Differences between oracle and SQL (common functions) (2) _ MySQL

Differences between oracle and SQL (common functions) (2) ORACLE functions

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Value from dual; 1

8. use 10 as the base logarithm.

S: select log10 (10) value 1

O: select log (10, 10) value from dual; 1

9. Square

S: select SQUARE (4) value 16

O: select power (4, 2) value from dual 16

10. take the square root

S: select SQRT (4) value 2

O: select SQRT (4) value from dual 2

11. Evaluate the power S of an arbitrary number: select power (3,4) value 81 O: select power (3,4) value from dual 81

12. Random number acquisition

S: select rand () value

O: select sys. dbms_random.value (0, 1) value from dual;

13. get the symbol

S: select sign (-8) value-1

O: select sign (-8) value from dual-1
---------- Trigonometric function correlation
14. circumference rate S: select pi () value 3.1415926535897931

O: unknown

15. sin, cos, and tan parameters are in radians.

For example, select sin (PI ()/2) value to get 1 (SQLServer)

16. Asin, Acos, Atan, Atan2 return radians

17. radian angle interchange (, Oracle unknown)

DEGREES: Radian-> angle

RADIANS: Angle-> Radian

--------- Comparison of values

18. calculate the maximum value of the set

S: select max (value) value from

(Select 1 value

Union

Select-2 value

Union

Select 4 value

Union

Select 3 value)

O: select greatest (1,-2, 4, 3) value from dual

19. minimum value of the set

S: select min (value) value from

(Select 1 value

Union

Select-2 value

Union

Select 4 value

Union

Select 3 value)

O: select least (1,-2, 4, 3) value from dual

20. how to handle the null value (null in F2 is replaced by 10) S: select F1, IsNull (F2, 10) value from Tbl O: select F1, nvl (F2, 10) value from Tbl

-------- String functions

21. search for the character serial number

S: select ascii ('A') value

O: select ascii ('A') value from dual

22. calculate characters from the serial number

S: select char (97) value

O: select chr (97) value from dual

23. connection

S: select '11' + '22' + '33' value

O: select CONCAT ('11', '22') | 33 value from dual

23. substring location -- returns 3 S: select CHARINDEX ('s', 'sdsq', 2) value O: select INSTR ('sdsq', 'S', 2) value from dual

23. position of the fuzzy substring -- 2 is returned. If % is removed from the parameter, 7 is returned //

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