MySQL CAST() Function

 The CAST() function in MySQL is used to explicitly convert a value from one data type to another. This is helpful when you need to ensure that a value is treated as a specific type, such as converting a string to a number or a date.

Syntax:

CAST(expression AS target_data_type)

Parameters:

• expression: The value or column to be converted.
• target_data_type: The data type to convert the expression to. Examples include CHAR, DATE, DATETIME, SIGNED, UNSIGNED, DECIMAL, etc.

Commonly Used Data Types:

• String types: CHAR(n) or CHAR
• Numeric types: SIGNED, UNSIGNED, DECIMAL(n, d)
• Date/Time types: DATE, DATETIME, TIME

Examples:

1. Convert a number to a string:

SELECT CAST(12345 AS CHAR);

Output: '12345' (as a string)

2. Convert a string to a number:

SELECT CAST('12345' AS UNSIGNED);

Output: 12345 (as an integer)

3. Convert a string to a date:

SELECT CAST('2024-12-24' AS DATE);

Output: '2024-12-24' (as a date)

4. Convert to a decimal with precision:

SELECT CAST(12345 AS DECIMAL(10, 2));

Output: 12345.00

5. Using CAST() with a column:

SELECT name, CAST(age AS UNSIGNED) AS age_numeric FROM users;

This converts the age column to an unsigned integer.

Notes:

1. If the conversion fails (e.g., converting non-numeric characters to a number), MySQL may return 0 or NULL depending on the context.
2. For implicit conversions, MySQL often converts data types automatically, but CAST() allows for precise control.

Let me know if you'd like to see examples specific to your use case!