SELECT * FROM (SELECT ? FROM DUAL) fails

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Boris Granveaud

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Nov 17, 2016, 11:41:32 AM11/17/16
to H2 Database
Hello,

I have a problem with the following statement:

SELECT * FROM (SELECT ? FROM DUAL)

it gives this error with H2 1.4.191:

org.h2.jdbc.JdbcSQLException: Unknown data type: """?1"""; SQL statement:
SELECT * FROM (SELECT ? FROM DUAL) [50004-192]
at org.h2.message.DbException.getJdbcSQLException(DbException.java:345)
at org.h2.message.DbException.get(DbException.java:179)
at org.h2.message.DbException.get(DbException.java:155)
at org.h2.table.Table.setColumns(Table.java:425)
at org.h2.table.TableView.initColumnsAndTables(TableView.java:220)
at org.h2.table.TableView.init(TableView.java:98)
at org.h2.table.TableView.<init>(TableView.java:65)
at org.h2.table.TableView.createTempView(TableView.java:535)
at org.h2.command.Parser.readTableFilter(Parser.java:1168)

Code to reproduce:

PreparedStatement st = cnx.prepareStatement("SELECT * FROM (SELECT ? FROM DUAL)");
st.setTimestamp(1, new Timestamp(System.currentTimeMillis()));
rs = st.executeQuery();
rs.next();
System.out.println(rs.getObject(1));
rs.close();
st.close();

"SELECT ? FROM DUAL" works fine.

The problems is that the type of the parameter cannot be known when the statement is prepared so I'm not sure how the parser should deal with that.

Boris.

Thomas Mueller Graf

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Nov 29, 2016, 1:47:26 AM11/29/16
to h2-da...@googlegroups.com
Hi,

You could use "cast":

SELECT * FROM (SELECT CAST(? AS VARCHAR) FROM DUAL)
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