Hi Ramprakash,
It can be that your query doesn't return anything so there is no update.
You may fetch temp schema like this:
var schemaName = vars.targetSchema.substr(vars.targetSchema.indexOf(":") + 1);
logInfo(schemaName);
var query = xtk.queryDef.create(
<queryDef schema={vars.targetSchema} operation="select">
<select>
<node expr="firstName"/>
<node expr="lastName"/>
<node expr="email"/>
<node expr="city"/>
</select>
</queryDef>);
If you are sure in this above, you may try this for writing:
var some_variable= <customer
xtkschema="ram:customer"
_key="@firstName"
_operation="Update"
city = {record.city}
firstName={record.firstName}
/>;
xtk.session.Write(some_variable);