How do you write a case statement in a select query?
SQL Case Statement Syntax Then for a single condition you can write the keyword WHEN followed by the condition that has to be satisfied. After that comes the keyword THEN and the value for that condition, like WHEN THEN . This can then be followed by other WHEN / THEN statements.
Can I use CASE statement in where clause?
CASE can be used in any statement or clause that allows a valid expression. For example, you can use CASE in statements such as SELECT, UPDATE, DELETE and SET, and in clauses such as select_list, IN, WHERE, ORDER BY, and HAVING.
Can we use CASE statement in where clause in DB2?
If search-condition in a searched-when-clause specifies a quantified predicate or an IN predicate that includes a fullselect, the CASE expression cannot be used in the following contexts: select lists….simple-when-clause:
| CASE expression | Equivalent expression |
|---|---|
| CASE WHEN e1 IS NOT NULL THEN e1 ELSE e2 END | COALESCE(e1,e2) |
How do you use a case statement?
The CASE statement goes through conditions and returns a value when the first condition is met (like an if-then-else statement). So, once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause.
Can I use a case statement in a where clause?
Is null in DB2 case statement?
If no case evaluates to true and the ELSE keyword is not present, the result is NULL….simple-when-clause:
| CASE expression | Equivalent expression |
|---|---|
| CASE WHEN e1 IS NOT NULL THEN e1 ELSE e2 END | COALESCE(e1,e2) |
| CASE WHEN e1 IS NOT NULL THEN e1 ELSE COALESCE(e2,…,eN) END | COALESCE(e1,e2,…,eN) |
How do I add a case statement in SQL?
You can use the CASE expression to insert data into a SQL Server table. The INSERT statement with CASE will scan for the required values and if found, insert values from THEN expression.
Can we use case statement in WHERE clause?
Can CASE Statement return multiple values?
Of course I can write the case condition multiple times, each time return one value. However, as I have many condition need to fit, say 100. It is not good to repeat case condition again and again.
How do you use Db2 in case statement?
In this syntax, Db2 compares the expression in the CASE clause with each expression ( expression_1, expression_2, …) in the WHEN clause sequentially from top to bottom. Db2 returns the corresponding result in the THEN clause ( result_1, result_2, …) if it finds a match ( expression = expression1, expression = expression2 …).
How to update column DeptName in table using CASE statement?
Example 1: Use a simple case statement WHEN clause to update column DEPTNAME in table DEPT, depending on the value of SQL variable v_workdept. CASE v_workdept WHEN ‘A00’ THEN UPDATE DEPT SET DEPTNAME = ‘DATA ACCESS 1’; WHEN ‘B01’ THEN UPDATE DEPT SET DEPTNAME = ‘DATA ACCESS 2’; ELSE UPDATE DEPT SET DEPTNAME = ‘DATA ACCESS 3’; END CASE
What is the return type of DB2?
Db2 returns the corresponding result in the THEN clause ( result_1, result_2, …) if it finds a match ( expression = expression1, expression = expression2 …). Db2 immediately stops searching once it finds a match. If Db2 does not find any match, it will return the else_result in case the ELSE clause is available.
What happens if DB2 doesn’t find any match?
If Db2 does not find any match, it will return the else_result in case the ELSE clause is available. If you don’t specify the ELSE clause, the simple CASE expression will return NULL when it finds no match. The following example returns the book title, the number of authors of each book, and a note: