How to add Foreign key in a table after the creation of the table?

5 Answers   Satyam,

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what is a constraint? Tell me about its various levels. : Sql dba

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How to set up sql*plus output format in oracle?

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SELECT emp_num, years, SUM(salary) FROM sales UNION ALL SELECT emp_id, SUM(takehomepay) FROM marketing What error is present in the sample code above? 1. Queries being combined with the UNION ALL statement are not allowed to have SELECT lists with a different number of expressions. 2. You are not allowed to use aggregate functions within two queries joined by a UNION ALL statement. 3. The UNION ALL statement incorrectly combines the "years" result from the first query with the "SUM (takehomepay)" result from the second query. 4. Unless the UNION ALL statement is replaced with a UNION statement, the queries will return duplicates. 5. The "emp_id" column from the second query must be renamed (or aliased) as "emp_num" so that it corresponds to the column name from the first query. Otherwise, the queries will not execute.

3 Answers  

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What is procedure and function?

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Which is better varchar or nvarchar?

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What is data manipulation language?

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How do I tune a sql query?

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how many ways we can we find the current date using mysql? : Sql dba

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What is difference between function and trigger?

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What is sql query optimization?

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Hi, Can anybody please explain me the flow of the below query. I am not able to understand how this query works. This query is for finding the Nth highest salary.. SELECT DISTINCT (a.sal) FROM EMP A WHERE &N = (SELECT COUNT (DISTINCT (b.sal)) FROM EMP B WHERE a.sal<=b.sal); If N = 2 then second highest salary will be the o/p. If N = 3 then third highest salary will be the o/p. and so on.. Thanks, Nitin

5 Answers   Deloitte, Ness Technologies,

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