Question

This prepared statement seems like valid SQL to me.

PreparedStatement dropTable = cnx.prepareStatement(
    "DROP TABLE IF EXISTS ?");
dropTable.setString(1, "features");
dropTable.execute();

But when I run this, I get the error:

Exception in thread “main”
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an
error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near ”features” at
line 1 at
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) at
com.mysql.jdbc.Util.getInstance(Util.java:381) at
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1031) at
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956) at
com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3558) at
com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3490) at
com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1959) at
com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2109) at
com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2648) at
com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2077)
at
com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1356)
at doriangray.db.TestSetup.main(TestSetup.java:62)

Does anyone see the problem here? I’m stumped.

Answer 1

MySQL doesn’t support prepared statements with variable table names, so you have to do this the old fashioned way, by generating SQL:

PreparedStatement dropTable = cnx.prepareStatement(
String.format("DROP TABLE IF EXISTS %s", "features"));
dropTable.execute();

In this case you might as well use regular statements since you don’t gain anything by using prepared statements.