How to Parameterize an IN Clause in Java JDBC?

JDBC Parameterization in an IN Clause

In Java JDBC, parameterizing the arguments in an IN clause requires a bit more ingenuity compared to other programming languages.

The issue arises when we need to execute a query like:

SELECT * FROM MYTABLE WHERE MYCOL IN (?)

Challenges

JDBC doesn't provide a straightforward way to parameterize the IN clause. Some JDBC drivers may support using PreparedStatement#setArray(), but this support varies across databases.

Solution

To overcome this challenge, we can use helper methods to construct placeholder strings and set the parameter values in a loop.

<code class="java">public static String preparePlaceHolders(int length) {
    return String.join(",", Collections.nCopies(length, "?"));
}

public static void setValues(PreparedStatement preparedStatement, Object... values) throws SQLException {
    for (int i = 0; i < values.length; i++) {
        preparedStatement.setObject(i + 1, values[i]);
    }
}

Usage

We can utilize these helper methods in our code as follows:

<code class="java">private static final String SQL_FIND = "SELECT id, name, value FROM entity WHERE id IN (%s)";

public List<Entity> find(Set<Long> ids) throws SQLException {
    List<Entity> entities = new ArrayList<>();
    String sql = String.format(SQL_FIND, preparePlaceHolders(ids.size()));

    try (
        Connection connection = dataSource.getConnection();
        PreparedStatement statement = connection.prepareStatement(sql);
    ) {
        setValues(statement, ids.toArray());
        
        try (ResultSet resultSet = statement.executeQuery()) {
            while (resultSet.next()) {
                entities.add(map(resultSet));
            }
        }
    }

    return entities;
}</code>

Limitations

Note that some databases, like Oracle, may impose a limit on the number of values allowed in an IN clause.

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