Standard/Structured Query Language

San José State University Department of Economics

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Standard/Structured* Query Language

*In the early days of the system there was divided preference between Standard Query Language and Structured Query Language but it did not make a whole lot of difference since most people most of the time called it by the acronym SQL. Now the overwhelming but not complete preference is for Structured Query Language.

The syntax of SQL statements is simple although inelegant. The most important type is a SELECT query, which is of the form:

SELECT Select_List
FROM table_names_list
[WHERE search_creteria]
[ORDER BY column_criteria [ASC | DESC] ]

Explanation
The Select_List (fields names separated by commas) determines which fields (columns) appear in the resulting table.
The table_names_list in the FROM gives the table or tables that are used in forming the resulting table.
The search_criteria in the optional WHERE line gives the condition, if any, for including a particular row in the tabulation.
The optional ORDER BY line tells how the results should be arranged (ordered) and the column to be used for the ordering and whether it should be an ascending or descending ordering.

There are qualifiers which may precede the Select_List. These qualifiers are of the form
[ALL | DISTINCT | DISTINCTROW] [ TOP n [PERCENT]]

which determine whether all rows or only distinct rows will be used. The selection can also be limited to the top n or the top n percent of the rows.

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