Computer Science 1032A/B Lecture Notes - Lecture 20: Query Language, Microsoft Access, Computer Language

• School: Western University
• Department: Computer Science
• Course: Computer Science 1032A/B
• Professor: Louis Magguilli

Document Summary

Queries in access: processes sql query language. Query: provides a subset of a table based on a criteria. Design tool: graphical interface to create queries, generates sql statement. To build a query, need to know: names of all of the entities involved in the query, relationships between the entities, criteria that control the retrieval of data. Queries allow us to ask questions about data. The record set that answers the question is called a dataset. Ansi* standard computer language for accessing & manipulating database systems. Sql statements retrieve & update data in a database. Sql works with database programs: ms access, db2, sql server, oracle, etc. Same attribute name may exist in more than one table so the notation to uniquely identify attributes in tables use: Example: attribute name exists in both the student table and the course table, refer to name attribute in the student table by student. name. Description of joining tables when retrieving data.