Sqlline date format

[vitalii...@gmail.com]

Hi all!

SqlLine uses toString() approach for showing a lot of datatypes.
https://github.com/julianhyde/sqlline/blob/master/src/main/java/sqlline/Rows.java#L183
Is it a good idea to rely on toString() for date-time types?

Dates are very locale-dependent. But toString() hardcodes the format. And the display of a date as a string couldn't be controlled by the client.
The similar to numeric data types (NumberFormat#format()), DateFormat could be used.

If it is a good idea I will open an issue here:
https://github.com/julianhyde/sqlline/issues

[Julian Hyde]

Your question has an incorrect assumption. sqlline does not call
Object.toString() on the value. It calls ResultSet.getString(int) on
the column. There is a lot of difference, especially in dateTime
scenarios. Consider TIMESTAMP. SQL TIMESTAMP values do not contain a
time zone, but java.sql.Timestamp values are implicitly based on the
UTC epoch and are printed in the local timezone. Thus,
rs.getObject(i).toString() or rs.getTimestamp(i).toString() will
produce a different string than rs.getString(i).

That said, being able to choose formats for particular columns or
particular data types would be really useful.

Maybe we could do something similar to SQL*Plus: you can associate a
formatter with a particular column alias using the COLUMN command[1].

Julian

[1] https://docs.oracle.com/cd/B19306_01/server.102/b14357/ch6.htm

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[Vitalii Diravka]

Sorry for being inaccurate. I didn't want to compare rs.getObject().toString() with rs.getString(i).
I only meant that implementation of rs.getString() assume using of toString() without any chance to use custom format of output.

To associate a formatter with particular column alias using the COLUMN command looks useful.
But is an acceptable the way (similar to numberFormatter) to use SqlLineOpts and loading properties?

[Julian Hyde]

Adding dateFormat, timeFormat, timestampFormat like numberFormat makes sense.

If you submit a pull request, please be sure to update the help, the manual, and add unit tests.

Julian

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