Hello

As I mention in a previous email, those are known errors.
- The size/length for char and varchar are wrong in DatabaseMetaData
and ResultSetMetaData when the character set is multi-byte.
- The precision for numeric and decimals are wrong in
ResultSetMetaData.

Because the solution of those bugs can take some time, please fill two
bugs in the sourceforge bug list, thus we don't forget this issue until we
can patch it.

Regards
Blas Rodriguez Somoza

----- Original Message -----
From: "tsangccn" <tsang_cn@...>
To: <Firebird-Java@yahoogroups.com>
Sent: Tuesday, August 27, 2002 7:43 AM
Subject: [Firebird-Java] Incorrect DatabaseMeta and ResultSetMetaData


> Hello,
>
> I have download firebirdsql from CVS and rebuild.
> The results of DatabaseMetaData and ResultSetMetaData have been patched.
> But I think that there are still some errors.
> I have some questions want to clarify.
>
> Take the sample I used last time
> (the VARCHAR(10) column is CHARSET UNICODE_FSS)
>
> Database MetaData
>
> type COLUMN_SIZE DECIMAL_DIGITS
>
> VARCHAR(10) 30 0
> INTEGER 10 0
> DECIMAL(11,2) 11 2
> DECIMAL(5,4) 5 4
> DATE 10 0
> TIME 8 0
> TIMESTAMP 19 0
>
> ResultSet MetaData
>
> type getColumnDisplaySize getPrecision getScale
>
> VARCHAR(10) 30 30 0
> INTEGER 11 10 0
> DECIMAL(11,2) 8 8 2
> DECIMAL(5,4) 4 4 4
> DATE 10 10 0
> TIME 8 8 0
> TIMESTAMP 19 19 0
>
> I have try using NUMERIC instead of DECIMAL, but it returns the same
> result.
>
> ------
>
> The following is extracted from
>
http://java.sun.com/j2se/1.4/docs/api/java/sql/DatabaseMetaData.html#getColu
mns(java.lang.String,%20java.lang.String,%20java.lang.String,%20java.lang.St
ring)
>
> 7. COLUMN_SIZE int => column size. For char or date types this is the
> maximum number of characters, for numeric or decimal types this is
> precision.
> 8. BUFFER_LENGTH is not used.
> 9. DECIMAL_DIGITS int => the number of fractional digits
>
> ------
>
> The following is extracted from API documentation for ResultSetMetaData
>
> getColumnDisplaySize
> --------------------
> public int getColumnDisplaySize(int column)
> throws SQLException
>
> Indicates the designated column's normal maximum width in characters.
>
> Parameters:
> column - the first column is 1, the second is 2, ...
> Returns:
> the normal maximum number of characters allowed as the width
> of the designated column
> Throws:
> SQLException - if a database access error occurs
>
> getPrecision
> ------------
> public int getPrecision(int column)
> throws SQLException
>
> Get the designated column's number of decimal digits.
>
> Parameters:
> column - the first column is 1, the second is 2, ...
> Returns:
> precision
> Throws:
> SQLException - if a database access error occurs
>
> ------
>
> The following is extracted from
> http://www.ibphoenix.com/ibp_data_types.html
>
> To summarise the manual:
>
> * Precision means the total number of digits stored - inclusive of
> both sides of the decimal point.
> * Scale is the number of those digits that are to the right of the
> decimal point.
> * Numeric means that the largest value stored is dictated by
> (precision-scale).
> * Decimal means that numbers with larger than precision-scale will
> be stored; decimal specifies at least in contrast to numerics' the most.
>
> ------
>
> The following is extracted from
>
http://www.ibphoenix.com/netfradb/search.nfs?a=knowledgebase&l=;KNOWLEDGEBAS
E.PAGES;ID=%27482%27
>
> Once you use precision 10 or greater, InterBase internally stores the
> value as a 64-bit IEEE double float.
> If you use precision 9 or less, InterBase uses 16-bit or 32-bit
> integer type with a scale value to store the number, ......
>
> ------
>
> (1) VARCHAR(10) CHARSET UNICODE_FSS
> * According to the API documentation, the COLUMN_SIZE of
> DatabaseMetaData should return maximum number of charcters for char (&
> varchar)
> But interclient and firebirdsql returns 30. I think it should
> return 10.
> I have tested with DB2 and Oracle, they do return 10.
> Please note that 30 is the maximum number of BYTES for a maximum
> of 10 UTF8 CHARACTERS.
> * According to API doc, ResultSetMetaData.getColumnDisplaySize()
> should be maximum width characters, and thus 10 in the sample, but
> when count display size, ...
> * ResultSetMetaData.getPrecision() - for char or varchar, I think
> precision is also the maximum number of characters.
> So it should return 10.
> I have tested with DB2 and Oracle, they do return 10.
>
> ------
>
> (2) NUMERIC(11,2)
> * DatabaseMeta COLUMN_SIZE return 11. It is OK.
> * The API doc for ResultSetMetaData.getPrecision() returns precision,
> so it should be 11.
> But firebirdsql returns 8. As it is stored in IEEE double, 8 is
> the internal buffer size in BYTES but not the precision.
> * The maximum format for NUMERIC(11,2) as displayed is -999999999.99
> (without thousands separator).
> So ResultSetMetaData.getColumnDisplaySize() should return 13. But
> firebirdsql returns 8.
>
> ------
>
> (3) NUMERIC(5,4)
> * DatabaseMeta COLUMN_SIZE return 5. It is OK.
> * The API doc for ResultSetMetaData.getPrecision() returns precision,
> so it should be 5.
> But firebirdsql returns 4. As it is stored in 16-bit or 32-bit
> integer, 4 is the internal buffer size in BYTES but not the precision.
> * The maximum format for NUMERIC(5,4) as displayed is -9.9999
> (without thousands separator).
> So ResultSetMetaData.getColumnDisplaySize() should return 7. But
> firebirdsql returns 4.
>
> ------
>
> Please check and a patch is appreciated.
>
> Thanks
> CN
>
>
>
>
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