SQL Data Types and Literals

SQL Data Types:

Every field or column in a table is given a data type when a table is defined. These data types describe the kind of information which can be stored in a column.

In SQL, this is done by assigning each field a data type that indicates the kind of values the field will contain. All the values in a given field must be of the same type.

There are commonly five types of data type in SQL:
i. CHAR
ii. VARCHAR
iii. NUMBER
iv. DATE
v. LONG

CHAR:

A column defined with a CHAR data type is allowed to store all types of characters which include letters both uppercase and lowercase letters, such as – A, B, …, Z and a, b, …, z and special characters like @, #, &, $, etc.

VARCHAR (size):

It is similar to CHAR but it can store variable sized string having a maximum length determined by ‘size’. The maximum value the ‘size’ can have is 2000 characters.

NUMBER (p, s):

It is used to store variable-length numeric data. The value of p determines the total number of digits possible to the left of the decimal point. The second value s determines the total number of digits possible to the right of the decimal point.

DATE:

This type of data is used to store date and time information. The default format is DD-MM-YY.

LONG:

This data type stores variable length character strings containing up to 2 gigabytes size. But LONG data type has some following limitations: