How to Convert Data Type in Db2?

How to Convert Data Type in Db2?

Db2 is a powerful and versatile database management system that allows you to store, manipulate, and retrieve data efficiently. Often, while working with Db2 databases, you may need to convert data from one data type to another.

Understanding how to perform data type conversions in Db2 is essential for ensuring the accuracy and integrity of your database. In this tutorial, we will explore various methods of converting data types in Db2.

1. CAST Function

The CAST function in Db2 allows you to convert a value from one data type to another. It is particularly useful when you need to convert numeric values into strings or vice versa.

To use the CAST function, follow this syntax:

SELECT CAST(column_name AS new_data_type)
FROM table_name;

For example, let’s say you have a column named “price” with a numeric data type, and you want to convert it into a string:

SELECT CAST(price AS VARCHAR(10))
FROM products;

Example Output:

• “10.99”
• “5.99”
• “14.99”

2. TO_CHAR Function

The TO_CHAR function in Db2 is used to convert a numeric or date/time value into a character string with a specified format.

To use the TO_CHAR function, follow this syntax:

SELECT TO_CHAR(column_name, 'format')
FROM table_name;

For example, let’s say you have a column named “order_date” with a date/time data type, and you want to convert it into a string in the format ‘YYYY-MM-DD’:

SELECT TO_CHAR(order_date, 'YYYY-MM-DD')
FROM orders;

Example Output:

• “2022-01-01”
• “2022-01-02”
• “2022-01-03”

3. CASE Statement

The CASE statement in Db2 allows you to perform conditional data type conversions. It is handy when you need to convert values based on specific conditions.

SELECT column_name,
       CASE
           WHEN condition1 THEN value1
           WHEN condition2 THEN value2
           ELSE default_value
       END AS new_column_name
FROM table_name;

For example, let’s say you have a column named “rating” with an integer data type, and you want to convert it into a string representation based on its value:

SELECT rating,
       CASE
           WHEN rating = 1 THEN 'Poor'
           WHEN rating = 2 THEN 'Fair'
           WHEN rating = 3 THEN 'Good'
           ELSE 'Unknown'
       END AS rating_text
FROM reviews;

Example Output:

• “Fair”
• “Good”
• “Poor”

In conclusion, understanding how to convert data types in Db2 is crucial for manipulating and analyzing your database effectively. The CAST function, TO_CHAR function, and CASE statement are powerful tools that enable you to convert values accurately according to your requirements. By utilizing these methods appropriately, you can ensure the integrity and consistency of your data.