Oracle SQL
Implementation of programming language SQLOracle RDBMS (usually referred as just Oracle) is a relational database management system created by Oracle Corporation.
Oracle is the most popular of SQL implementations; it was historically first commercial implementation of SQL, as well as the first one to support standard SQL‘93.
Oracle supports a number of different platforms, including Windows, Linux, Mac OS X and Sun Solaris.
Oracle procedural extension for SQL is called PL/SQL (for Procedural Language/Structured Query Language), and is based on Ada and Pascal languages. The third key language used in Oracle DBMS along with SQL and PL/SQL is Java.
PL/SQL supports program units (as functions, procedures and packages which can be compiled and stored in the database and executed at later time and anonymous blocks which can not be stored and are used only from scripts). PL/SQL has a variety of numeric, character and date datatypes, supports control flow statements like conditional statemens and loops and handles three types of containers called collections — variable size arrays, associative arrays and nested tables.
Database development and administration and application development for Oracle DBMS can be done using a variety of software tools. Tools provided by Oracle Corporation include:
 SQL*Plus — a commandline tool for executing SQL and PL/SQL commands interactively or from a script; is commonly used as a default installation interface found in every Oracle installation.
 iSQL*Plus — a webbrowserbased tool for executing SQL commands.
 Oracle SQL Developer — an IDE for SQL development.
 Oracle Forms — an IDE for creating applications that interact with database; is commonly used to create data entry systems and graphical interfaces for databases.
 Oracle Reports — an IDE for creating reports based on data stored in the database.
 Oracle JDeveloper — an IDE which allows development in SQL, PL/SQL and Java.
Examples of thirdparty tools are:
 TOAD — a Windows IDE created by Quest Software which supports Oracle, Microsoft SQL Server, MySQL and IBM DB2;
 PL/SQL Developer — an IDE created by Allround Automations.
Examples:
Hello, World!:
Example for versions Oracle 10g SQL, Oracle 11g SQL‘Hello, World!’ string is selected from builtin table dual
which is used for queries which don’t need data from real tables.
select 'Hello, World!'
from dual;
Factorial:
Example for versions Oracle 10g SQL, Oracle 11g SQLPure SQL doesn’t support loops, recursions or userdefined functions. This example shows one possible workaround which uses

pseudocolumn
level
to construct a pseudotable containing numbers 1 through 16, 
aggregate function
sum
which allows to sum the elements of a set 
and math functions
exp
andln
to replace multiplication (required to calculate the factorial) with addition (provided by SQL).
Note that 0! will not be present in the return, since trying to calculate ln(0) produces an exception.
select t2.n  '! = '  round(exp(sum(ln(t1.n))))
from
( select level n
from dual
connect by level <= 16) t1,
( select level n
from dual
connect by level <= 16) t2
where t1.n<=t2.n
group by t2.n
order by t2.n
Fibonacci numbers:
Example for versions Oracle 10g SQL, Oracle 11g SQLPure SQL doesn’t support loops, recursions or userdefined functions. Besides, concatenating fields from multiple rows of a table or a subquery is not a standard aggregate function. This example uses:

Binet’s formula and math functions
round
,power
andsqrt
to calculate nth Fibonacci number;  pseudocolumn level to construct a pseudotable t1 containing numbers 1 through 16;

builtin function
SYS_CONNECT_BY_PATH
to concatenate the resulting numbers in ascending order.
SELECT REPLACE(MAX(SYS_CONNECT_BY_PATH(fib', ', '/')),'/','')'...' fiblist
FROM (
SELECT n, fib, ROW_NUMBER()
OVER (ORDER BY n) r
FROM (select n, round((power((1+sqrt(5))*0.5, n)power((1sqrt(5))*0.5, n))/sqrt(5)) fib
from (select level n
from dual
connect by level <= 16) t1) t2
)
START WITH r=1
CONNECT BY PRIOR r = r1;
Factorial:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example shows the use of model
clause, available since Oracle 10g. It allows arraylike processing of query rows. Each row has two columns — iteration number (stored in n
) and its factorial (stored in f
).
select n  '! = '  f factorial
from dual
model
return all rows
dimension by ( 0 d )
measures ( 0 f, 1 n )
rules iterate (17)
( f[iteration_number] = decode(iteration_number, 0, 1, f[iteration_number1]*iteration_number),
n[iteration_number] = iteration_number
);
Fibonacci numbers:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example shows the use of model
clause, available since Oracle 10g. It allows arraylike processing of query rows. Each row has two columns — Fibonacci number itself (stored in f) and concatenation of all Fibonacci numbers less than or equal to the current Fibonacci number (stored in s). Iterative aggregation of Fibonacci numbers in the same query that they were generated is easier than aggregating them separately.
select max(s)  ', ...'
from
(select s
from dual
model
return all rows
dimension by ( 0 d )
measures ( cast(' ' as varchar2(200)) s, 0 f)
rules iterate (16)
( f[iteration_number] = decode(iteration_number, 0, 1, 1, 1, f[iteration_number1] + f[iteration_number2]),
s[iteration_number] = decode(iteration_number, 0, to_char(f[iteration_number]), s[iteration_number1]  ', '  to_char(f[iteration_number]))
)
);
Hello, World!:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example accomplishes the task by means of anonymous PL/SQL block, which uses standard package dbms_output
to print the message to standard output.
begin
dbms_output.put_line('Hello, World!');
end;
Factorial:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example calculates factorials iteratively by means of PL/SQL.
declare
n number := 0;
f number := 1;
begin
while (n<=16)
loop
dbms_output.put_line(n  '! = '  f);
n := n+1;
f := f*n;
end loop;
end;
Fibonacci numbers:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example implements iterative definition of Fibonacci numbers by means of PL/SQL. Already calculated numbers are stored in varray
, PL/SQL analogue of array in other languages.
declare
type vector is varray(16) of number;
fib vector := vector();
i number;
s varchar2(100);
begin
fib.extend(16);
fib(1) := 1;
fib(2) := 1;
s := fib(1)  ', '  fib(2)  ', ';
for i in 3..16 loop
fib(i) := fib(i1) + fib(i2);
s := s  fib(i)  ', ';
end loop;
dbms_output.put_line(s  '...');
end;
Quadratic equation:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example was tested in SQL*Plus and TOAD.
Pure SQL allows to input values at runtime in the form of substitution variables. To define a substitution variable, use its name (in this case A, B and C) with an ampersand &
before it each time you need to reference it. When the query needs to be executed, you will receive a prompt to enter the values of the variables. Each reference to such variable will be replaced with its value, and the resulting query will be executed.
There are several ways to input the values for substitution variables. In this example first reference to each variable has double ampersand &&
before its name. This way the value of the variable has to be entered only once, and all following references will be replaced with the same value (using single ampersand in SQL*Plus asks to enter the value for each reference to the same variable). PL/SQL Developer requires that all variables have single &
before their names, otherwise ORA01008 “Not all variables bound” exception will be raised.
Note that the references are substituted with the values “as is”, so negative values of coefficients have to be entered in brackets.
First line of the example sets the character for decimal separator which is used when the numbers are converted into strings.
The query itself is composed of four different queries. Each query returns a string containing the result of calculations for one case of quadratic equation, and returns nothing for three other cases. The results of each query are united to produce the final result.
alter session set NLS_NUMERIC_CHARACTERS='. ';
select 'Not a quadratic equation.' ans
from dual
where &&A = 0
union
select 'x = '  to_char(&&B/2/&A)
from dual
where &A != 0 and &B*&B4*&A*&&C = 0
union
select 'x1 = '  to_char((&B+sqrt(&B*&B4*&A*&C))/2/&A)  ', x2 = '  to_char(&Bsqrt(&B*&B4*&A*&C))/2/&A
from dual
where &A != 0 and &B*&B4*&A*&C > 0
union
select 'x1 = ('  to_char(&B/2/&A)  ','  to_char(sqrt(&B*&B+4*&A*&C)/2/&A)  '), ' 
'x2 = ('  to_char(&B/2/&A)  ','  to_char(sqrt(&B*&B+4*&A*&C)/2/&A)  ')'
from dual
where &A != 0 and &B*&B4*&A*&C < 0;
CamelCase:
Example for versions Oracle 10g SQL, Oracle 11g SQLThis example uses Oracle SQL regular expressions. First use of regexp_replace
replaces all digits with spaces — this is necessary for further initcap
usage (this function treats digits as parts of the words and doesn’t capitalize following letters). Next, initcap
converts all words to lowercase with first letter capitalized. Finally, second use of regexp_replace
removes all punctuation and spaces from the string.
&TEXT is substitution variable, which allows to input different strings without rewriting the select statement.
select regexp_replace(initcap(regexp_replace('&TEXT', '[[:digit:]]', ' ')), '([[:punct:]  [:blank:]])', '')
from dual
CamelCase:
Example for versions Oracle 11g SQLThis example uses Oracle regular expressions combined with PL/SQL. regex_substr
returns a substring of text
that is occurrence
‘s match to the given regular expression.
declare
text varchar2(100) := '&user_input';
word varchar2(100);
camelcase varchar2(100);
occurrence number := 1;
begin
loop
word := regexp_substr(text, '[[:alpha:]]+', 1, occurrence);
exit when word is null;
camelcase := camelcase  initcap(word);
occurrence := occurrence + 1;
end loop;
dbms_output.put_line(camelcase);
end;
Quadratic equation:
Example for versions Oracle 11g SQLdeclare
A number := '&A';
B number := '&B';
C number := '&C';
D number := B * B  4 * A * C;
begin
if A = 0 then
dbms_output.put_line('Not a quadratic equation.');
return;
end if;
if D = 0 then
dbms_output.put_line('x = '  to_char(B/2/A));
elsif D > 0 then
dbms_output.put_line('x1 = '  to_char((Bsqrt(D))/2/A));
dbms_output.put_line('x2 = '  to_char((B+sqrt(D))/2/A));
else
dbms_output.put_line('x1 = ('  to_char(B/2/A)  ', '  to_char(sqrt(D)/2/A)  ')');
dbms_output.put_line('x2 = ('  to_char(B/2/A)  ', '  to_char(sqrt(D)/2/A)  ')');
end if;
end;
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