A) I have 100 columns in emp table , which of the below queries will give good performance and WHY?1) Select * from emp;2)select col1,col2,col3,..............col100 from emp;B) we have 2 tables T1(100 records) and T2(1000) recordsWhen we use the below queries , it will generate Cartesian product , which query will give better performance and WHY?1)Selct * from t1,t2 ;2)select * from t2,t1;

DSADSF

• Sep 24th, 2011

SELECT * FROM T1,T2
WHERE T1.COLUM_NAME=T2.COLUM_NAME;

NOTE THAT COLUMN NAME AND DATA SHOULD BE SAME

nandha_spartan

 Profile Answers by nandha_spartan Questions by nandha_spartan

• Aug 18th, 2011

Set time on

then

write the query then execute display output and timing..

then write set time off
write same query then execute display output ,compare both timing it is called query performance

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A script is inserting data into one table, it was taking 15 min to complete before. Today it is taking more than 2 hours. What kind of action you will take?

smonroy

 Profile Answers by smonroy Questions by smonroy

• Sep 28th, 2011

Also you can do the below steps

1.- Normalization your DB
2.- Break the INSERT in some INSERTs instead have one
3.- You need to create indexes on the table

arindam_0006in

 Profile Answers by arindam_0006in Questions by arindam_0006in

• Aug 11th, 2010

Do not paste in sql client and run the script. Use sql administration console. First analyze it and browse the sql dump file and execute it. Think there will be no issue.

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