Big disadvantages of default is:
1. Immediately update all rows in table.
Interesting only if all or most already existed rows will use this value.
2. Less readable, this is important for me.
I prefer this scenario:
ALTER TABLE ... ADD null able;
COMMIT;
UPDATE ...
COMMIT;
ALTER TABLE ... ALTER ... SET NOT NULL;
COMMIT;
For backward compatibility (currently I must support FB2.5) I using this SP
instead SET NOT NULL:
CREATE OR ALTER PROCEDURE MASA$Set_Null_Flag(Relation_Name RDB$Relation_Name,
Field_Name RDB$Field_Name, Not_Null SMALLINT)
AS
DECLARE major INTEGER;
DECLARE ds VARCHAR(500);
DECLARE nf VARCHAR(20);
BEGIN
major=COALESCE(SubStrFromStr(rdb$get_context('SYSTEM','ENGINE_VERSION'),'.',0),0);
IF(major>=3)THEN BEGIN
nf = ' DROP NOT NULL;';
IF(Not_Null = 1) THEN nf = ' SET NOT NULL;';
ds = 'ALTER TABLE '||TRIM(Relation_Name)||' ALTER '||TRIM(Field_Name)||nf;
END ELSE BEGIN
nf = 'NULL';
IF(Not_Null = 1) THEN nf = '1';
ds = 'UPDATE RDB$RELATION_FIELDS SET RDB$NULL_FLAG = '||nf||' WHERE
RDB$FIELD_NAME='''||TRIM(Field_Name)||''' AND
RDB$RELATION_NAME='''||TRIM(Relation_Name)||''';';
END
EXECUTE STATEMENT ds WITH AUTONOMOUS TRANSACTION;
END
Slavek
On 13.10.2016 17:49, Jiří Činčura wrote:
>> 1.add field with "default"
> Which you can later remove.
>
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, SlashDot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at
https://lists.sourceforge.net/lists/listinfo/firebird-devel
