Re: Jaw drop: JDBC will let you update rows with the wrong data type (within reason)

Do you use JPA? Just asking as eclipselink or hibernate will manage all
this for you and you never have to write jdbc type code or sql again.

On Wed, 6 Oct 2021, 20:58 David Gibbs via JAVA400-L, <
java400-l@xxxxxxxxxxxxxxxxxx> wrote:

Folks:

I just encountered a situation where JDBC allowed me to update rows in a
table where the values did not match the column definition.

As long as you use the setObject method, you can set a numeric column to
a string value and a character column with a numeric value.

The value contents have to match the column definition, but it doesn't
seem to care what the data type being passed in.

For instance:

You create a table as such ...

create table testtab1 (
decfield decimal(8,0),
charfield char(10)
)

... and then run code like this ...

try (
Connection conn = DriverManager.getConnection(url, props);
PreparedStatement stmt = conn.prepareStatement("insert into
dxglib/testtab1 (decfield,charfield) values(?,?)");
) {

stmt.setObject(1, 1);
stmt.setObject(2, "xyz");
stmt.executeUpdate();

stmt.setObject(1, "2");
stmt.setObject(2, 3);
stmt.executeUpdate();

stmt.setObject(1, "A");
stmt.setObject(2, 3);
stmt.executeUpdate();

} catch (Exception e) {
e.printStackTrace();
}

.. the first two updates will work fine, but the 3rd will fail.

david
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