103. Examine the structure of the TRANSACTIONS table:
name Null Type
TRANS_ID NOT NULL NUMBER(3)
CUST_NAME VARCHAR2(30)
TRANS_DATE DATE
TRANS_AMT NUMBER(10,2)
You want to display the transaction date and specify whether it is a weekday or weekend.
Evaluate the following two queries:
SQL>SELECT TRANS_DATE,CASE
WHEN TRIM(TO_CHAR(trans_date,'DAY')) IN ('SATURDAY','SUNDAY') THEN 'weekend'
ELSE 'weekday'
END "Day Type"
FROM transactions;
SQL>SELECT TRANS_DATE, CASE
WHEN TO_CHAR(trans_date,'DAY') BETWEEN 'MONDAY' AND 'FRIDAY' THEN 'weekday'
ELSE 'weekend'
END "Day Type"FROM transactions;
Which statement is true regarding the above queries?
A. Both give wrong results.
B. Both give the correct result.
C. Only the first query gives the correct result.
D. Only the second query gives the correct result.
SQL>SELECT HIREDATE,CASE
WHEN TRIM(TO_CHAR(HIREDATE,'DAY')) IN ('SATURDAY','SUNDAY') THEN 'weekend' ELSE 'weekday' END "Day Type"
FROM emp;
实验验证，此处使用scott的emp表下的HIREDATE字段来做测试
scott@TEST0924> SELECT HIREDATE,CASE
2 WHEN TRIM(TO_CHAR(HIREDATE,'DAY')) IN ('SATURDAY','SUNDAY') THEN 'weekend' ELSE 'weekday' END "Day Type"
3 FROM emp;
HIREDATE Day Typ
------------------ -------
17-DEC-80 weekday
20-FEB-81 weekday
22-FEB-81 weekend
02-APR-81 weekday
28-SEP-81 weekday
01-MAY-81 weekday
09-JUN-81 weekday
19-APR-87 weekend
17-NOV-81 weekday
08-SEP-81 weekday
23-MAY-87 weekend
03-DEC-81 weekday
03-DEC-81 weekday
23-JAN-82 weekend
14 rows selected.
scott@TEST0924> SELECT HIREDATE, CASE
2 WHEN TO_CHAR(HIREDATE,'DAY') BETWEEN 'MONDAY' AND 'FRIDAY' THEN 'weekday' ELSE 'weekend'
3 END "Day Type"FROM emp;
HIREDATE Day Typ
------------------ -------
17-DEC-80 weekend
20-FEB-81 weekend
22-FEB-81 weekend
02-APR-81 weekend
28-SEP-81 weekend
01-MAY-81 weekend
09-JUN-81 weekend
19-APR-87 weekend
17-NOV-81 weekend
08-SEP-81 weekend
23-MAY-87 weekend
03-DEC-81 weekend
03-DEC-81 weekend
23-JAN-82 weekend
14 rows selected.