Literal Values in Conditions or Expressions
Conditions that you use in Where or Having clauses, as well as other expressions you can use in functions, can contain literal values. To have literal values recognized correctly, you must follow some basic rules based on the type of data for that literal:
String: literal values must be enclosed in single quote marks ( ' ) to distinguish them as a literal value rather than a query keyword or the name of a column or dataset. For example:
select lastname,state from congress where state = 'TX'
Numeric: literal values do not require any delimiters. Include the decimal point or sign characters, but other punctuation such as thousand separators is not required. For example:
select item,qty,price from invoices where price < 50.00
Date or Time: literal values usually require a casting function to ensure that they are properly recognized. For example:
select lastname, state, birthdate from congress
where birthdate <
to_date('1959/12/31','YYYY/MM/dd')