Using IN Keyword. Help!

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Hi!

I'm a newbie to MS SQL! I have a doubt regarding IN Keyword.

Please explain the difference in these queries

With IN Keyword

SQL

SELECt * FROM Products
WHERE UnitPrice IN (SELECT UnitPrice FROM Products Where UnitPrice >10)

Without IN Keyword

SQL

SELECt * FROM Products
WHERE UnitPrice = (SELECT UnitPrice FROM Products Where UnitPrice >10)

Thanks in advance!

Posted 16-Jan-13 22:04pm

Newbie271

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OriginalGriff · Accepted Answer · 2013-01-16T22:20:00

Simple: The first will work, the second will fail.

That's a generalisation, but it's also true. The second will fail the moment there is more than one Product where the UnitPrice is greater than 10, because the subquery

SQL

SELECT UnitPrice FROM Products Where UnitPrice >10

will return more than one value, and the equality test cannot cope with that.

The IN clause says "matches any of these values" so it will work with one or more Products where the UnitPrice is greater than 10.

josh-jw · Accepted Answer · 2013-01-16T22:22:00

here

SQL

SELECt * FROM Products
WHERE UnitPrice = (SELECT UnitPrice FROM Products Where UnitPrice >10)

SELECT UnitPrice FROM Products Where UnitPrice >10 if this query return more than one value error will throw. that means you can assign more than one value to Unitprice
.but if you use in operator i it will check the unit price selected and will get appropriate one.
like

SQL

SELECt * FROM Products
WHERE UnitPrice IN (10,11,12,13)

// willnot throw error

XML

<pre lang="sql">SELECt * FROM Products
WHERE UnitPrice =(10,11,12,13)</pre>

//throw error

Abhinav S · Accepted Answer · 2013-01-16T22:17:00

Solution 1

IN vs. JOIN vs. EXISTS[^] is an article that should help you understand the difference between these two queries in terms of performance and other factors.

Posted 16-Jan-13 22:17pm

Abhinav S

Comments

OriginalGriff 17-Jan-13 4:21am

It's a bit more fundamental than that, Abhinav - what happens if there are two products with a unit price of 11? :laugh:

Abhinav S 17-Jan-13 4:25am

Ah the classic subquery returned multiple records error.

Using IN Keyword. Help!

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