What is the best approach using JDBC for parameterizing an IN clause? [duplicate]

Say that I have a query of the form

SELECT * FROM MYTABLE WHERE MYCOL in (?)

And I want to parameterize the arguments to in.

Is there a straightforward way to do this in Java with JDBC, in a way that could work on multiple databases without modifying the SQL itself?

The closest question I've found had to do with C#, I'm wondering if there is something different for Java/JDBC.

There's indeed no straightforward way to do this in JDBC. Some JDBC drivers seem to support PreparedStatement#setArray() on the IN clause. I am only not sure which ones that are.

You could just use a helper method with String#join() and Collections#nCopies() to generate the placeholders for IN clause and another helper method to set all the values in a loop with PreparedStatement#setObject().

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]);
    }
}

Here's how you could use it:

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<Entity>();
    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;
}

private static Entity map(ResultSet resultSet) throws SQLException {
    Enitity entity = new Entity();
    entity.setId(resultSet.getLong("id"));
    entity.setName(resultSet.getString("name"));
    entity.setValue(resultSet.getInt("value"));
    return entity;
}

Note that some databases have a limit of allowable amount of values in the IN clause. Oracle for example has this limit on 1000 items.

Since nobody answer the case for a large IN clause (more than 100) I'll throw my solution to this problem which works nicely for JDBC. In short I replace the IN with a INNER JOIN on a tmp table.

What I do is make what I call a batch ids table and depending on the RDBMS I may make that a tmp table or in memory table.

The table has two columns. One column with the id from the IN Clause and another column with a batch id that I generate on the fly.

SELECT * FROM MYTABLE M INNER JOIN IDTABLE T ON T.MYCOL = M.MYCOL WHERE T.BATCH = ?

Before you select you shove your ids into the table with a given batch id. Then you just replace your original queries IN clause with a INNER JOIN matching on your ids table WHERE batch_id equals your current batch. After your done your delete the entries for you batch.

The standard way to do this is (if you are using Spring JDBC) is to use the org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate class.

Using this class, it is possible to define a List as your SQL parameter and use the NamedParameterJdbcTemplate to replace a named parameter. For example:

public List<MyObject> getDatabaseObjects(List<String> params) {
    NamedParameterJdbcTemplate jdbcTemplate = new NamedParameterJdbcTemplate(dataSource);
    String sql = "select * from my_table where my_col in (:params)";
    List<MyObject> result = jdbcTemplate.query(sql, Collections.singletonMap("params", params), myRowMapper);
    return result;
}

I solved this by constructing the SQL string with as many ? as I have values to look for.

SELECT * FROM MYTABLE WHERE MYCOL in (?,?,?,?)

First I searched for an array type I can pass into the statement, but all JDBC array types are vendor specific. So I stayed with the multiple ?.

I got the answer from docs.spring(19.7.3)

The SQL standard allows for selecting rows based on an expression that includes a variable list of values. A typical example would be select * from T_ACTOR where id in (1, 2, 3). This variable list is not directly supported for prepared statements by the JDBC standard; you cannot declare a variable number of placeholders. You need a number of variations with the desired number of placeholders prepared, or you need to generate the SQL string dynamically once you know how many placeholders are required. The named parameter support provided in the NamedParameterJdbcTemplate and JdbcTemplate takes the latter approach. Pass in the values as a java.util.List of primitive objects. This list will be used to insert the required placeholders and pass in the values during the statement execution.

Hope this can help you.