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Select 1 from dualunionselect 'A' from dual; I guess the query will select zero rows. Is it wrong or right ? if wrong thenWhat will be the result set for the query?Thanks in advance.
nis1981
- Aug 3rd, 2008
Inorder to use UNION SET OPERATOR the datatype and the number of columns should match. Here you are trying to get the union of a character datatype and a number, hence you get an error.
Renuka Rajput
- Jul 29th, 2006
i would like to add one more point that not only datatypes but also structure of both the select statement should be same.if we write query asselect 1,2 from dualunionselect 1 from dualit will still results in error and the error isexpression must have same datatype as corresponding expression
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What is the difference between single quote (') and double quote(") in relates to using in SQL. When do you use 'xxx' and "xxx"? what is the difference both of them?
g_sidhu
- Feb 7th, 2008
Date and character literals must be enclosed within single quotation marks (' ');If a column alias contains a space, it should be enclosed in double quotation marks.
rampratap409
- Dec 4th, 2006
double quote(") is used to give user defined column alias example:select empno , ename "employee name" from emp;this will print column heading as: EMPNO ...
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1. why the performance of the table is degraded when more index is created on the table......2. whats the main usage of synonym other than that of creating other names to objects....3. shall we able to create an primary index on the table which already has the null value? if yes syntax please.........4. whats the main usage of trigger.......... (eg..) please...
shravanam
- Oct 28th, 2007
1. When you create more indexes on a table , for example table A has 10 columns and you have create 8 indexes on that table. Then whenever you r going to retrieve data from that table each row o...
Sushma
- Jul 11th, 2007
3.If we have the null values in the column then we can not create primary key trigger on that column.4. It is an event that raised implicitly when you update the table.Regards,Sushma
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How to get single entry of empname from emp table for employee taking max salary
sampra
- Mar 6th, 2012
Select salry from Hello h where 1=(select count (distinct salry) from hello where h.salry
maqsood
- Jul 10th, 2006
Select last_name from employeesWhere rownum
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What is Query Analyser?
Sundaresan
- Aug 29th, 2006
Grid computing
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What is select statement to spell out SALARY?(Query should work upto 5 million)
krishnaindia2007
- Jun 22nd, 2008
SELECT TO_CHAR(TO_DATE(11111,'J'),'JSP')||' DOLLARS' FROM DUALThis will work for the values in between 1 and 5373484 only.
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May i know about ref cursor?.
krishnaindia2007
- Jun 22nd, 2008
Ref cursor is basically a data type. A variable declared based on that data type is called cursor variable. The main advantage of using this variable is we can dynamically assosiate with different queries at runtime depending upon our requirement.
tariq_oracle
- Jun 8th, 2008
1. This is a dynamic cursor which can holds multiple value at run time2. Actually this is nothing but a data type of cursor variable
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What are cursor attributes?
%ROWCOUNT%NOTFOUND%FOUND%ISOPEN
narmadac
- Feb 11th, 2010
Cursor attributes when appended to the cursor name allow the users to access useful information from the retrieved rows. After opening a cursor a 'fetch' statement is used to fetch rows from the...
syam sundar
- Aug 17th, 2007
%ROWTYPE - returns number of the rows which are fetched/updated/deleted%ISOPEN - returns true if the cursor is open%FOUND - returns true if the cursor fetched any row%NOTFOUND-returns true if the cursor does not fetch any row
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What is the data type of the column of Dual table?
g_sidhu
- Feb 13th, 2008
The DUAL table is owned by the user SYS and can be accessed by all users. It contains one column, DUMMY, and one row with the value X. The DUAL table is useful when you want to return a value once onl...
kowmudiswarna
- Sep 13th, 2007
Hi,The data type of column of dual table is character data type i.e varchar2
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How to compare the total salary of all employee with a individual employee salary for a particular department.
sumanta.bala
- Jun 5th, 2009
SELECT ename,deptno,sal,TRUNC (AVG (sal) OVER (PARTITION BY deptno)) avg_sal FROM scott.emp
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There is a table with Pluks(‘plk’) and Zinks (‘zin’). Each Pluk onlyresides on a single Zink and each Zink may contain multiple Pluks. Howdo you find how many Pluks are on each and every Zink? Please provide SQL.
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How to get 1,4,7,10.....rows from a table
Arjunya
- Apr 29th, 2010
SELECT XFROM YWHERE MOD(X,3) = 1;Where X is the column name and Y is the table name.
ganne
- Aug 2nd, 2006
Select rownum,empno from emp group by rownum,empno having mod(rownum,3)=1;
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Explain psudo column Label with an example
g_sidhu
- Feb 7th, 2008
LEVELYou use LEVEL with the SELECT CONNECT BY statement to organize rows from a database table into a tree structure. LEVEL returns the level number of a node in a tree structure. The root is level 1, children of the root are level 2, grandchildren are level 3, and so on.
Tatyana
- May 5th, 2006
Sorry, sorry, I am wrong. Rowid is a pseudocolumn.
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Explain what is mutation and what is mutating table and how this mutation problem is solved in a table
Nicsmart
- Mar 31st, 2010
A mutating table is a table that is currently being modified by an INSERT,UPDATE,DELETE statement or a table that might need to be updated by the effects of a declarative DELETE CASCADE referential in...
Nasim
- Aug 24th, 2007
One solution also exist:create a row level trigger and insert/update the data and take it in collections( varray or nested table or associative array). Then write a after statement level trigger and fetch that data.
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What is join? Types of Join & Difference between each.
sindhu
- Aug 2nd, 2007
Thanks for your answer.It helped me alot for my interview.
BinduJoseph
- Jan 22nd, 2007
First lets consider these two tables. AKey Data----------- ----------1 a 2 b BKey Data----------- ----------1 c 3 d ...
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