Teach Yourself SQL in 21 Days, Second Edition
  
Week 2 In Review
Week 1 spent a great deal of time introducing a very important topic: the SELECT
statement. Week 2 branched out into various topics that collectively form a thorough
introduction to the Structured Query Language (SQL).
Day 8 introduced data manipulation language (DML) statements, which are SQL statements
that you can use to modify the data within a database. The three commands most commonly
used are INSERT, DELETE, and UPDATE. Day 9 described how
to design and build a database and introduced the commands CREATE DATABASE
and CREATE TABLE. A table can be created with any number of fields, each
of which can be a database-vendor-defined data type. The ALTER DATABASE
command can change the physical size or location of a database. The DROP DATABASE
and DROP TABLE statements, respectively, remove a database or remove a table
within a database.
Day 10 explained two ways to display data: the view and the index. A view is a
virtual table created from the output of a SELECT statement. An index orders
the records within a table based on the contents of a field or fields.
Day 11 covered transaction management, which was your first taste of programming
with SQL. Transactions start with the BEGIN TRANSACTION statement. The COMMIT
TRANSACTION saves the work of a transaction. The ROLLBACK TRANSACTION
command cancels the work of a transaction.
Day 12 focused on database security. Although the implementation of database security
varies widely among database products, most implementations use the GRANT
and REVOKE commands. The GRANT command grants permissions to a
user. The REVOKE command removes these permissions.
Day 13 focused on developing application programs using SQL. Static SQL typically
involves the use of a precompiler and is static at runtime. Dynamic SQL is very flexible
and has become very popular in the last few years. Sample programs used Dynamic SQL
with the Visual C++ and Delphi development toolkits.
Day 14 covered advanced aspects of SQL. Cursors can scroll through a set of records.
Stored procedures are database objects that execute several SQL statements in a row.
Stored procedures can accept and return values. Triggers are a special type of stored
procedure that are executed when records are inserted, updated, or deleted within
a table.
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