The evaluation of an expression returns a valuei.e. a numeric value, an alphanumeric value, a national value or a date and time value.
The data type of this value determines whether the expression is an alphanumeric expression, a national expression, a numeric expression or a date and time expression.
Expressions can occur in:
Column selection (SELECT expression, SELECT expression)
predicates in search conditions (e.g. WHERE clause, HAVING clause, IF clause)
assignments (INSERT, MERGE, UPDATE or SET statement)
An expression consists of the following operands and can include operators. The operators are used on the results of the operands.
values (see "Values")
as strings (alphanumeric and national literals)
as special literals
as host variables
as parameters
as local variables
as placeholders in SQL statements for dynamic compilation
columns (see "Column")
functions (see "Functions")
Time functions
Numeric functions
String functions
Aggregate functions
Table functions
Cryptographic functions
User Defined Functions (UDFs)
CASE expression (see "CASE expression")
CAST expression (see "CAST expression")
subqueries (see "Subquery")