Scalar Conversion Functions

Conversion functions transform an expression from one data type to another. They are essential for ensuring data compatibility and for formatting output.

Supported Functions

Function	Purpose	Syntax
`CAST`	Convert an expression to a specified data type.	`CAST ( expression AS data_type [ ( length ) ] )`
`CONVERT`	Similar to `CAST` but supports style codes for date/time and binary conversions.	`CONVERT ( data_type [ ( length ) ], expression [, style ] )`
`TRY_CAST`	Returns `NULL` when conversion fails instead of raising an error.	`TRY_CAST ( expression AS data_type [ ( length ) ] )`
`TRY_CONVERT`	Same as `TRY_CAST` with style support.	`TRY_CONVERT ( data_type [ ( length ) ], expression [, style ] )`
`PARSE`	Parse a string to a date/time or numeric value using culture information.	`PARSE ( string_value AS data_type [ USING culture ] )`
`TRY_PARSE`	Returns `NULL` on parsing failure.	`TRY_PARSE ( string_value AS data_type [ USING culture ] )`

Style Codes for `CONVERT`

When converting dates or binary data, specify a style code to control the output format.

SELECT CONVERT(varchar, GETDATE(), 101)   -- 06/25/2025
SELECT CONVERT(varchar, GETDATE(), 112)   -- 20250625
SELECT CONVERT(varbinary, 'ABC', 2)       -- 0x414243

Examples

Basic CAST

SELECT CAST('123' AS int) AS IntegerValue;
-- Result: 123

CONVERT with style

SELECT CONVERT(varchar(10), OrderDate, 101) AS USFormatDate
FROM Orders;
-- Returns dates as MM/DD/YYYY

TRY_CAST handling bad data

SELECT TRY_CAST('ABC' AS int) AS Result;   -- Result: NULL

PARSE using culture

SELECT PARSE('12,5' AS decimal(10,2) USING 'fr-FR') AS FrenchDecimal;
-- Result: 12.5