Oracle 051 (oracle 11g), 05111g

Oracle 051 (oracle 11g), 05111g

Oracle 051 questions (oracle 11g)

1. INTERVAL usage

Select interval '000000' MONTH, INTERVAL '54-2 'year to month, INTERVAL '11: 12: 300 'hour to second from dual;

The query result is:

INTERVAL '000000' MONTH --------------------------------------------------------------------------- INTERVAL '54-2' YEARTOMONTH --------------------------------------------------------------------------- INTERVAL '11: 12: 10.1234567 'HOURTOSECOND --------------------------------------------------------------------------- + 25-00 + 54-02 + 00 11:12:10. 123457

 

2. ORDERBY

Select distinct deptno, sal from emp order1;

Equivalent

Select distinct deptno, sal from emp orderDeptno;

 

Select distinct deptno, sal from emp order2;

Equivalent

Select distinct deptno, sal from emp orderSal;

 

3. Use data merging in the SELECT clause

The emp table is as follows:

EMPNO	ENAME	JOB	MGR	HIREDATE	SAL	COMM
7369	SMITH	CLERK	7902	17-DEC-80	800
7499	ALLEN	SALESMAN	7698	20-FEB-81	1600	300
7521	WARD	SALESMAN	7698	22-FEB-81	1250	500
7566	JONES	MANAGER	7839	02-APR-81	2975
7654	MARTIN	SALESMAN	7698	28-SEP-81	1250	1400
7698	BLAKE	MANAGER	7839	01-MAY-81	2850
7782	CLARK	MANAGER	7839	09-JUN-81	2450
7788	SCOTT	ANALYST	7566	19-APR-87	3000
7839	KING	PRESIDENT		17-NOV-81	5000

The query statement is as follows:

Select empno | ''| TO_CHAR (ROUND (SYSDATE-hiredate)/365) * sal + comm) from emp;

The query result is:

EMPNO | ''| TO_CHAR (ROUND (SYSDATE-HIREDATE)/365) * SAL + COMM) -------------------------------------------------------------------------------- 7369 7499 56300 7521 44250 7566 7654 43900 7698 7782 7788 7839 7844 51000 7876 7900 7902 7934

The query result contains only one column, indicating the concatenation of the empno value and the following arithmetic value.

Note:

A) Use "|" in SELECT to merge data

B) the query result is incorrect. No calculation result is returned for rows with the COMM value being null.

 

4. Q-quote delimiter

Query statement

Select Q' [I am 'OK "ey"]' from dual;

Output

I am 'OK "ey"

The following symbols are all feasible.

Select Q' <I am 'OK "ey">' from dual; Select Q' \ I am 'OK "ey" \' from dual; Select Q' {I am 'OK "ey"}' from dual; Select Q' # I am 'OK "ey" #' from dual; Select q '* I am' OK "ey" * 'from dual; Select Q' (I am 'OK "ey")' from dual; Select Q' % I am 'OK "ey" %' from dual;

 

5. USING

Select * from emp join dept using (deptno );

The query result is:

DEPTNO EMPNO ENAME JOB MGR HIREDATE SAL COMM DNAME LOC --------------------------------------------------------------------------------------------------------- 10 7782 clark manager 7839 09-JUN-81 2450 ACCOUNTING NEW YORK 10 7839 king president 17-NOV-81 5000 ACCOUNTING NEW YORK 10 7934 miller clerk 7782 23-JAN-82 1300 ACCOUNTING NEW YORK 20 7566 jones manager 7839 02-APR-81 2975 RESEARCH DALLAS 20 7902 ford analyst 7566 03-DEC-81 3000 RESEARCH DALLAS 20 7876 adams clerk 7788 23-MAY-87 1100 RESEARCH DALLAS 20 7369 smith clerk 7902 17-DEC-80 800 RESEARCH DALLAS 20 7788 scott analyst 7566 19-APR-87 3000 RESEARCH DALLAS 30 7521 ward salesman 7698 22-FEB-81 1250 500 SALES CHICAGO 30 7844 turner salesman 7698 08-SEP-81 1500 0 SALES CHICAGO 30 7499 allen salesman 7698 20-FEB-81 1600 300 SALES CHICAGO 30 7900 james clerk 7698 03-DEC-81 950 SALES CHICAGO 30 7698 blake manager 7839 01-MAY-81 2850 SALES CHICAGO 30 7654 martin salesman 7698 28-SEP-81 1250 1400 SALES CHICAGO

Make oracle use the fields specified by using for join, instead of the default two in the natural join connection.

Reference http://blog.163.com/wkyuyang_001/blog/static/108021228200917598857/

 

Supplement:

1. COUNT (*), COUNT (column_name), COUNT (DISTINCT)

COUNT (*)-all, include null

COUNT (column_name)-without null

COUNT (DISTINCT)-remove duplicate

 

2. SQL statement execution sequence

A) FROM (query data sources)

B) WHERE (filter rows based on the conditions in WHERE)

C) group by (Execution GROUP)

D) HAVING (filtering in each group based on the conditions in HAVING)

E) SELECT (pick out the specified column)

F) order by (SORT)

Sugeei

March 28

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