Обсуждение: Booleans - Why in Postgres and not in Oracle or Mysql?
I like Postgres's boolean type - why do you suppose neither Mysql nor Oracle has bothered to implement it? Booleans are in the SQL-99 spec. CSN __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
> -----Original Message----- > From: pgsql-general-owner@postgresql.org [mailto:pgsql-general- > owner@postgresql.org] On Behalf Of CSN > Sent: Thursday, May 05, 2005 11:57 AM > To: pgsql-general@postgresql.org > Subject: [GENERAL] Booleans - Why in Postgres and not in Oracle or Mysql? > > I like Postgres's boolean type - Me too. > why do you suppose > neither Mysql nor Oracle has bothered to implement it? Probably they just create a domain using a char which can take on two values (e.g. 't'/'f' or 1/0). Oracle 10 has a bit data type (which is a boolean for all intents and purposes): B.1 BIGINT B.2 BINARY B.3 BIT B.4 BLOB B.5 CHAR B.6 CLOB B.7 DATE B.8 DECIMAL B.9 DOUBLE PRECISION B.10 FLOAT B.11 INTEGER B.12 LONG B.13 LONG RAW B.14 LONG VARBINARY B.15 LONG VARCHAR B.16 NUMBER B.17 NUMERIC B.18 RAW B.19 REAL B.20 ROWID B.21 SMALLINT B.22 TIME B.23 TIMESTAMP B.24 TINYINT B.25 VARBINARY B.26 VARCHAR B.27 VARCHAR2 MySql has a partial Boolean implementation. From http://dev.mysql.com/doc/mysql/en/numeric-type-overview.html: BOOL , BOOLEAN These are synonyms for TINYINT(1). The BOOLEAN synonym was added in MySQL 4.1.0. A value of zero is considered false. Non-zero values are considered true. In the future, full boolean type handling will be introduced in accordance with standard SQL. > Booleans are in the SQL-99 spec. Probably, MySQL and Oracle will have Boolean types eventually with full compatibility to the standard. > CSN > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > > ---------------------------(end of broadcast)--------------------------- > TIP 9: the planner will ignore your desire to choose an index scan if your > joining column's datatypes do not match
--- Dann Corbit <DCorbit@connx.com> wrote: > > why do you suppose > > neither Mysql nor Oracle has bothered to implement > it? > > Probably they just create a domain using a char > which can take on two > values (e.g. 't'/'f' or 1/0). Oracle 10 has a bit > data type (which is a > boolean for all intents and purposes): Could a bit handle NULL's though? CSN __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
CSN wrote: > I like Postgres's boolean type - why do you suppose > neither Mysql nor Oracle has bothered to implement it? > Booleans are in the SQL-99 spec. Fear of breaking old applications -- Peter Eisentraut http://developer.postgresql.org/~petere/
On Thu, 2005-05-05 at 15:28, CSN wrote:
>
> --- Dann Corbit <DCorbit@connx.com> wrote:
> > > why do you suppose
> > > neither Mysql nor Oracle has bothered to implement
> > it?
> >
> > Probably they just create a domain using a char
> > which can take on two
> > values (e.g. 't'/'f' or 1/0). Oracle 10 has a bit
> > data type (which is a
> > boolean for all intents and purposes):
>
> Could a bit handle NULL's though?
>
ISTR there is some debate on whether Booleans should allow NULL and
thats why the boolean type is still in the extended set of sql spec and
not core.
Inceidentally MySQL's boolean is really scary... it's not just than 0 =
false and 1 = true, its 0 = false and (n >= 1) is true. IMHO that
sounds like a recipe for creating subtle bugs.
Robert Treat
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