Name: mf23781 Date: 04/30/99


This JdbcOdbc problem was found when testing with an Oracle
Level 3 ODBC driver.
.
Our AIX testing environment is
-JDK 116 Jdbc-Odbc Bridge on AIX 4.3.0.0
-ODBC Driver: evaluation release version 03.50 for AIX downloaded
 from www.merant.com
 http://www.merant.com/datadirect/download/eval/Forms/connect_odbc.htx
-Database: oracle 8.0.4 on AIX 4.3.0.0
.
The test suite that we are using is the JDBC compliant test
suite downloaded from Javasoft partner site in the private
area: jdbc.tests.src and jdbc-harness which controls the running
of the tests.
To expose the defect in :-
getProcedureColumns() use test jdbcTest.dbmetadata.GetProcedures
getTypeInfo() use test jdbcTest.dbmetadata.GetSchemas
getColumns() use test jdbcTest.dbmetadata.GetColumns
.
The underlying defect; namely that column names are incorrect
when using ODBC 3.0; shows up in several places.
.
.
The getProcedureColumns() method of the jdbc-odbc bridge implementation
of java.sql.DatabaseMetaData returns a ResultSet that has incorrect column
names (according to JDBC 1.2 spec)
.
      method |col.| Recieved | Specification
----------------------+----+----------------+---------------
getProcedureColumns() | 8 | COLUMN_SIZE | PRECISION
getProcedureColumns() | 9 | BUFFER_LENGTH | LENGTH
getProcedureColumns() | 10 | DECIMAL_DIGITS | SCALE
getProcedureColumns() | 11 | NUM_PREC_RADIX | RADIX
getTypeInf() | 3 | COLUMN_SIZE | PRECISION
getTypeInf() | 12 | AUTO_UNIQUE | AUTO_INCREMENT
getColumns() | 15 | DATETIME_CODE | SQL_DATETIME_SUB
.
With these incorrect column names, the JDBC-ODBC Bridge will
not be JDBC compliant. For applications which access the
columns using column number, the renamed columns will not
present any problems as the column nature is the same. However,
for applications which uses column name, these renamed columns
will present a problem.
.
.
Investigation:
.
The above problems are basically caused by the same problem as
detailed below.
.
Our JDBC-ODBC Bridge has been changed to support concurrency
for WebSphere. ODBC version 3 or above will be used. Therefore,
we need to add code in to support ODBC version 3 & above to
make it JDBC compliant but at the same time it needs to be
backward compatible for existing users of the Bridge especially
for NT platform. We aim to keep the NT and AIX source code to
be on the same baseline.
.
A simpler fix would be to make use of odbc 3 functions to
create column alias for these columns but this would break
existing users with ODBC version 2.
.
.
Fix:
.
Based on the above considerations, the fix we have adopted is
as follows:
.
In JdbcOdbcDatabaseMetaData.java, we need to check the ODBC
versions for 2 or above. Pseudo columns should only be added
for version 2 as in original code. The call for setSQLTypeColumn
should apply for version 2 or above. For version 3 or above
we need to add logic to rename those columns.
.
JdbcOdbcDatabaseMetaData.java
.
(getProcedureColumns)
2273d2270
< int odbcver;
2312,2318c2309
< // For ODBC version 2 or above, we need to set
< // SQL type column. For ODBC 3 or above, we
< // need to rename some columns in order to be JDBC
< // compliant
<
< odbcver = Con.getODBCVer ();
< if (odbcver >= 2) {
---
> if (Con.getODBCVer () == 2) {
2320,2326d2310
< if (odbcver >= 3) {
< rs.setAliasColumnName ("PRECISION", 8);
< rs.setAliasColumnName ("LENGTH", 9);
< rs.setAliasColumnName ("SCALE", 10);
< rs.setAliasColumnName ("RADIX", 11);
< }
<
.
(getColumns)
2562d2545
< int odbcver;
2601,2602c2584
< odbcver = Con.getODBCVer ();
< if (odbcver == 2) {
---
> if (Con.getODBCVer () == 2) {
2624,2632d2605
<
< // For ODBC version 2 or above, we need to set
< // SQL type column. For ODBC 3 or above, we
< // need to rename some columns in order to be JDBC
< // compliant
<
< } else if (odbcver >= 3) {
< rs.setSQLTypeColumn (5);
< rs.setAliasColumnName ("SQL_DATETIME_SUB", 15);
2634d2606
<
.
(getBestRowIdentifier)
2860,2864c2832
<
< // For ODBC version 2 or above, we need to set
< // SQL type column.
< // if (Con.getODBCVer () == 2) {
< if (Con.getODBCVer () >= 2) {
---
> if (Con.getODBCVer () == 2) {
.
(getVersionColumns)
2938,2942c2906
<
< // For ODBC version 2 or above, we need to set
< // SQL type column.
< // if (Con.getODBCVer () == 2) {
< if (Con.getODBCVer () >= 2) {
---
> if (Con.getODBCVer () == 2) {
.
(getTypeInfo)
3324d3287
< int odbcver;
3363,3364c3326
< odbcver = Con.getODBCVer ();
< if (odbcver == 2) {
---
> if (Con.getODBCVer () == 2) {
3380,3389d3341
<
< // For ODBC version 2 or above, we need to set
< // SQL type column. For ODBC 3 or above, we
< // need to rename some columns in order to be JDBC
< // compliant
<
< } else if (odbcver >= 3) {
< rs.setSQLTypeColumn (2);
< rs.setAliasColumnName ("PRECISION", 3);
< rs.setAliasColumnName ("AUTO_INCREMENT", 12);
3391d3342
<
.
JdbcOdbcResultSet.java
.
Logic is added to provide column alias name. setAliasColumnName and
mapColumnName are 2 new methods in class ResultSet to provide column
alias rename. Only column name is mapped to JDBC-compliant naming convention.
All other processings for the renamed columns remained the same.
.
        //--------------------------------------------------------------------
        // setAliasColumnName
        // Given a column number and column name to be used, set the
        // column alias name for the corresponding column number.
        // If the column number is out-of-range, nothing is set and
        // original column name will be used and not renamed.
        //--------------------------------------------------------------------
.
        public void setAliasColumnName (
                String AliasColumnName,
                int column)
        {
                if ((column > 0) &&
                                (column <= numberOfCols)) {
                        boundCols[column-1].setAliasName (AliasColumnName);
                }
        }
.
.
        //--------------------------------------------------------------------
        // mapColumnName
        // Given a column name, map it to the corresponding column rename in
        // the result set. If no column rename exist, return the original
        // column name. If the column number is out-of-range, return original
        // column name.
        //--------------------------------------------------------------------
        public String mapColumnName (
                String columnName,
                int column)
        {
                if ((column > 0) &&
                                (column <= numberOfCols)) {
                        return boundCols[column-1].mapAliasName (columnName);
                }
                else {
                        return columnName;
                }
        }
.
JdbcOdbcBoundCol.java
.
In JdbcOdbcBoundCol.java, 2 new protected variables are introduced: a boolean
flag isrenamed to show whether alias Name is to be used and a String to store
the alias name with 2 new methods to set and get the alias name.
.
        //--------------------------------------------------------------------
        // setAliasName
        // Sets the column name to be used
        //--------------------------------------------------------------------
.
        public void setAliasName (
                String Name)
        {
                aliasName = Name;
                isrenamed = true;
        }
.
        //--------------------------------------------------------------------
        // mapAliasName
        // Maps the column name to alias name if isrenamed flag is used
        //--------------------------------------------------------------------
.
        public String mapAliasName (
                String columnName)
        {
                if (isrenamed == true)
                        return aliasName;
                else
                        return columnName;
        }
.
.
JdbcOdbcResultSetMetaData.java
.
In the method getColumnName() in JdbcOdbcResultSetMetaData.java,
the following line of code is added just before returning value to get the
alias name if necessary.
.
                value = resultSet.mapColumnName (value, column);
.
.
JdbcOdbcResultSetInterface.java
.
We also need to add this interface mapColumnName in
JdbcOdbcResultSetInterface.java
.
        //--------------------------------------------------------------------
        // mapColumnName
        // Given a column name, map it to the corresponding column rename in
        // the result set. If no column rename exist, return the original
        // column name. If the column number is out-of-range, return original
        // column name.
        //--------------------------------------------------------------------
.
        public String mapColumnName (
                String columnName,
                int column);
.
Here concludes all the changes for the defect.
.
Note 1: dots have been inserted on all blank lines to maintain
readability
.
Note 2: Raised against 1.2 as we have backported the JdbcOdbc
bridge from 1.2 to 1.1.7 so this seemed the most appropriate code base to report against.

(Review ID: 57679)

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