McDewey

General Concepts This section gives a brief overview of relational database concepts and details about how data is generated by the system software. Tables Columns and Rows A database contains tables of data. A table defines a series of columns or fields. The actual data is stored as rows or records within each table. Each row contains one value for each column of the table. For example, Figure 1 shows a table with five columns. It contains three rows of data. The data in tables changes for each system, but the definition of tables and columns does not. This manual describes the columns of each table; it does not describe the actual data in table rows. Table Relationships Related tables in a database share one or more common fields or columns. For example, both the Agent and Peripheral tables include the PeripheralID field. This defines a relationship: each row in the Agent table is related to the row in the Peripheral table that shares the same PeripheralID value. Relationships between tables can be one-to-one or one-to-many. For example, because one peripheral can be associated with many agents, the relationship between the Peripheral and Agent tables is one-to-many. On the other hand, each peripheral has a single peripheral default route and each peripheral default route belongs to only one peripheral. Therefore, the relationship between the Peripheral and Peripheral Default Route tables is one-to-one. Sometimes a single row might not be associated with any rows in a related table. For example, it is possible to define a peripheral with no associated agents. Usually, this would only be a temporary condition. In some cases, however, the condition might be permanent. For example, you can define a trunk group but not define the associated trunks. Sometimes the natural relationship between two tables appears to be many-to-many. For example, each agent can be a member of many skill groups and each skill group can contain many agents. Therefore, the Agent and Skill Group tables appear to have a many-to-many relationship. However, in this case, a third table, called a cross-reference table, actually links the tables so the relationship is actually one-to-many. For example, Figure 2 shows how the Skill Group Member table acts as a cross-reference table for the Agent and Skill Group tables. Database Schema Handbook for Cisco Unified Contact Center Enterprise, Release 15.0(1) 2 Introduction General Concepts