[jira] Commented: (DERBY-1804) [DOC] CAST conversions between data types table is incorrect in Reference manual in some VARCHAR and TIMESTAMP cases

["Laura Stewart (JIRA)" <de...@db.apache.org>]

    [ http://issues.apache.org/jira/browse/DERBY-1804?page=comments#action_12433912 ] 
            
Laura Stewart commented on DERBY-1804:
--------------------------------------

Susan - As I read the CAST table, the "Source" is the first column.  The "Target" is the first row.  When I look at source=SMALLINT (in the second row), there is a dash under the VARCHAR column, meaning that you cannot cast a SMALLINT column as a VARCHAR.  Conversely, the table indicates that you can cast a VARCHAR as a SMALLINT.

I believe that your tests were from SMALLINT, INTEGER, BIGINT and DECIMAL to VARCHAR?  
The table currently does show that you cannot perform those casts.
Do you also mean that you can't cast a VARCHAR as a SMALLINT, INTEGER, BIGINT or DECIMAL  ???

I have corrected the DATE to TIMESTAMP and TIME to TIMESTAMP columns.

I produce a patch once you let me know about VARCHAR.

> [DOC] CAST conversions between data types table is incorrect in Reference manual in some VARCHAR and TIMESTAMP cases
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-1804
>                 URL: http://issues.apache.org/jira/browse/DERBY-1804
>             Project: Derby
>          Issue Type: Bug
>          Components: Documentation
>    Affects Versions: 10.2.2.0
>            Reporter: Susan Cline
>         Assigned To: Laura Stewart
>
> The CAST function documentation contains a table which lists the explicit conversions between data types.
> http://db.apache.org/derby/docs/10.2/ref/rrefsqlj33562.html
> For the 'SOURCE' values (the columns) of SMALLINT, INTEGER, BIGINT and DECIMAL the CAST to VARCHAR is listed.  However, they should not be listed because this cast is not allowed.  See the output below;
> ij> create table smallint_tab(id integer, col2 smallint);
> 0 rows inserted/updated/deleted
> ij> insert into smallint_tab values (1, 10);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as varchar(10)) from smallint_tab;
> ERROR 42846: Cannot convert types 'SMALLINT' to 'VARCHAR'.
> Also from integer to varchar does not work: 
> ij> create table int_tab (id integer, col2 integer);
> 0 rows inserted/updated/deleted
> ij> insert into int_tab values (1, 10);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as varchar(20)) from int_tab;
> ERROR 42846: Cannot convert types 'INTEGER' to 'VARCHAR'.
> Bigint neither: 
> ij> create table bigint_tab (id integer, col2 bigint); 
> 0 rows inserted/updated/deleted 
> ij> insert into bigint_tab values (1, 10); 
> ij> select cast(col2 as varchar(20)) from bigint_tab; 
> ERROR 42846: Cannot convert types 'BIGINT' to 'VARCHAR'. 
> Nor decimal: 
> ij> create table decimal_tab (id integer, col2 decimal); 
> 0 rows inserted/updated/deleted 
> ij> insert into decimal_tab values (1, 1.88); 
> 1 row inserted/updated/deleted 
> ij> select cast(col2 as varchar(3)) from decimal_tab; 
> ERROR 42846: Cannot convert types 'DECIMAL' to 'VARCHAR'. 
> The Cast from DATE to TIMESTAMP and TIME to TIMESTAMP also are not allowed, although they
> are listed.  They need to be removed;
> ij> create table date_tab (id integer, col2 date);
> 0 rows inserted/updated/deleted
> ij> insert into date_tab values (1, CURRENT_DATE);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as timestamp) from date_tab;
> ERROR 42846: Cannot convert types 'DATE' to 'TIMESTAMP'.
> ij> create table time_tab (id integer, col2 time);
> 0 rows inserted/updated/deleted
> ij> insert into time_tab values (1, CURRENT_TIME);
> 1 row inserted/updated/deleted
> ij> select cast(col2 as timestamp) from time_tab;
> ERROR 42846: Cannot convert types 'TIME' to 'TIMESTAMP'.

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