What is the function of the CAST function in Oracle?

In Oracle, the CAST function is used to convert a value of one data type into another data type. It is able to perform type conversion on data types such as numeric, character, date, etc.

The syntax of the CAST function is as follows:

CAST(expr AS data_type)

In this case, expr is the expression to be converted, and data_type is the target data type to convert to.

The following functions can be achieved using the CAST function.

1. Convert a data type value to another data type in a query to meet the needs of the query.
2. Convert a string to a number, or convert a number to a string.
3. Convert a date string to a date type, or convert a date type to a string type.
4. Convert a string type to a Large Object (LOB) type (CLOB or BLOB).
5. Convert a larger numeric type to a smaller one, or convert a smaller numeric type to a larger one.

It is important to note that the CAST function can only be used to convert between specific data types, such as numeric, character, and date types. If the data type being converted is not supported, or the expression being converted is invalid, it will result in a conversion failure and an exception will be thrown.