What are SQL Data Types ?

When you create a database with SQL Server, using the most accurate data type of the table columns you create will prevent many different problems, as well as the loss of lost data. If you want to start learning the database, you should first understand what SQL Data Types are and start by learning the difference between them.

 

The name of each column in a database table that you create and SQL Data Types allow you to keep the data types that this column can hold, such as monetary, date and time, and integer data.

 

SQL Data Types and Descriptions

When a database administrator or developer creates a table, that table should come to him and wish to choose the type of data that he will store. The data type is a directive for SQL, whichever type of data is not expected in the column, where you think about how SQL is directed to the stored information.

 

There are 3 different data types in SQL. These are string, ie text, number and date data types.

 

SQL String Data Types

Data Type Description Max. Size Storage
char(n) Fixed-width character string 8,000 characters Defined width
varchar(n) Variable width character string 8,000 characters 2 bytes + number of chars
varchar(max) Variable width character string 1,073,741,824 characters 2 bytes + number of chars
text Variable width character string 2GB of text data 4 bytes + number of chars
nchar Fixed width Unicode string 4,000 characters Defined width x2
nvarchar Variable width Unicode string 4,000 characters
nvarchar(max) Variable width Unicode string 536,870,912 characters
ntext Variable width Unicode string 2GB of text data
binary(n) Fixed width binary string 8,000 bytes
varbinary Variable width binary string 8,000 bytes
varbinary(max) Variable width binary string 2GB
image Variable width binary string 2GB

 

SQL Number Data Types

Data Type Description Storage
bit Integer that can be 0, 1, or NULL
tinyint Allows whole numbers from 0 to 255 1 byte
smallint Allows whole numbers between -32,768 and 32,767 2 bytes
int Allows whole numbers between -2,147,483,648 and 2,147,483,647 4 bytes
bigint Allows whole numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807 8 bytes
decimal(p,s) Fixed precision and scale numbers.

Allows numbers from -10^38 +1 to 10^38 –1.

The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18.

The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0

5-17 bytes
numeric(p,s) Fixed precision and scale numbers.

Allows numbers from -10^38 +1 to 10^38 –1.

The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18.

The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0

5-17 bytes
smallmoney Monetary data from -214,748.3648 to 214,748.3647. 4 bytes
money Monetary data from -922,337,203,685,477.5808 to 922,337,203,685,477.5807 8 bytes
float(n) Floating precision number data from -1.79E + 308 to 1.79E + 308.

The n parameter indicates whether the field should hold 4 or 8 bytes. float(24) holds a 4-byte field and float(53) holds an 8-byte field. Default value of n is 53.

4 or 8 bytes
real Floating precision number data from -3.40E + 38 to 3.40E + 38 4 bytes

 

SQL Date Data Types

Data Type Description Storage
datetime From January 1, 1753 to December 31, 9999 with an accuracy of 3.33 milliseconds 8 bytes
datetime2 From January 1, 0001 to December 31, 9999 with an accuracy of 100 nanoseconds 6-8 bytes
smalldatetime From January 1, 1900 to June 6, 2079 with an accuracy of 1 minute 4 bytes
date Store a date only. From January 1, 0001 to December 31, 9999 3 bytes
time Store a time only to an accuracy of 100 nanoseconds 3-5 bytes
datetimeoffset The same as datetime2 with the addition of a time zone offset 8-10 bytes
timestamp Stores a unique number that gets updated every time a row gets created or modified. The timestamp value is based upon an internal clock and does not correspond to real time. Each table may have only one timestamp variable

 

SQL Other Data Types

Data Type Description
sql_variant Stores up to 8,000 bytes of data of various data types, except text, ntext, and timestamp
uniqueidentifier Stores a globally unique identifier (GUID)
xml Stores XML formatted data. Maximum 2GB
cursor Stores a reference to a cursor used for database operations
table Stores a result-set for later processing

I know the data types above are intimidating. Yes, it may scare, but it is important to learn them one by one in order of use. In this series of education, we will prefer to learn in a memorable way by learning slowly and not by memorization. What are the SQL Data Types in your search ?

 

If you want to learn them all at once, this learning work will cause you to confuse them all and get tired of the concept of database quickly. That’s why future developers will be the best option to walk this path with confidence because we will be.

Leave a Reply

Your email address will not be published. Required fields are marked *