[Solved]-C# Linq to find a record that matches a condition, if that record is found return all related records-LINQ,C#

try this query, just this query.

    var results2 = this.account_trans
                   .include(at => at.account_table1)
                   .include(at => at.account_table2)
                   .include(at => at.account_table3)
                   .include(at => at.account_table4)
                   .where(at => this.account_trans
                            .where(a => at.completion_date.value.day == date.day &&
                                a.completion_date.value.month == date.month &&
                                a.completion_date.value.year == date.year)
                            .select(a => a.fk_account).contains(at.fk_account))
                   .tolist();