200 N. Santaquin Utah
Johnson Brian 113 N. 1111 E. Rigby Idaho
Corry Jason 57 E. Wrangler San Antonio Texas
Using the SQL language, you can create queries that return specific data from the database.
For example, suppose you were to compose the following query:
SELECT Last FROM Contacts
The database would return the following data:
Last
Coughanour
Johnson
Corry
CHAPTER 29 Managing Databases 590
In addition to creating queries, the SQL language allows you to update, insert, and delete
records. This is done using the following commands:
. SELECT??”Retrieves information from a table
. UPDATE??”Modifies information in a table
. DELETE??”Removes information from a table
. INSERT??”Adds new data to a table
In addition to manipulating data within a table, SQL commands can also be used to
manage the table itself. This is done using the following commands:
. CREATE TABLE??”Creates a new table
. ALTER TABLE??”Modifies an existing table
. DROP TABLE??”Deletes an existing table
A key feature of a relational database is that you can create relations between tables,
which enables you to create powerful interrelated data sets.
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