The Oracle PL/SQL CAST function is a type conversion function that is used to convert an expression of one data type to another data type. The CAST function allows you to explicitly convert the data type of an expression to the desired data type.
The syntax of the CAST function is as follows:
CAST(expression AS datatype)
In this syntax, the expression is the value that you want to convert to another data type, and the datatype is the data type to which you want to convert the expression. The datatype can be any valid Oracle data type, including numeric, character, and date/time data types.
For example, if you have a string value that represents a date in the format of “yyyy-mm-dd”, you can use the CAST function to convert it to a date data type as follows:
SELECT CAST(to_date('2023-04-08','yyyy-mm-dd') AS DATE) FROM DUAL;
This query will return the date value of “2023-04-08”.
Similarly, you can use the CAST function to convert a numeric value to a character data type as follows:
SELECT CAST(12345 AS VARCHAR2(10)) FROM DUAL;
This query will return the string value of “12345”.
In addition to the CAST function, Oracle also provides other type conversion functions, such as TO_CHAR, TO_NUMBER, and TO_DATE. The choice of which function to use depends on the specific data types and formatting requirements of your application.
In summary, the Oracle PL/SQL CAST function is a useful function for converting data types in Oracle databases. It allows you to explicitly convert the data type of an expression to another data type, and it can be used for a variety of data type conversions, including character, numeric, and date/time data types.