What is the difference between cast and convert in sql server

Many client applications, including those based on Automation objects, use a cutoff year of This allows for the consistent treatment of dates. We recommend specifying four-digit years. When casting character data representing only date or only time components to the datetime or smalldatetime data types, the unspecified time component is set to Z indicates time zone UTC For example: T When converting smalldatetime to character data, the styles that include seconds or milliseconds show zeros in these positions.

When converting from datetime or smalldatetime values, use an appropriate char or varchar data type length to truncate unwanted date parts. When converting character data to datetimeoffset , using a style that includes a time, a time zone offset is appended to the result. For a float or real expression , style can have one of the values shown in the following table. For a money or smallmoney expression , style can have one of the values shown in the following table.

For an xml expression , style can have one of the values shown in the following table. For a binary n , char n , varbinary n , or varchar n expression , style can have one of the values shown in the following table. Style values not listed in the table will return an error. The following illustration shows all explicit and implicit data type conversions allowed for SQL Server system-supplied data types.

The above chart illustrates all the explicit and implicit conversions that are allowed in SQL Server, but the resulting data type of the conversion depends on the operation being performed:.

A practical example on the effects of data type precedence in conversions can be seen later in this section. When you convert between datetimeoffset and the character types char , nchar , nvarchar , and varchar , the converted time zone offset part should always have double digits for both HH and MM. For example, Because Unicode data always uses an even number of bytes, use caution when you convert binary or varbinary to or from Unicode supported data types.

For example, the following conversion does not return a hexadecimal value of For more information, see Collation and Unicode Support. Large-value data types have the same implicit and explicit conversion behavior as their smaller counterparts - specifically, the nvarchar , varbinary , and varchar data types. However, consider the following guidelines:. When you explicitly or implicitly cast the xml data type to a string or binary data type, the content of the xml data type is serialized based on a defined set of rules.

The text and image data types do not support automatic data type conversion. You can explicitly convert text data to character data, and image data to binary or varbinary , but the maximum length is bytes.

If you try an incorrect conversion, for example trying to convert a character expression that includes letters to an int , SQL Server returns an error message.

If the input is not a character string, the output has the default collation of the database, and a collation label of coercible-default. For example:. When converting character or binary expressions binary , char , nchar , nvarchar , varbinary , or varchar to an expression of a different data type, the conversion operation could truncate the output data, only partially display the output data, or return an error.

These cases will occur if the result is too short to display. Conversions to binary , char , nchar , nvarchar , varbinary , or varchar are truncated, except for the conversions shown in the following table. SQL Server guarantees that only roundtrip conversions, in other words conversions that convert a data type from its original data type and back again, yield the same values from version to version. The following example shows such a roundtrip conversion:. Do not construct binary values, and then convert them to a data type of the numeric data type category.

SQL Server does not guarantee that the result of a decimal or numeric data type conversion, to binary , will be the same between versions of SQL Server. When you convert data types that differ in decimal places, SQL Server will sometimes return a truncated result value, and at other times it will return a rounded value.

This table shows the behavior. For example, the values These two functions are part of the Microsoft SQL server and play a part in the conversion of data. Both these functions are used to convert data from one format to another, but are different from each other in a few ways.

The main function of the software is to store and retrieve data that is requested by other software applications, no matter where they are running. In order to create SQL Server 1. By the 4. Firstly, there are two ways that data is converted in the SQL server, implicit and explicit.

Implicit conversion includes that the server automatically converts the data without requiring the user to input any external data or coding. However, much of the data falls in the explicit section, where the server requires the user to specify how they want the data to be converted.

Thought their syntax is different, both functions are able to convert values from one formation to another. The numbers shown in red are the style formatter. There are many style formats you can use.

The complete list is here. There are several reasons I can think of:. What do you think? I would love to know. Please post in the comments which function you would rather use and why. Kris Wenzel has been working with databases over the past 30 years as a developer, analyst, and DBA.