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]

Re: Some basic SQL Questions

At some point in time, Steven O.
<Steven@OpZZREM OVE_ALL_Zs_AND_ ALL_BETWEEN_ZZC omm.com> wrote:
[color=blue]
>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.[/color]

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.
[color=blue]
>
>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 */
>);
>[/color]

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).
[color=blue]
>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!?[/color]

Depends on the specific SQL you are using. In Pg, it's fine.

http://www.postgresql.org/docs/current/static/datatype.html

[color=blue]
>
>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?
>[/color]

"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.
jboes@qtm.net | --Elbert Hubbard (1856-1915), American author

[William ZHANG]

Re: Some basic SQL Questions


"Steven O." <Steven@OpZZREM OVE_ALL_Zs_AND_ ALL_BETWEEN_ZZC omm.com> wrote:
hh73001fej4r1ho trvk030ubmpffdc 6r0a@4ax.com...[color=blue]
> 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.[/color]
comp.databases. theory covers database theory. You can find some stuff
on SQL standards. For the basic SQL, some textbooks on SQL is helpful.
[color=blue]
>
> 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 */
> );[/color]

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 /* ... */.
[color=blue]
>
> 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!?[/color]

See ORACLE's manuals for details. They are valid data types
in ORACLE.
[color=blue]
>
> 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?[/color]

Use BYTEA/TEXT in PostgreSQL.
Use BLOB/CLOB in standard SQL, ORACLE, ....
Use IMAGE/TEXT in MSSQL.
[color=blue]
>
> Thanks in advance for all replies.[/color]

You are welcome.
[color=blue]
>
> Steve O.
>
>
> Standard Antiflame Disclaimer: Please don't flame me. I may actually[/color]
*be* an idiot, but even idiots have feelings.