Conversion functions in SQL are used to change the data type of a value. These functions are essential when handling different data formats and ensuring consistency in data processing.
Types of Conversion Functions
- CAST(): Converts an expression from one data type to another.
- CONVERT(): Similar to CAST but allows formatting for date and numeric conversions.
- TRY_CAST(): Similar to CAST but returns NULL instead of an error if conversion fails.
- TRY_CONVERT(): Functions like CONVERT but returns NULL if conversion fails.
- FORMAT(): Converts values into a formatted string.
Example Usage of Conversion Functions
1. Using CAST() Function
SELECT CAST(123.45 AS INT) AS ConvertedValue;
Output. 123
2. Using CONVERT() Function
SELECT CONVERT(VARCHAR, GETDATE(), 103) AS FormattedDate;
Output. 19/03/2025 (Example format for DD/MM/YYYY)
3. Using TRY_CAST() Function
SELECT TRY_CAST('123ABC' AS INT) AS Result;
Output. NULL (Fails due to non-numeric characters)
4. Using TRY_CONVERT() Function
SELECT TRY_CONVERT(INT, '456XYZ') AS Result;
Output. NULL (Fails due to non-numeric characters)
5. Using FORMAT() Function
SELECT FORMAT(1234567.89, 'N2') AS FormattedNumber;
Output. 1,234,567.89
Advantages of Conversion Functions
- Helps standardize data representation across databases.
- Allows formatting of numeric and date values.
- Prevents errors when handling mixed data types.