In this example we convert to the datetime data type: SELECT CAST('' AS datetime) AS Result Result: Conversion failed when converting date and/or time from character string.Įxample 2 – Convert to datetime Data Type Just like with CONVERT() the string needs to be in a style that’s able to be converted to the specified data type, otherwise you’ll get an error: SELECT CAST('Homer' AS date) AS Result In this example, we convert the string into a date data type (we specify this by using date as the second argument). length An optional integer that specifies the length of the target data type. This includes xml, bigint, and sql_variant. These arguments are defined as follows: expression Any valid expression. The syntax goes like this: CAST ( expression AS data_type ) This article contains examples using the CAST() function. So if you need to convert a string to a date/time value, you can use the CONVERT() function or the CAST() function.Īnd if you get an error while using those two functions, the PARSE() function might be just what you need. This function works almost the same as the CONVERT() function, except that the syntax is slightly different (and CAST() doesn’t accept the style argument). In summary, the CONVERT function is a powerful tool for converting data from one type to another in SQL Server, but it should be used carefully to ensure that the conversion is valid for the given data.In SQL Server, you can use the CAST() function to convert an expression of one data type to another. SELECT TRY_CAST('ABC' AS INT) AS ConvertedValue This can be useful when dealing with data of uncertain or varied types. In such cases, you may need to use other functions like CONVERT or handle the conversion in your application code.Īdditionally, starting from SQL Server 2012, you can use the TRY_CAST function, which returns NULL if the cast is not possible instead of raising an error. For example, casting a non-numeric string to an integer would result in an error. It’s important to note that not all conversions are possible, and attempting to cast incompatible types may result in an error. In this case, the string ‘Hello’ is cast to a variable character string with a maximum length of 10 characters. Using Length Parameter SELECT CAST('Hello' AS VARCHAR(10)) AS ConvertedString The decimal value 15.75 is cast to an integer, and the fractional part is truncated. Here, a string representing a date is cast to the DATE data type.ĭecimal to Integer SELECT CAST(15.75 AS INT) AS ConvertedInteger In this example, the string ‘123’ is cast to an integer, resulting in the value 123.ĭate Conversion SELECT CAST('' AS DATE) AS ConvertedDate Let’s look at some examples to illustrate the use of the CAST function:īasic Usage SELECT CAST('123' AS INT) AS ConvertedValue The optional length parameter is used for types that require a length, such as VARCHAR or CHAR. Here, expression is the value you want to convert, and data_type is the target data type to which you want to convert the expression. The syntax for the CAST function is as follows: CAST (expression AS data_type ) This conversion can be necessary when you need to perform operations on data of different types or when you want to display data in a specific format. The SQL CAST function is used to convert an expression of one data type to another.
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