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Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-02 |
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# Expression Lists

An expression list is a combination of other expressions.

expression_list::=

Description of the illustration expression_list.gif

Expression lists can appear in comparison and membership conditions and in `GROUP` `BY` clauses of queries and subqueries.

Comparison and membership conditions appear in the conditions of `WHERE` clauses. They can contain either one or more comma-delimited expressions or one or more sets of expressions where each set contains one or more comma-delimited expressions. In the latter case (multiple sets of expressions):

- Each set is bounded by parentheses

- Each set must contain the same number of expressions

- The number of expressions in each set must match the number of expressions before the operator in the comparison condition or before the `IN` keyword in the membership condition.

A comma-delimited list of expressions can contain no more than 1000 expressions. A comma-delimited list of sets of expressions can contain any number of sets, but each set can contain no more than 1000 expressions.

The following are some valid expression lists in conditions:

    (10, 20, 40)
    ('SCOTT', 'BLAKE', 'TAYLOR')
    ( ('Guy', 'Himuro', 'GHIMURO'),('Karen', 'Colmenares', 'KCOLMENA') )

In the third example, the number of expressions in each set must equal the number of expressions in the first part of the condition. For example:

    SELECT * FROM employees
      WHERE (first_name, last_name, email) IN
      (('Guy', 'Himuro', 'GHIMURO'),('Karen', 'Colmenares', 'KCOLMENA'))

See Also: "Comparison Conditions" and IN Condition conditions

In a simple `GROUP` `BY` clause, you can use either the upper or lower form of expression list:

    SELECT department_id, MIN(salary), MAX(salary) FROM employees
       GROUP BY department_id, salary;

    SELECT department_id, MIN(salary), MAX(salary) FROM employees
       GROUP BY (department_id, salary);

In `ROLLUP`, `CUBE`, and `GROUPING` `SETS` clauses of `GROUP` `BY` clauses, you can combine individual expressions with sets of expressions in the same expression list. The following example shows several valid grouping sets expression lists in one SQL statement:

    SELECT
    prod_category, prod_subcategory, country_id, cust_city, count(*)
       FROM  products, sales, customers
       WHERE sales.prod_id = products.prod_id
       AND sales.cust_id=customers.cust_id
       AND sales.time_id = '01-oct-00'
       AND customers.cust_year_of_birth BETWEEN 1960 and 1970
    GROUP BY GROUPING SETS
      (
       (prod_category, prod_subcategory, country_id, cust_city),
       (prod_category, prod_subcategory, country_id),
       (prod_category, prod_subcategory),
        country_id
      );

See Also: SELECT