What are the three hardware components of a client/server system? (Chapter 1 Objective)
clients
server
network
Describe the way a client accesses
... [Show More] the database on a server using these terms: application software, data access API, database management system, SQL query, and query results. (Chapter 1 Objective)
Application software uses the data that's stored on a server and it does that using a data access API. The client communicates with a server via SQL queries that are passed through DBMS through the API. When the client sends a query the DBMS interprets the query and sends it back.
Describe the way a relational database is organized using these terms: tables, columns, rows, cells, primary keys, and foreign keys.(Chapter 1 Objective)
A relational database consist of tables. Tables have rows and columns. A column is an attribute of an entity and a row is a set of values for a single instance. Cells are the intersections of rows and columns that store a single value. A primary key is a single column that identifies each row in a table.
Identify the three types of relationships that can exist between two tables. (Chapter 1 Objective)
One-to-many relationship
One-to-one relationship
Many-to-many relationship
Describe the way the columns in a table are defined using these terms: data type, null value, and default value. (Chapter 1 Objective)
The data type that's assigned to a column determines the type of information that can be stored in the column.
The column information determines whether or not it can contain null values.
A column can be defined with a default value which is used when another value isn't provided.
Describe the difference between DML statements and DDL statements. (Chapter 1 Objective)
DML stands for data manipulation language and DDL stands for data definition language
Describe the difference between an action query and a SELECT query. (Chapter 1 Objective)
A SELECT query retrieves data and an action query alters it.
List three coding techniques that can make your SQL code easier to read and maintain. (Chapter 1 Objective)
Capitalize all keywords.
Use lowercase for the other code.
Separate the words in names with underscores.
Start each clause on a new line.
Break long clauses into multiple lines.
Indent continued lines.
Use comments only for code that is hard to understand.
Make sure that the comments are correct and up-to-date.
Explain how views and stored procedures differ from SQL statements that are issued from an application program. (Chapter 1 Objective)
Describe the use of a database driver. (Chapter 1 Objective)
What are clients?
Clients are the PCs, Macintoshes, or workstations of the system
What is a server?
A server is a computer that stores the files and databases of the system and provides services to the clients.
When it stores databases, it's often referred to as a database server.
What is a network?
consists of the cabling, communication lines, and other components that connect the clients and the servers of the system
How does a web application work?
Web browser on a client sends a request to a web server.
Web server processes the request.
Web server passes any data requests to the database server.
Database server returns results to web server.
Web server returns a response to the browser.
sequence
Result table (result set)
the result of a select statement is a result table, or result set
calculated values
are calculated from columns in table
query
a select statement is commonly referred to as a query
join
when a SELECT statement retrieves data from two tables and is joined into a single result set
inner join
rows from two tables are included in the result only if their related columns match
outer joins
lets you include all rows from a table even if the other table doesn't have a matching row
action query
queries that add, change or delete data (INSERT, UPDATE, DELETE)
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