How to Convert Varchar to Data Type Int?

How to Convert Varchar to Data Type Int?

Converting a varchar data type to an int data type is a common requirement in many programming scenarios. This conversion allows you to manipulate and perform arithmetic operations on the data stored as varchar.

However, it is important to note that not all varchar values can be successfully converted into an int. In this tutorial, we will explore different methods to convert varchar to int and handle potential errors that may arise.

Method 1: Using the CAST Function

The CAST function is a powerful tool in SQL that allows you to convert one data type to another. To convert a varchar value into an int using the CAST function, use the following syntax:

CAST(varchar_column_name AS int)

For example, if you have a table called “myTable” with a column named “myColumn” of type varchar, you can convert its values into integers with the following query:

SELECT CAST(myColumn AS int) FROM myTable;

Remember that this method may throw an error if the conversion is not possible due to invalid characters or non-numeric values in the varchar column.

Method 2: Using the CONVERT Function

Similar to the CAST function, the CONVERT function can also be used for converting varchar data types into ints. The syntax for using CONVERT is as follows:

CONVERT(int, varchar_column_name)

Using our previous example, here’s how you can convert values from “myColumn” into ints using CONVERT:

SELECT CONVERT(int, myColumn) FROM myTable;

Like with CAST, non-numeric characters or invalid entries in the varchar column may result in conversion errors.

Handling Conversion Errors

To handle conversion errors and prevent your queries from failing, you can use the ISNUMERIC function. ISNUMERIC returns 1 if the input expression is a valid numeric value and 0 otherwise. You can combine it with a CASE statement to handle non-numeric values gracefully.

Here’s an example that demonstrates how to use ISNUMERIC along with CASE:

SELECT
CASE
WHEN ISNUMERIC(myColumn) = 1 THEN CONVERT(int, myColumn)
ELSE NULL
END AS ConvertedValue
FROM myTable;

This query will return the converted int value if the varchar value is numeric, and NULL otherwise.

Conclusion

Converting varchar values to int is a common task in programming, especially when dealing with databases. By using either the CAST or CONVERT function along with proper error handling techniques, you can successfully convert varchar values into ints and perform arithmetic operations on them. Remember to validate the data before conversion to avoid unexpected errors.