PreparedStatement IN clause alternatives?

An analysis of the various options available, and the pros and cons of each is available in Jeanne Boyarsky's Batching Select Statements in JDBC entry on JavaRanch Journal.

The suggested options are:

• Prepare SELECT my_column FROM my_table WHERE search_column = ?, execute it for each value and UNION the results client-side. Requires only one prepared statement. Slow and painful.
• Prepare SELECT my_column FROM my_table WHERE search_column IN (?,?,?) and execute it. Requires one prepared statement per size-of-IN-list. Fast and obvious.
• Prepare SELECT my_column FROM my_table WHERE search_column = ? ; SELECT my_column FROM my_table WHERE search_column = ? ; ... and execute it. [Or use UNION ALL in place of those semicolons. --ed] Requires one prepared statement per size-of-IN-list. Stupidly slow, strictly worse than WHERE search_column IN (?,?,?), so I don't know why the blogger even suggested it.
• Use a stored procedure to construct the result set.
• Prepare N different size-of-IN-list queries; say, with 2, 10, and 50 values. To search for an IN-list with 6 different values, populate the size-10 query so that it looks like SELECT my_column FROM my_table WHERE search_column IN (1,2,3,4,5,6,6,6,6,6). Any decent server will optimize out the duplicate values before running the query.

None of these options are ideal.

The best option if you are using JDBC4 and a server that supports x = ANY(y), is to use PreparedStatement.setArray as described in Boris's anwser.

There doesn't seem to be any way to make setArray work with IN-lists, though.

Sometimes SQL statements are loaded at runtime (e.g., from a properties file) but require a variable number of parameters. In such cases, first define the query:

query=SELECT * FROM table t WHERE t.column IN (?)

Next, load the query. Then determine the number of parameters prior to running it. Once the parameter count is known, run:

sql = any( sql, count );

For example:

/**
 * Converts a SQL statement containing exactly one IN clause to an IN clause
 * using multiple comma-delimited parameters.
 *
 * @param sql The SQL statement string with one IN clause.
 * @param params The number of parameters the SQL statement requires.
 * @return The SQL statement with (?) replaced with multiple parameter
 * placeholders.
 */
public static String any(String sql, final int params) {
    // Create a comma-delimited list based on the number of parameters.
    final StringBuilder sb = new StringBuilder(
        String.join(", ", Collections.nCopies(possibleValue.size(), "?")));

    // For more than 1 parameter, replace the single parameter with
    // multiple parameter placeholders.
    if (sb.length() > 1) {
        sql = sql.replace("(?)", "(" + sb + ")");
    }

    // Return the modified comma-delimited list of parameters.
    return sql;
}

For certain databases where passing an array via the JDBC 4 specification is unsupported, this method can facilitate transforming the slow = ? into the faster IN (?) clause condition, which can then be expanded by calling the any method.

No simple way AFAIK. If the target is to keep statement cache ratio high (i.e to not create a statement per every parameter count), you may do the following:

1. create a statement with a few (e.g. 10) parameters:

   ... WHERE A IN (?,?,?,?,?,?,?,?,?,?) ...

2. Bind all actuall parameters

   setString(1,"foo"); setString(2,"bar");

3. Bind the rest as NULL

   setNull(3,Types.VARCHAR) ... setNull(10,Types.VARCHAR)

NULL never matches anything, so it gets optimized out by the SQL plan builder.

The logic is easy to automate when you pass a List into a DAO function:

while( i < param.size() ) {
  ps.setString(i+1,param.get(i));
  i++;
}

while( i < MAX_PARAMS ) {
  ps.setNull(i+1,Types.VARCHAR);
  i++;
}

You can use Collections.nCopies to generate a collection of placeholders and join them using String.join:

List<String> params = getParams();
String placeHolders = String.join(",", Collections.nCopies(params.size(), "?"));
String sql = "select * from your_table where some_column in (" + placeHolders + ")";
try (   Connection connection = getConnection();
        PreparedStatement ps = connection.prepareStatement(sql)) {
    int i = 1;
    for (String param : params) {
        ps.setString(i++, param);
    }
    /*
     * Execute query/do stuff
     */
}

An unpleasant work-around, but certainly feasible is to use a nested query. Create a temporary table MYVALUES with a column in it. Insert your list of values into the MYVALUES table. Then execute

select my_column from my_table where search_column in ( SELECT value FROM MYVALUES )

Ugly, but a viable alternative if your list of values is very large.

This technique has the added advantage of potentially better query plans from the optimizer (check a page for multiple values, tablescan only once instead once per value, etc) may save on overhead if your database doesn't cache prepared statements. Your "INSERTS" would need to be done in batch and the MYVALUES table may need to be tweaked to have minimal locking or other high-overhead protections.

I've never tried it, but would .setArray() do what you're looking for?

Update: Evidently not. setArray only seems to work with a java.sql.Array that comes from an ARRAY column that you've retrieved from a previous query, or a subquery with an ARRAY column.

I suppose you could (using basic string manipulation) generate the query string in the PreparedStatement to have a number of ?'s matching the number of items in your list.

Of course if you're doing that you're just a step away from generating a giant chained OR in your query, but without having the right number of ? in the query string, I don't see how else you can work around this.

try using the instr function?

select my_column from my_table where  instr(?, ','||search_column||',') > 0

then

ps.setString(1, ",A,B,C,"); 

Admittedly this is a bit of a dirty hack, but it does reduce the opportunities for sql injection. Works in oracle anyway.

Generate the query string in the PreparedStatement to have a number of ?'s matching the number of items in your list. Here's an example:

public void myQuery(List<String> items, int other) {
  ...
  String q4in = generateQsForIn(items.size());
  String sql = "select * from stuff where foo in ( " + q4in + " ) and bar = ?";
  PreparedStatement ps = connection.prepareStatement(sql);
  int i = 1;
  for (String item : items) {
    ps.setString(i++, item);
  }
  ps.setInt(i++, other);
  ResultSet rs = ps.executeQuery();
  ...
}

private String generateQsForIn(int numQs) {
    String items = "";
    for (int i = 0; i < numQs; i++) {
        if (i != 0) items += ", ";
        items += "?";
    }
    return items;
}

I just worked out a PostgreSQL-specific option for this. It's a bit of a hack, and comes with its own pros and cons and limitations, but it seems to work and isn't limited to a specific development language, platform, or PG driver.

The trick of course is to find a way to pass an arbitrary length collection of values as a single parameter, and have the db recognize it as multiple values. The solution I have working is to construct a delimited string from the values in the collection, pass that string as a single parameter, and use string_to_array() with the requisite casting for PostgreSQL to properly make use of it.

So if you want to search for "foo", "blah", and "abc", you might concatenate them together into a single string as: 'foo,blah,abc'. Here's the straight SQL:

select column from table
where search_column = any (string_to_array('foo,blah,abc', ',')::text[]);

You would obviously change the explicit cast to whatever you wanted your resulting value array to be -- int, text, uuid, etc. And because the function is taking a single string value (or two I suppose, if you want to customize the delimiter as well), you can pass it as a parameter in a prepared statement:

select column from table
where search_column = any (string_to_array($1, ',')::text[]);

This is even flexible enough to support things like LIKE comparisons:

select column from table
where search_column like any (string_to_array('foo%,blah%,abc%', ',')::text[]);

Again, no question it's a hack, but it works and allows you to still use pre-compiled prepared statements that take *ahem* discrete parameters, with the accompanying security and (maybe) performance benefits. Is it advisable and actually performant? Naturally, it depends, as you've got string parsing and possibly casting going on before your query even runs. If you're expecting to send three, five, a few dozen values, sure, it's probably fine. A few thousand? Yeah, maybe not so much. YMMV, limitations and exclusions apply, no warranty express or implied.

But it works.

No one else seems to have suggested using an off-the-shelf query builder yet, like jOOQ or QueryDSL or even Criteria Query that manage dynamic IN lists out of the box, possibly including the management of all edge cases that may arise, such as:

• Running into Oracle's maximum of 1000 elements per IN list (irrespective of the number of bind values)
• Running into any driver's maximum number of bind values, which I've documented in this answer
• Running into cursor cache contention problems because too many distinct SQL strings are "hard parsed" and execution plans cannot be cached anymore (jOOQ and since recently also Hibernate work around this by offering IN list padding)

(Disclaimer: I work for the company behind jOOQ)

Just for completeness: So long as the set of values is not too large, you could also simply string-construct a statement like

... WHERE tab.col = ? OR tab.col = ? OR tab.col = ?

which you could then pass to prepare(), and then use setXXX() in a loop to set all the values. This looks yucky, but many "big" commercial systems routinely do this kind of thing until they hit DB-specific limits, such as 32 KB (I think it is) for statements in Oracle.

Of course you need to ensure that the set will never be unreasonably large, or do error trapping in the event that it is.

Following Adam's idea. Make your prepared statement sort of select my_column from my_table where search_column in (#) Create a String x and fill it with a number of "?,?,?" depending on your list of values Then just change the # in the query for your new String x an populate

OK, so I couldn't remember exactly how (or where) I did this before so I came to stack overflow to quickly find the answer. I was surprised I couldn't.

So, how I got around the IN problem a long time ago was with a statement like this:

where myColumn in ( select regexp_substr(:myList,'[^,]+', 1, level) from dual connect by regexp_substr(:myList, '[^,]+', 1, level) is not null)

set the myList parameter as a comma delimited string: A,B,C,D...

Note: You have to set the parameter twice!

This worked for me (psuedocode):

public class SqlHelper
{
    public static final ArrayList<String>platformList = new ArrayList<>(Arrays.asList("iOS","Android","Windows","Mac"));

    public static final String testQuery = "select * from devices where platform_nm in (:PLATFORM_NAME)";
}

specicify binding :

public class Test extends NamedParameterJdbcDaoSupport
public List<SampleModelClass> runQuery()
{
    //define rowMapper to insert in object of SampleClass
    final Map<String,Object> map = new HashMap<>();
    map.put("PLATFORM_LIST",DeviceDataSyncQueryConstants.platformList);
    return getNamedParameterJdbcTemplate().query(SqlHelper.testQuery, map, rowMapper)
}