Using basic select statement in oracle database
- 1. USING BASIC SELECT STATEMENT Created by: MD. MAHBUBUL ALAM MASUM
- 2. WE ARE GOING TO USE THE HUMAN RESOURCES (HR) SCHEMA
- 3. SELECT (COLUMN_NAME) FROM (TABLE_NAME);
- 4. SELECT ALL COLUMN You can select all column by select* keyword.
- 8. RULES OF PREDEDENCE • Multiplication and division occur before addition and subtraction. • Operators of the same priority are evaluated from left to right. • Parentheses are used to override the default precedence or to clarify the statement.
- 10. NULL VALUE # Null is a value that is unavailable, unassigned, unknown or inapplicable. # Null is not the same as zero or a blank space.
- 11. DEFINING A NULL VALUE
- 12. ARITHMETIC EXPRESSIONS CONTAINING A NULL VALUE EVALUATE TO NULL.
- 13. COLUMN ALIAS # COLUMN ALIAS MEANS RENAME A COLUMN HEADING. # COLUMN ALIAS IMMIDIATELY FOLLOW THE COLUMN NAME.
- 14. USING COLUMN ALIASES You can use optional AS keyword between the column name and the alias. Requires double quotation marks if it contains spaces or special characters, or if it is case-sensitive
- 15. CONCATENATION OPERATOR # A concatenation operator Links columns or character strings to other columns # it Is represented by two vertical bars (||) # it Creates a resultant column that is a character expression
- 16. LITERAL CHARACTER STRINGS • A literal is a character, a number, or a date that is included in the SELECT statement. • Date and character literal values must be enclosed within single quotation marks. • Each character string is output once for each row returned.
- 17. USING LITERAL CHARACTER STRINGS
- 18. ALTERNATIVE QUOTE (Q) OPERATOR • Specify your own quotation mark delimiter. • Select any delimiter. • Increase readability and usability.
- 19. DUPLICATE ROWS The default display of queries is all rows, including duplicate rows. Distinct or Unique keyword use to eliminate duplicate rows
- 20. DISPLAYING THE TABLE STRUCTURE #DESCRIBE command use to display the structure of a table.