To explain this behaviour, we need to understand how Oracle processes ROWNUM. When assigning ROWNUM to a row, Oracle starts at 1 and only increments the value when a row is selected; that is, when all conditions in the WHERE clause are met. Since our condition requires that ROWNUM is greater than 2, no rows … Read more
You can definitely get Boolean value from a SELECT query, you just can’t use a Boolean data-type. You can represent a Boolean with 1/0. CASE WHEN (10 > 0) THEN 1 ELSE 0 END (It can be used in SELECT QUERY) SELECT CASE WHEN (10 > 0) THEN 1 ELSE 0 END AS MY_BOOLEAN_COLUMN FROM … Read more
— Oracle 10g — SELECT deptno, WM_CONCAT(ename) AS employees FROM scott.emp GROUP BY deptno; Output: 10 CLARK,MILLER,KING 20 SMITH,FORD,ADAMS,SCOTT,JONES 30 ALLEN,JAMES,TURNER,BLAKE,MARTIN,WARD
What is “it” in the statement “it just says the procedure is completed”? By default, most tools do not configure a buffer for dbms_output to write to and do not attempt to read from that buffer after code executes. Most tools, on the other hand, have the ability to do so. In SQL*Plus, you’d need … Read more
This question is pretty much the inverse of Convert Unixtime to Datetime SQL (Oracle) As Justin Cave says: There are no built-in functions. But it’s relatively easy to write one. Since a Unix timestamp is the number of seconds since January 1, 1970 As subtracting one date from another date results in the number of … Read more
If your 200+ packages work as intended with “old fashioned” syntax, let it be. SQL will not start to perform better after migration to ANSI syntax – it’s just different syntax. All that being said, ANSI syntax is cleaner – you are not going to normal join if you forget (+) in some multi-column outer … Read more
This is because Oracle internally changes empty string to NULL values. Oracle simply won’t let insert an empty string. On the other hand, SQL Server would let you do what you are trying to achieve. There are 2 workarounds here: Use another column that states whether the ‘description’ field is valid or not Use some … Read more
CURRENT_DATE and CURRENT_TIMESTAMP return the current date and time in the session time zone. SYSDATE and SYSTIMESTAMP return the system date and time – that is, of the system on which the database resides. If your client session isn’t in the same timezone as the server the database is on (or says it isn’t anyway, … Read more
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(…), StandardCharsets.UTF_8)); out.write(‘\ufeff’); out.write(…); This correctly writes out 0xEF 0xBB 0xBF to the file, which is the UTF-8 representation of the BOM.
The reason for this error is that SQL SELECT statements are logically * processed in the following order: FROM: selection of one table or many JOINed ones and all rows combinations that match the ON conditions. WHERE: conditions are evaluated and rows that do not match are removed. GROUP BY: rows are grouped (and every … Read more