what are the advantages of primary key over unique+notnull

7 Answers   Consultancy, LGS, Oracle,

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I have a small PL/SQL Block assume in this way begin select * from emp where empno=100; exception when others then <Some Messages> when no_data_found then <Some Messages> when too_many_rows then <Some Messages> end; The question which he asked was whether this block will get executed normally or it will throw error ? If errored out then what is the reason for the error ? Could anybody please help me ? Regards Nakul Venkataraman

3 Answers   Satyam,

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Table 1: col1 Timestamp ---------------- 01-mar-2012 11:12:46 Table 2: col2 Timestamp -------------------- 01-mar-2012 11:12:10 01-mar-2012 11:11:23 Write a query to display a row with table2 col2 value less than tabl1 col1 value. Maximum timestamp value previous to table1 col1 value. Display a result as: Col1 col2 ----- ----- 01-mar-2012 11:12:46 01-mar-2012 11:12:10

0 Answers  

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If an unique key constraint on DATE column is created, will it validate the rows that are inserted with SYSDATE?

4 Answers  

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What is the difference between a primary key and a unique key?

0 Answers  

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What is the difference between the repeatable read and serializable isolation levels? : Transact sql

0 Answers  

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Sql technical questions

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What are the types of keys?

0 Answers  

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display null value rows with out using null function?

8 Answers   Infosys,

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How would you go about increasing the buffer cache hit ratio? 0. Explain the difference between a hot backup and a cold backup and the benefits associated with each 1. You have just had to restore from backup and do not have any control files. How would you go about bringing up this database? 2. How do you switch from an init.ora file to a spfile? 3. Explain the difference between a data block, an extent and a segment. 4. Give two examples of how you might determine the structure of the table DEPT. 5. Where would you look for errors from the database engine? 6. Compare and contrast TRUNCATE and DELETE for a table. 7. Give the reasoning behind using an index. 8. Give the two types of tables involved in producing a star schema and the type of data they hold. 9. What type of index should you use on a fact table? 10. Give two examples of referential integrity constraints. 11. A table is classified as a parent table and you want to drop and re-create it. How would you do this without affecting the children tables? 12. Explain the difference between ARCHIVELOG mode and NOARCHIVELOG mode and the benefits and disadvantages to each. 13. What command would you use to create a backup control file? 14. Give the stages of instance startup to a usable state where normal users may access it. 15. What column differentiates the V$ views to the GV$ views and how? 16. How would you go about generating an EXPLAIN plan?

2 Answers  

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how to Update table Sales_summary with max(sales) data from table sales_dataTable 1. sales_data table Table 2. Sales_summary Region sales Region sales N 500 N 0 N 800 W 0 N 600 W 899 W 458 W 900 I want the Sales_summary After Update like this Region Sales N 800 W 900

8 Answers  

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What is an inconsistent dependency?

0 Answers  

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