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Lesson 10

Tables Rows Database Conclusion

In this module, we discussed tables, databases, rows and columns as the elements that make up a relational database system. You also created a table, figured out how to add an index, inserted information into the table, and queried the table to see the information you inserted.
It is important to understand firmly what each item refers to. The exact syntax for creating the tables can be referenced by the version of SQL that you are implementing.
You need to make sure you understand the specific process and the end result that you are trying to achieve. You will need to fully understand the differences between tables, databases, rows and columns to effectively build SQL statements. These are key elements not only in the course project and examples, but also in the everyday use of SQL.

Summary of Relational Database Elements

  1. a table is an organized set of data elements using a model of vertical columns (which are identified by their name) and horizontal rows.
  2. The cell of a table is the unit where a row and column intersect.
  3. A table has a specified number of columns, but can have any number of rows.
  4. Each row is identified by the values appearing in a particular column subset which has been identified as a unique key index.
  5. Table is another term for relation; although there is the difference in that a 1) table is usually a multiset of rows and 2) a relation is a set that does not allow duplicate elements.
Besides the actual data rows, tables generally have metadata associated with them, such as constraints on the table or values within particular columns. The data in a table does not have to be physically stored in the database. Views are also relational tables and their data is calculated at query time.