diff bet. select * and select column name in sql query

Question

1.00/5 (2 votes)

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Hello,

I came across through below interesting question? What is the difference between:

SQL

select * from employee

and

SQL

select empid,empname,empcity,empsalary from employee

Thanks.

Posted 4-Sep-14 16:51pm

kk2014

Updated 4-Sep-14 17:36pm

Wendelius

v2

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Comments

Sergey Alexandrovich Kryukov 5-Sep-14 1:41am

Incorrect question. The difference is: "first query has * in it". Or: "first query searches in all columns". Or "first query has two words". Which answer would you prefer? Questions about "difference" are most usually incorrect.
And why not simply reading elementary SQL textbook or reference?
—SA

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Wendelius · Accepted Answer · 2014-09-04T17:35:00

Solution 1

This sounds a bit like a homework....

Anyhow, there are quite a few differences. To name some from the top of my head:
<lu>

the amount of columns is different

the order of the same columns returned may be different

the second one may fail because of wrongly typed column name

the second one may fail because of mixed case characters column names

the second one may use (different) index

the second may return the results without ever accessing the employee table at all

The amount of data transferred to the client may be different

As said this sounds a bit like homework, so at the moment I'll leave the justifications out from this answer :)

Posted 4-Sep-14 17:35pm

Wendelius

Updated 4-Sep-14 18:56pm

v2

Comments

CPallini 5-Sep-14 1:34am

5.

Wendelius 5-Sep-14 4:39am

Thanks :)

Sergey Alexandrovich Kryukov 5-Sep-14 1:43am

I limited my response by a note that the "difference" question is incorrect. Indeed, what is "difference".
My 5 for spotting so many aspects. :-)
—SA

Wendelius 5-Sep-14 4:39am

Thanks :)

kk2014 5-Sep-14 2:38am

Hi Mika Wendelius,

the differences u said are the basic differences which I know. are there any other differences?

Thanks,

thatraja 5-Sep-14 3:41am

His answer is more than enough. For your question, his first & last points are important. If you want to select only one column's value, you should not use SELECT * query when your table has 100s of columns. That's unnecessary. Low performance.

Wendelius 5-Sep-14 4:38am

If you don't define the context more accurately I think it's quite hard for anybody to answer the question.

thatraja 5-Sep-14 3:37am

5!

Wendelius 5-Sep-14 4:39am

Thanks :)

Gihan Liyanage · Accepted Answer · 2014-09-04T18:26:00

Solution 2

Say google first.. When you have an issue or doubt

Your solution is here.

Select * Vs Select Column Name[^]

Posted 4-Sep-14 18:26pm

Gihan Liyanage

Comments

CPallini 5-Sep-14 1:34am

5.

thatraja 5-Sep-14 3:37am

5!

diff bet. select * and select column name in sql query

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