Page 52 - DCAP402_DCAO204_DATABASE MANAGEMENT SYSTEM_MANAGING DATABASE

Unit 3: Structured Query Language

“column3” “data type” Notes
[constraint]);
[ ] = optional

Notes You may have as many columns as you’d like, and the constraints are optional.

Lab Exercise create table employee
(first varchar(15),
last varchar(20),
age number(3),
address varchar(30),
city varchar(20),
state varchar(20));
To create a new table, enter the keywords create table followed by the table name, followed by
an open parenthesis, followed by the first column name, followed by the data type for that
column, followed by any optional constraints, and followed by a closing parenthesis. It is
important to make sure you use an open parenthesis before the beginning table, and a closing
parenthesis after the end of the last column definition.
Make sure you seperate each column definition with a comma. All SQL statements should end
with a “;”.
The table and column names must start with a letter and can be followed by letters, numbers, or
underscores - not to exceed a total of 30 characters in length. Do not use any SQL reserved
keywords as names for tables or column names (such as “select”, “create”, “insert”, etc.).

Data types specify what the type of data can be for that particular column. If a column called
“Last_Name”, is to be used to hold names, then that particular column should have a “varchar”
(variable-length character) data type.

3.7 DML Operations

Various DML (Data Manipulation Language) commands
1. SELECT used to select different columns
2. INSERT to put the data into tables

3. UPDATE to modify the data
4. DELETE to delete the data.

3.7.1 SELECT Command

SELECT command consists of expressions and strings. In the general form of basic SQL query,
the select-list consists of:

1. Expressions and
2. Column name

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