FIELD
Field is a column of a table. Field has the size of a
particular data type that determines how the data will be saved.
The properties of the field is as follows:
1.
As the Primary key
attribute of Primary is the least that can distinguish each row of
data in a table is uniquely selected based on frequently used as a reference,
more concise, and more guarantee a unique key.
Example: NIM students is the
primary key of the table student. Nim has the function to be
linked with other tables that have relationships.
linked with other tables that have relationships.
2.
As the Foreign key
Foreign Key is a column taken from the
primary key of another entity that shows the relationship between the two
tables.
Example: if a user input the department
code 10, whereas in the database does not exist such a code, then the code will
be rejected. Foreign key also serves to prevent the manipulation of data by
parties who are not responsible.
3.
No same field.
4. AutoIncrement
No field - specific fields that do not need
to fill, but the system will fill in data to those fields.
e.g. serial number, system will automatically
fill in the serial number and any data will increase in value.
5. Has a default value
if we do not put the data fields in the
table, then we can provide default values for those fields.
6. Auto compute
sometimes we need a calculation,
for example, we enter the amount of
purchases of goods 9, while the price of an item @3000 then the total field
can be filled automatically by calculating the total amount of purchases by multiplying the purchase price per unit.
7. Nullable
The data in a field can be blank. The term
in the database is NULL. NULL is not equal to zero. Opponents of null is not
null.
RECORD
Record is a collection of the contents of the data elements (attributes)
that are interconnected to inform you about a complete entity.
Often called the line a table, containing data of each column of the
table.
Statement in sql divided into 3 categories:
1. Data Definition Language (DDL)
Support the definition section of a table such as the creation, deletion and modification of tables.
Support the definition section of a table such as the creation, deletion and modification of tables.
2. Data Manipulation Language (DML)
Allows users to process or manipulate the database, query example
INSERT, UPDATE, and DELETE
3. Retrieving Data
Display data, it is a SELECT query.
For the next will be discussed in this article.
References :
Sistem
Basis Data,Utami Ema | Anggit Dwi Hartanto, 2012, Yoyakarta, Andi.
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