A database is an organized collection of data, where you can store and retrieve information. Most modern database management systems (DBMSs), also known as database servers, store data in tables.

Tables contain records, also known as rows. Each row contains fields, also known as columns. Every table in a database must have a unique name, and every column within a table must have a unique name. Each column in a table has a data type, which varies depending on the DBMS. For example, the following table contains columns for the unit under test (UUT) number, a step name, a step result, and a measurement.

UUT_NUM STEP_NAME RESULT MEAS
20860B456 TEST1 PASS 0.5
20860B456 TEST2 PASS (NULL)
20860B123 TEST1 FAIL 0.1
20860B789 TEST1 PASS 0.3
20860B789 TEST2 PASS (NULL)

A row can contain an empty column value, which means the specific cell contains a NULL value, also referred to as an SQL NULL value.

The order of the data in the table is not important. Ordering, grouping, and other manipulations of the data occur when you retrieve the data from the table. Use an SQL SELECT command, or query, to retrieve records from a database. The query defines the content and order of the data you want to retrieve. The result of a query is called a recordset or SQL Statement data. You can retrieve certain columns and rows from one table, or you can retrieve data from multiple tables. You can refer to each column you retrieve by the name of the column or by a one-based number that refers to the order of the column in the query.