findRecId(TmpInventTransWMS.InventTrans).InventTransOrigin));
        inventTransWMS.addRange(fieldNum(SL_InventTransWMS, InventTransOrigin)).value(queryValue(InventTrans::findRecId(TmpInventTransWMS.InventTrans).InventTransOrigin));

//you can add more data set by repeat from <tag>repeat</tag> tag.

        sysTableLookup = SysTableLookup::newParameters(tableNum(SL_TransferOrderReasonCode), _formControl);
        sysTableLookup.addLookupfield(fieldNum(SL_TransferOrderReasonCode, code));
        sysTableLookup.addLookupfield(fieldNum(SL_TransferOrderReasonCode, codeDescription));

        sysTableLookup.parmQuery(query);
        sysTableLookup.performFormLookup();
    }
}