Java MySql preparedStatement

Question

Hey I have problem with preparedStatement, I want to find min for few columns, I'm iterating over the names of columns and inserting them inside my preparedStatement like that

connection.prepareStatement("SELECT min( ? ) as min FROM test");
minStatement.setString(1, "some_column");

and when retrieving from ResultSet I'm getting the column name, in this case the result is "some_column" and should be 0. When using normal statement it does return right value. I have no idea what I'm doing wrong. Thanks for any help.

The idea behind a prepared statement is that the DB only compiles and optimizes the query once. It can't do this if the location is going to be changing every time the query is used — Floegipoky
– Floegipoky, Commented Nov 14, 2013 at 23:49

Przemyslaw Kruglej · Accepted Answer · 2013-11-14 23:02:30Z

4

You cannot specify a column name in prepared statement like this, what you get is:

SELECT MIN('some_column') AS min FROM test

Instead of:

SELECT MIN(some_column) AS min FROM test

So, your query selects the minimal value 'some_column'... which is 'some_column'.

You could, instead, try that:

connection.prepareStatement("SELECT min(" + some_column + " ) as min FROM test");

But this may lead to injection attacks.

answered Nov 14, 2013 at 23:02

Przemyslaw Kruglej

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1 Comment

user2141889 Over a year ago

I was close with my thinking, thank you for answer, in my case injections are not the problem:)

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