How can I compare two dates in Oracle?
The correct way to do the date comparison is: WHERE ORDER_DATE = TO_DATE(’07-JUN-2000′,’DD-MON-YYYY’,’NLS_DATE_LANGUAGE=ENGLISH’); It will use the index on the ORDER_DATE column, so it will much better in terms of performance. Also, it is comparing dates and not strings.
Can we use SELECT statement in CASE Oracle?
Moreover, using the CASE function, multiple conditions provided in separate SQL queries can be combined into one, thus avoiding multiple statements on the same table (example given below). …
How to use CASE in SELECT query Oracle?
SELECT table_name, CASE owner WHEN ‘SYS’ THEN ‘The owner is SYS’ WHEN ‘SYSTEM’ THEN ‘The owner is SYSTEM’ END FROM all_tables; With the ELSE clause omitted, if no condition was found to be true, the CASE statement would return NULL.
How to use CASE condition in Oracle?
Oracle CASE expression allows you to add if-else logic to SQL statements without having to call a procedure. The CASE expression evaluates a list of conditions and returns one of the multiple possible results. You can use a CASE expression in any statement or clause that accepts a valid expression.
How can I compare two timestamps in Oracle?
To calculate the difference between the timestamps in Oracle, simply subtract the start timestamp from the end timestamp (here: arrival – departure ). The resulting column will be in INTERVAL DAY TO SECOND . The first number you see is the number of whole days that passed from departure to arrival .
Can we use SELECT query in case statement?
The case statement in SQL returns a value on a specified condition. We can use a Case statement in select queries along with Where, Order By, and Group By clause. Once a condition is satisfied, its corresponding value is returned.
Can you put a SELECT statement in a case statement?
The CASE expression is a conditional expression: it evaluates data and returns a result. The result it returns is based on whether the data meets certain criteria. This expression can be used in SELECT , UPDATE , and DELETE statements or in WHERE , IN , LIKE , ORDER BY , and HAVING clauses.
Can case statement return multiple values?
@yzhang – With CASE only the first match will return values. If you want the possibility of multiple conditions mathcing each input row, you need to make each check indpendantly, and UNION the results together.
Can we use CASE statement in having clause?
The value of the sum of the case statement must also be not equal to zero so it is used in the HAVING clause. However, an additional SUM is added to the script.
Does a case statement need an else?
The CASE statement always goes in the SELECT clause. CASE must include the following components: WHEN , THEN , and END . ELSE is an optional component.
Can CASE statement return multiple values?
Which is an example of a case expression in Oracle?
For example, you can use the CASE expression in statements such as SELECT, UPDATE, or DELETE, and in clauses like SELECT, WHERE, HAVING, and ORDDER BY. Oracle CASE expression has two formats: the simple CASE expression and the searched CASE expression. Both formats support an optional ELSE clause.
When does Oracle not evaluate a comparison expression?
Oracle does not evaluate all comparison expressions before comparing any them with the expression (e). As the result, Oracle never evaluates a comparison expression if a previous one equals the input expression (e).
When to return NULL value in Oracle CASE expression?
If the input expression e does not match any comparison expression, the CASE expression returns the expression in the ELSE clause if the ELSE clause exists, otherwise, it returns a null value. Oracle uses short-circuit evaluation for the simple CASE expression.
When to use a case expression in a statement?
The CASE expression evaluates a list of conditions and returns one of the multiple possible results. You can use a CASE expression in any statement or clause that accepts a valid expression.