Explicit Data Type Conversion

SQL Provides 3 functions to convert a value from one data type to another:

TO_CHAR (number | date, [, fmt] ) 

This function converts a number or date value to a VARCHAR2 character string with format model fmt.

TO_NUMBER (char, [fmt] )

This function converts a character string containing digits to a number in the format specified by the optional format model fmt.

TO_DATE (char, [fmt] )

This function converts a character string representing a date to a date according to the fmt specified. If fmt is omitted, the format is DD-MON-YY.

Using the TO_CHAR Function with Dates

TO_CHAR(date,'format_model')

The format model:

• Must be enclosed in single quotation marks and is case sensitive.
• Can include any valid date format element.

Example: 

TO_CHAR ( number,'format_model')

Example: here you can notice the both sal and salary printed with formatted result.

Note:

TO_NUMBER()

and TO_DATE()  

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