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The Ultimate Guide to Know More About SQL Data Type

Table of Content: –

  1. What is Data Type?
  2. • Types of SQL Data
  3. • Exact Numeric
  4. • Unicode Character Strings
  5. • Approximate Numeric
  6. • Binary Strings
  7. • Date and Time
  8. • Character strings

In SQL Server, every column is defined by the local variable, expression, and parameter related to their data type. In simple language, a data type is an attribute that specifies the type of data that the object can handle. For example, integer data, character data, financial data, date and time, binary strings, etc.

This Server supplies a set of system data types that define all the data types that can be used inside the SQL Server. Moreover, you can define your own data types in Transact-SQL or the Microsoft .NET Framework by yourself as well.

To know it from the inside, let’s understand it briefly. For example, Alias data types are based on the system supplied to the data types. Often, when a user defines types with the help of their characteristics by the methods and operators of a class that he created with the help of programming languages supported by the .NET Framework.

In a case, where two expressions having different data types, collations, precision, scale, or length, are combined by the user, the characteristics of the result are determined by the following:

  1. Through this, the data type of the result is found by applying the rules of data type precedence to the data of the input expressions.
  2. In this, the collation of the result is determined by the rules of collation precedence when the result data type is char, varchar, text, nchar, nvarchar, or ntext.
  3. The precision, scale, and length of the result depend on the input expressions’ precision, scale, and length.

The SQL contains a lot of data types and not everyone knows everything about all the data types. So, let’s know more about the most significant & useful data types of SQL server.

Data Type Categories

In SQL Server, the data types are organized into the following categories:

  • · Exact numeric
  • · Unicode character strings
  • · Approximate numeric
  • · Binary strings
  • · Date and time
  • · Other data types
  • · Character strings

Apart from all that, SQL Server also works on the basis of storage characteristics. Some data types are also designated as belonging to the following groups: –

  • • Large value data types: varchar(max), and nvarchar(max)
  • • Large object data types: text, ntext, image, varbinary(max), and xml

Exact Numeric

Working with any kind of database ultimately means working with data. Exact Numeric data can take a couple of predefined formats.

For example, let’s say we have a table of “users”. Every user has different information in their name and phone number. In this, names are stored in the character column and a phone number in a numerical column.

So, numerical columns store numbers, and if you think all numbers are the same, you are completely wrong & you need to guess again. There are various types of numbers, and there are several types of numerical columns. If you have a past in statistics, you must know that four different scales apply to numbers: nominal, ordinal, interval, and ratio.

Moreover, unlike any other data type in SQL, numerical types can represent all of these scales.

Unicode Character Setting

In simple terms, UNICODE means uniform character encoding standard. A UNICODE character can only be used for multiple bytes to store the data in the database. It means that using UNICODE is only possible for processing characters of various writing systems in a single document. This could be useful if you’re working with an international character set (for example, different languages).

The SQL Server supports three UNICODE data types. The three types of the data type are: –

  1. NEAR
  3. NEXT

Approximate Numeric

In the SQL data type, the approximate numeric data types consist of NUMERIC (p, s) as well as DECIMAL (p, s) subtypes. They are exact, and the user only defines them by precision (p) and scale (s). Here, precision is an integer representing the total number of digits available in the column. These digits are in a particular radix or number base that is binary or decimal. They are usually defined with a decimal point & they are the reason why this data type of SQL is called approximate numeric.

The scale, also an integer value, represents the number of decimal places to the decimal point’s right (if positive) or left (if negative). But there is only a rare chance where the decimal point gets negative most of the time.

Let’s look at an example to understand it better. Suppose that you defined a balance column as numeric with a precision of 8 and a scale of 2.

Binary String

A binary string is not only about the binary, but it also contains Varbinary. These are the binary string data types present in the SQL Server. In most cases, these data types are used to store raw binary data up to a length of 32K – 1 byte. They also contain content of image files BMP, TIFF, GIF, or JPEG format files, word files, text files, etc. are also some examples of binary data.

Date and time

It is one of the common types of data type in the SQL server, but that doesn’t make it easy. The DATE-TIME data type stores an instant time expressed as a calendar date and time of day. In this data type, the user must select how precisely a DATETIME value will be stored in their server. Moreover, its precision can range from a year to a fraction of a second.

DATETIME stores a data value as a contiguous series of fields representing each time unit, For example, year, month, day, second & son on for the data type declaration. To understand it better, let’s take an example. You can enter a MONTH TO HOUR value in a column declared as YEAR TO MINUTE if each entered value contains information for a contiguous series of time units. However, you cannot enter a value for only the MONTH and HOUR; the entry must include a value for DAY as well.

Character String

The character string data types contain CHAR, VARCHAR, Binary, VARBINARY. BLOB, TEXT, ENUM, & SET. Apart from all that, in some cases of a character string, the SQL can change a string column to a type different from that given in a create table or alter table statement.

Moreover, the character string column can also work for char, varchar, and text types. The SQL only interprets length & specifications contained in the character unit.

Column definitions for character string data type CHAR, VARCHAR the text types, ENUM, SET, and (any other synonyms). It can specify the column character set and collation. Moreover, the CHARACTER SET specifies the character set as well. If desired, a collation for the character set can be specified with the COLLATE attribute and any other attributes.

For example, any table creates a column named c1 with a character set of utf8 with the default collation for that character set and a column named c2 with a character set of latin1 and a case-sensitive collation.

The rules for assigning the character set and collation when either or both of CHARACTER SET and the COLLATE attribute are missing are described in Section 10.3.5

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