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Primary keys

Last modified: 20 December 2022

A primary key contains unique values and identifies each row in a table.

For some databases, the primary key cannot contain NULL values. A table can have only one primary key and this primary key can consist of single or multiple columns. When a primary key consists of multiple columns, the data from these columns is used to determine whether a row is unique.

Primary keys can be seen in the Database tool window. You can see a reference on node and object icons in the Icons for data sources and their elements chapter of Database tool window topic.

For the table column icons, refer to Possible icon combinations for columns.