1. A computer-implemented method comprising: receiving, by a computer server system and as having been sent from a client device, a request for information that specifies relationships of a first person, wherein the request includes: (i) information that identifies the first person, and (ii) information that indicates a user-specified number of relationship separations extending from the first person from which other persons are to be identified; automatically creating, by the computer server system and in response to receiving the request, a single database query that: (i) when executed, causes a database system to identify a particular group of persons in a relational database that are related to the first person due to the particular group of persons being within the user-specified number of relationship separations from the first person, and (ii) is structured to cause the database system to identify the particular group of persons by: (a) identifying a first group of persons in the relational database to include in the particular group of persons, the identifying of the first group of persons including an identification of persons who are directly related, through a single relationship type from among multiple relationship types, to the first person, and (b) identifying additional persons in the relational database to add to the particular group of persons by performing, for each relationship separation in the user-specified number of relationship separations that extend from the identified first group of persons, a database left join operation that joins a respective additional group of persons in the relational database who are directly related, through the single relationship type, to any person in a previously joined group of persons until the number of relationship separations extending from the first person, through the single relationship type, is determined to satisfy the user-specified number of relationship separations indicated in the request, wherein performing a first of the database left join operations comprises identifying a first additional group of multiple persons to add to the particular group of persons, wherein the first additional group of multiple persons are identified for addition to the particular group of persons based on the first additional group of multiple persons being directly related to the persons in the first group of persons and also being indirectly related to the first person; providing, by the computer server system and to the database system in response to receiving the request, the single database query for execution by the database system, and in response, receiving results obtained by the database system from execution of the single database query, wherein the results specify the particular group of persons, wherein the database system is configured to execute the single database query in-memory; generating, by the computer server system and based on the results obtained by the database system, the information that specifies the relationships of the first person; and providing, by the computer server system and to the client device in response to receiving the request, the information that specifies the relationships of the first person for display.