Oracle Academy

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Oracle Academy
Prof. Carmen Popescu Oracle Academy Lead Adjunct
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Forma generala a comenzii SELECT

• SELECT expresii
• FROM tabele
• WHERE conditii
• In clauza select pot aparea coloane, sau expresii
• Ordinea operatorilor / -
• Operatorii logici AND, OR (in aceasta ordine)

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BETWEEN

• SELECT from employees
• WHERE
• department_id BETWEEN 10 AND 30
• ?
• SELECT from employees
• WHERE
• department_id gt10 AND
• department_idlt30
• Departamentul 20 ESTE afisat

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IN

• SELECT from employees
• WHERE
• department_id IN (10,30)
• ?
• SELECT from employees
• WHERE
• department_id10 OR
• department_id30
• Departamentul 20 NU ESTE afisat

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NULL

• 5NULL gt NULL
• La ordonare crescatoare valorile NULL sunt puse
  la sfarsit
• La ordonare descrescatoare NULL apare la inceput

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ALIAS DE COLOANA (AS)

• SELECT salary0.25salary
• FROM employees
• SELECT salary0.25salary
• AS New Salary
• FROM employees
• SELECT salary0.25salary
• AS New Salary
• FROM employees
• gt EROARE

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ALIAS DE COLOANA (AS)

• SELECT first_name last_name
• AS Numele
• FROM employees
• SELECT first_name last_name
• AS Numele
• FROM employees

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ALIAS DE COLOANA (AS)

• Ghilimelele la alias sunt obligatorii cand
• Aliasul e compus din doua sau mai multe cuvinte
• Dorim ca aliasul sa fie scriscu litere mici

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DESCRIBE
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LIKE

• SELECT from employees
• WHERE first_name LIKE a
• afiseaza toate persoanele cu un a oriunde in
  prenume
• SELECT from employees
• WHERE first_name LIKE _ _a
• afiseaza persoanele cu un a pe a treia pozitie
  din nume
• - oricate caractere (inclusiv nici unul)
• _ - un singur caracter

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LIKE

• SELECT from employees
• WHERE job_title LIKE \_ _ _
• ESCAPE \
• afiseaza persoanele pt. care in job_title, dupa
  caracterul _ mai exista exact doua caractere
• Cu clauza ESCAPE am precizat ca sau _ precedate
  de \ vor
• fi tratate ca si caractere
• normale ce trebuie sa
• apara in text nu ca
• wildchar.

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ORDER BY

• SELECT FROM employees
• ORDER BY last_name ASC,
• salary DESC
• SELECT first_name,salary,
• department_id
• FROM employees
• ORDER BY 2
• Se sorteaza dupa a doua
• expresie din clauza SELECT,
• adica dupa salary