Left outer join in CAMl Query

Question

I want to use left outer join in my caml query in java script. I am little bit confused how to use joins. Please anyone explain an easy example of left outer join query in caml.

Answer 1

There is an excellent tool available to help with complex CAML queries in JS especially when working with joins: https://camljs.codeplex.com/

Joining lists via CamlJs is very easy. Here's the example:

var query = new CamlBuilder()
.View(["Title","Country","Population"])
.LeftJoin("Country","Country").Select("People","Population")
.Query()
.Where()
.NumberField("Population").LessThan(10)
.ToString();

Camljs will automatically generate the appropriate CAML query for you. So the resulting generated CAML query will be the following:

<View>
<ViewFields>
    <FieldRef Name="Title" />
    <FieldRef Name="Country" />
    <FieldRef Name="Population" />
</ViewFields>
<Joins>
    <Join Type="LEFT" ListAlias="Country">
        <Eq>
            <FieldRef Name="Country" RefType="ID" />
            <FieldRef Name="ID" List="Country" />
        </Eq>
    </Join>
</Joins>
<ProjectedFields>
    <Field ShowField="People" Type="Lookup" Name="Population" List="Country" />
</ProjectedFields>
<Query>
    <Where>
        <Lt>
            <FieldRef Name="Population" />
            <Value Type="Number">10</Value>
        </Lt>
    </Where>
</Query>