How to Handle NULL Values in a Constrained Integer Column using JDBC?

Setting Null Values to an Integer Column in JDBC

Question:

How can you set and get null values in a nullable Integer column with a constraint using JDBC?

Background:

Consider a table with a column named PROTOCOL, which is nullable and has a constraint that limits its values to 1, 2, or 3. When attempting to set or get null values for this column, you may encounter issues with setInt and getInt.

Solution:

To set a null value to an Integer column using JDBC, use the setNull method of the PreparedStatement class. The syntax is as follows:

pst.setNull(4, java.sql.Types.INTEGER);

Here, pst is an instance of the PreparedStatement class. The first argument, 4, represents the index of the column you want to set to null. The second argument, java.sql.Types.INTEGER, specifies the SQL type of the column.

Java 8 Update:

In Java 8, the Types class has been moved to the java.sql package, so the updated syntax for setting a null value is:

pst.setNull(4, java.sql.Types.INTEGER);

Getting Null Values:

To retrieve a null value from an Integer column using JDBC, you can use the isNull method of the ResultSet class. The syntax is:

if (rs.isNull("PROTOCOL")) {
    // Handle null value
}

Here, rs is an instance of the ResultSet class, and "PROTOCOL" is the name of the column you want to check.

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