SQL Data Types

Filed Under: SQL

SQL Data Types define the type of value that can be stored in a table column. For example, if we want a column to store only integer values, then we can define it’s data type as int.

SQL Data Types

SQL data types can be broadly divided into following categories.

  1. Numeric data types such as int, tinyint, bigint, float, real etc.
  2. Date and Time data types such as Date, Time, Datetime etc.
  3. Character and String data types such as char, varchar, text etc.
  4. Unicode character string data types, for example nchar, nvarchar, ntext etc.
  5. Binary data types such as binary, varbinary etc.
  6. Miscellaneous data types – clob, blob, xml, cursor, table etc.

sql data types

SQL Data Types important points

  • Not all data types are supported by every relational database vendors. For example, Oracle database doesn’t support DATETIME and MySQL doesn’t support CLOB data type. So while designing database schema and writing sql queries, make sure to check if the data types are supported or not.
  • Data types listed here doesn’t include all the data types, these are the most popularly used data types. Some relational database vendors have their own data types that might be not listed here. For example, Microsoft SQL Server has money and smallmoney data types but since it’s not supported by other popular database vendors, it’s not listed here.
  • Every relational database vendor has it’s own maximum size limit for different data types, you don’t need to remember the limit. Idea is to have the knowledge of what data type to be used in a specific scenario.

Let’s look into different categories of sql data types in detail.

SQL Numeric Data Types

Datatype From To
bit 0 1
tinyint 0 255
smallint -32,768 32,767
int -2,147,483,648 2,147,483,647
bigint -9,223,372,036,854,775,808 9,223,372,036,854,775,807
decimal -10^38 +1 10^38 -1
numeric -10^38 +1 10^38 -1
float -1.79E + 308 1.79E + 308
real -3.40E + 38 3.40E + 38

SQL Date and Time Data Types

Datatype Description
DATE Stores date in the format YYYY-MM-DD
TIME Stores time in the format HH:MI:SS
DATETIME Stores date and time information in the format YYYY-MM-DD HH:MI:SS
TIMESTAMP Stores number of seconds passed since the Unix epoch (‘1970-01-01 00:00:00’ UTC)
YEAR Stores year in 2 digit or 4 digit format. Range 1901 to 2155 in 4-digit format. Range 70 to 69, representing 1970 to 2069.

SQL Character and String Data Types

Datatype Description
CHAR Fixed length with maximum length of 8,000 characters
VARCHAR Variable length storage with maximum length of 8,000 characters
VARCHAR(max) Variable length storage with provided max characters, not supported in MySQL
TEXT Variable length storage with maximum size of 2GB data

Note that all the above data types are for character stream, they should not be used with unicode data.

SQL Unicode Character and String Data Types

Datatype Description
NCHAR Fixed length with maximum length of 4,000 characters
NVARCHAR Variable length storage with maximum length of 4,000 characters
NVARCHAR(max) Variable length storage with provided max characters
NTEXT Variable length storage with maximum size of 1GB data

Note that above data types are not supported in MySQL database.

SQL Binary Data Types

Datatype Description
BINARY Fixed length with maximum length of 8,000 bytes
VARBINARY Variable length storage with maximum length of 8,000 bytes
VARBINARY(max) Variable length storage with provided max bytes
IMAGE Variable length storage with maximum size of 2GB binary data

SQL Miscellaneous Data Types

Datatype Description
CLOB Character large objets that can hold up to 2GB
BLOB For binary large objects
XML for storing xml data
JSON for storing JSON data

That’s all for a quick roundup on SQL data types.

Reference: Oracle Database Data Types, mySQL Data Types

Comments

  1. Rajaram says:

    Good Evening Shri.Pankaj Sir,

    very very useful & beneficial of your SQL lecture.
    Great thanks full for your Guide in SQL study materials.

    by Rajaram

  2. Saurabh Rawat says:

    Hello everyone here
    I am new at sql
    How can i insert data into a table which contain both Character and letter (For eg A001)
    Which datatype should i use here. Please let me know

    1. Pankaj says:

      Use varchar or varchar2 for string data.

  3. Mr SQL says:

    Type BIT is not a numeric data type, its binary. Also it is no longer part of SQL standard. So better to remove it.
    Type YEAR does not exist in SQL standard. Also never use year numbers with only 2 digits (remember year2k bug?)

    You miss the type BOOLEAN which can have values true or false. It is fundamentally different from BIT.
    You miss the type INTERVAL of which there are 2 basic ones: INTERVAL SECONDS (can include fractions) and INTERVAL MONTHS.

    Type TEXT and NTEXT are old synonyms for CLOB, so use CLOB (or CHARACTER LARGE OBJECT).
    Type IMAGE is an old synonym for BLOB, so use BLOB (or BINARY LARGE OBJECT).

  4. sadiqullah says:

    thank’s so much

  5. Blabla says:

    Very good my son..
    God bless you

  6. Shirajul says:

    Hello,

    Is it possible to enter an Array for a value in a table?

    Is there an ARRAY column type?

    Kind Regards,

    1. Sew says:

      But why?? I think better idea is create another table and make refference

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