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Just for discussion, here are two *hypothetical*
database systems with a listing of corresponding
datatypes. (no they are real but let's not get
into the vendors). Both of these can issue and
accept XML. Without a way to spec datatypes,
just how good are my chances that the db will
handle the data not as I see fit, but such that
regardless of the db, I or anyone that uses the
XML, will get the same results.
Doesn't this become an issue for anyone who
tries to spec a common XML document type
for say, ebXML? Are elements and attribute
names sufficient? Today, we have to write
a lot of code to handle this. I don't think
that is a good solution for interop.
len
***************************************************************************
Fixed Length String
System 1: CHAR(n)- limit 2KB
System 2: CHAR(n), CHARACTER(n)- limit 255 (6.5)- limit 8KB (7.0)
Variable Length String
System 1: VARCHAR2(n), VARCHAR(n)- limit 4KB in a column- limit 32KB in a variable- VARCHAR is obsolete
System 2: VARCHAR(n), CHAR VARYING(n), CHARACTER VARYING(n)- limit 255 (6.5)- limit 8KB (7.0)
Integer
System 1: INTEGER, INTEGER(n), SMALLINT
System 2: INTEGER (4 bytes), INT (4 bytes), SMALLINT (2 bytes), TINYINT (1 byte), BIT (1 bit)
Fixed Point
System 1: NUMBER, NUMBER(n), NUMBER(n,d),FLOAT, FLOAT(n), FLOAT(n,d)
System 2: NUMERIC, NUMERIC(n), NUMERIC(n,d),DECIMAL, DECIMAL(n), DECIMAL(n,d),DEC, DEC(n), DEC(n,d),MONEY, SMALLMONEY
Floating Point
System 1: DECIMAL
System 2: FLOAT, FLOAT(n), DOUBLE PRECISION, REAL,
Date
System 1: DATE
System 2: DATETIME, SMALLDATETIME, TIMESTAMP- TIMESTAMP auto-updated
Binary
System 1: RAW(n)- limit 255 bytes
System 2: BINARY(n), VARBINARY(n), BINARY VARYING(n)- limit 255 (6.5)- limit 8KB (7.0)
Large String
System 1: LONG, LONG VARCHAR- limit 2GB- limit one per table rowCLOB- limit 4GB
System 2: TEXT- limit 2GB
Large Binary
System 1: LONG RAW- limit 2GB- limit one per table rowBLOB- limit 4GB
System 2: IMAGE- limit 2GB
Multi-byte chars
System 1: NCHAR(n)NVARCHAR(n)NCLOB- same limits as CHAR, VARCHAR, CLOB
System 2: NCHAR(n), NATIONAL CHAR(n), NATIONAL CHARACTER(n)NVARCHAR(n), NATIONAL CHAR VARYING(n), NATIONAL CHARACTER VARYING(n)NTEXT, NATIONAL TEXT- same limits as CHAR, VARCHAR, TEXT
Row Identifier
System 1: implicit ROWID column
System 2: (use an IDENTITY column)
Secure OS Label
System 1: MLSLABEL, RAW MLSLABEL
System 2: <not supported>
128-bit Unique Number(UUID, GUID)
System 1: <not supported>
System 2: UNIQUEIDENTIFIER (version 7.0 only)
From: Jonathan Robie [mailto:jonathan.robie@datadirect-technologies.com]
I don't know how to design a language that will avoid any possible
philosophical or aesthetic objections on XML-Dev. I'm an engineer, not a
deity. But if you give me a concrete problem to solve, I think we have a
Working Group that might be able to solve it.
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