SQL general
Last updated on
2013/2557
１２
１７
,
a full
moon day;
SQL general
Last updated on
2013/2557 １２ １７,
a full
moon day;
Also see: Command;
oracle;
SQL.htm;
1st to understand
OSI
layers existence in an era of binary to duo-binary;
Difficulties are: so many N protocols exist in Network_layer;
so many N sessions
[assuming 1 window is 1 session]
exist in Session_layer;
so many N RDBMS systems such as:
DB2, Microsoft Access,
MySQL, Oracle,
PostgreSQL, SQL Server,
... ; so many N
languages can program
all
layers in OSI e.g. C#,
Java,
Perl, Ruby, ... ; so many
N frames exist Physical_layer;
2nd to understand
ER model and its relational
concept; Difficulties are: so many N
meta data relationships exist in Logic_link_layer;
so many N nested and complex mapping exists, therefore must
understand "complex", and "mapping"
and then nested statements, for example SELECT
columnABC from tableXYZ
WHERE SELECT
very simple 2
nested "selects" statement is here, and notice that WHERE statement makes 1
nested condition such as IJK and LMN tables join together with all columns
inside, and also notice that the very simple 2 nested "selects" statement does
not contain databases' storage allocation and file system formats either
* from tableIJK and tableLMN is a simple statement, however when involving
transactions in several databases combination with Network_layer protocols AND
programming language AND
SQL syntax AND
SQL semantic becomes
security concern;
3rd to understand relational algebra and relational
calculus; Difficulties are: so many N
containers exist in Transport_layer;
so many N embedded applications exist in Application_layer and
Presentation_layer;
4th to understand
SQL syntax
vs. semantic;
Difficulties are: so many N
tables exist in a database; so many N
columns exist in a table; so many N
file formats in a system;
so many . dots in a system,
e.g. abc CONTAINER
. efg
DATABASE .
ijk TABLE
. xyz
COLUMN;
5th
to understand data processing; Difficulties are:
so many N human beings' error is the most difficult to
query,
to trace, ... ; so many
N levels of human beings, such as ... , 2 zeros, 3 zeros, 4 zeros, 5 zeros,
... diff accountings ... ; One & only 1 human
beings kind makes N mistake(s) ...
;
Remark: The following
SQL
statement is an imaginary statement to allocate our Earth planet's current
location, and notice
that this
query is not 2,3 dimensional,
2 vice versa
3;
SQL Commands
e.g. DELETE, GROUP BY, INSERT, SELECT,
UPDATE, ... ;
SELECT Earth_current_location_at_present from Table1,
Table2, Table3, Table4
WHERE
Orbiter1.Table1.ParallelTime1 = Orbiter2.Table2.Parallel2
AND
Orbiter3.Table3.ParallelTime3 = Orbiter4.Table4.ParallelTime4
GROUP BY 24mm_natural_time;
In
2013/2557, IFF
Oracle
Database 12c, also see:
ADR,
PGA,
SGA,
... ;
declare, begin, (execute immediate, for, loop, using), end, ... ;
Keyword e.g.
doko WHERE "using" might be for Microsoft's
BASIC; "loop" means kuru kuru
WHILE logic flows until done;
for, common among programming languages;
"execute immediate" is new in Oracle Database 12c
... ;
In 2008, IFF Oracle DB, 6 recommended books are Oracle Database 11g New Features, Oracle Database 11g DBA Handbook, Oracle Automatic Storage Management, Oracle Database 11g SQL, Oracle Database AJAX & PHP Web Development, and Oracle Database 11g PL/SQL Programming, also see: www.oraclepressbooks.com;
...
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