Some basic SQL Questions

[Steven O.]

First, this may not be the correct newsgroup. I have some relatively
basic questions on SQL. I tried to find a newsgroup that was
specifically just about SQL, and was surprised to find that all the
SQL-related newsgroups seem to be product related. But if I missed
something, and someone can steer me to a correct newsgroup, please do
so.

My specific questions:

1. I want to put comments in an SQL script. For example, I want
something like

CREATE TABLE myTable
(field1 CHAR(10), /* References the field1 table */
field2 DECIMAL(3,2) /* References field2 table */
);

Here, I've used C-style comments, but I don't think that works with
SQL. Is there any other syntax for sticking comments in a script?

2. I am writing my script based on some texts from an Oracle class I
took a year ago. But an online .pdf tutorial I found lists some data
types that are not in my text:
varchar2(n)
number(o,d)
Are these valid!?

3. Is there any kind of "memo" field in SQL? My database references
some text that may be arbitrary in length (like ingredients for a
recipe), and a way to link to memo fields would be helpful. Or, is
that the purpose of the varchar2 data type?

Thanks in advance for all replies.

Steve O.
Standard Antiflame Disclaimer: Please don't flame me. I may actually *be* an idiot, but even idiots have feelings.

[Jeff Boes]

At some point in time, Steven O.
<Steven@OpZZREMOVE_ALL_Zs_AND_ALL_BETWEEN_ZZComm.c om> wrote:

First, this may not be the correct newsgroup. I have some relatively
basic questions on SQL. I tried to find a newsgroup that was
specifically just about SQL, and was surprised to find that all the
SQL-related newsgroups seem to be product related. But if I missed
something, and someone can steer me to a correct newsgroup, please do
so.
Well, the answers you are most likely to get *here* will be specifically related
to PostgreSQL. However, its SQL dialect is pretty close to what most other
vendors support, so you should be OK in 97% of the things you try.

1. I want to put comments in an SQL script. For example, I want
something like

CREATE TABLE myTable
(field1 CHAR(10), /* References the field1 table */
field2 DECIMAL(3,2) /* References field2 table */
);

Perfectly acceptable in Pg. It also accepts the "--" line comment sequence (in
which everything after a bare, unquoted "--", until the end of the line, is a
comment).
2. I am writing my script based on some texts from an Oracle class I
took a year ago. But an online .pdf tutorial I found lists some data
types that are not in my text:
varchar2(n)
number(o,d)
Are these valid!?
Depends on the specific SQL you are using. In Pg, it's fine.

http://www.postgresql.org/docs/curre.../datatype.html


3. Is there any kind of "memo" field in SQL? My database references
some text that may be arbitrary in length (like ingredients for a
recipe), and a way to link to memo fields would be helpful. Or, is
that the purpose of the varchar2 data type?

"TEXT" is the unspecified length datatype in Pg. See the previous URL.
--
~~~~~~~~~~~~~~~~| Genius may have its limitations, but stupidity is not
Jeff Boes | thus handicapped.
jb***@qtm.net | --Elbert Hubbard (1856-1915), American author

[William ZHANG]

"Steven O." <Steven@OpZZREMOVE_ALL_Zs_AND_ALL_BETWEEN_ZZComm.c om> wrote:
hh********************************@4ax.com...

First, this may not be the correct newsgroup. I have some relatively
basic questions on SQL. I tried to find a newsgroup that was
specifically just about SQL, and was surprised to find that all the
SQL-related newsgroups seem to be product related. But if I missed
something, and someone can steer me to a correct newsgroup, please do
so. comp.databases.theory covers database theory. You can find some stuff
on SQL standards. For the basic SQL, some textbooks on SQL is helpful.

My specific questions:

1. I want to put comments in an SQL script. For example, I want
something like

CREATE TABLE myTable
(field1 CHAR(10), /* References the field1 table */
field2 DECIMAL(3,2) /* References field2 table */
);
The standard way is using "--". Like,
-- create a emp table
create table emp(
fno int, -- number of emp
fname char(8) -- name of emp.
)

Some DBMSs, e.g. PostgreSQL, also support /* ... */.

Here, I've used C-style comments, but I don't think that works with
SQL. Is there any other syntax for sticking comments in a script?

2. I am writing my script based on some texts from an Oracle class I
took a year ago. But an online .pdf tutorial I found lists some data
types that are not in my text:
varchar2(n)
number(o,d)
Are these valid!?
See ORACLE's manuals for details. They are valid data types
in ORACLE.

3. Is there any kind of "memo" field in SQL? My database references
some text that may be arbitrary in length (like ingredients for a
recipe), and a way to link to memo fields would be helpful. Or, is
that the purpose of the varchar2 data type?
Use BYTEA/TEXT in PostgreSQL.
Use BLOB/CLOB in standard SQL, ORACLE, ....
Use IMAGE/TEXT in MSSQL.

Thanks in advance for all replies.
You are welcome.

Steve O.
Standard Antiflame Disclaimer: Please don't flame me. I may actually

*be* an idiot, but even idiots have feelings.