Study notes 22/1/18

Learning notes

One 、 Block code

1. conditional （if else）

• Grammatical structure

IF   Conditions 1 THEN 
		     operation 1;
		  ELSIF  Conditions 2 THEN
				 operation 2;
			ELSIF  Conditions 3 THEN 
				 operation 3;
				...
		  ELSE  operation N;
		END IF;	

eg： Pass in an employee's job number if the employee's The position is ANALYST perhaps CLERK perhaps SALESMAN Just give the staff 500 Block salary if the employee's Position MANAGER , Just give the staff 800 Block salary if it is PRESIDENT , Don't worry , Do nothing ;

CREATE TABLE EMP_7521 AS SELECT * FROM EMP;
--  Create a new table , prevent emp The data in the table has been changed 

DECLARE 
  V_ENO EMP_7521.EMPNO%TYPE := 7521;
  V_JOB EMP_7521.JOB%TYPE; 
	
BEGIN 
  SELECT E.JOB
	INTO V_JOB
	FROM EMP_7521 E
	WHERE E.EMPNO = V_ENO;
	
	
	IF V_JOB IN('ANALYST' , 'LERK' , 'SALESMAN') THEN
		       UPDATE EMP_7521 E SET E.SAL = E.SAL + 500
					 WHERE E.EMPNO = V_ENO;
	ELSIF V_JOB = 'MANAGER' THEN 
		       UPDATE EMP_7521 E SET E.SAL = E.SAL + 500
					 WHERE E.EMPNO = V_ENO;
	END IF;              
	
	/* CASE WHEN V_JOB IN('ANALYST' , 'LERK' , 'SALESMAN') THEN UPDATE EMP_7521 E SET E.SAL = E.SAL + 500 WHERE E.EMPNO = V_ENO; WHEN V_JOB = 'MANAGER' THEN UPDATE EMP_7521 E SET E.SAL = E.SAL + 500 WHERE E.EMPNO = V_ENO; END CASE; */   
	-- CASE WHEN  It can do the same thing 
	
	COMMIT;

END;

SELECT * FROM EMP_7521;       --  Used to view the modified table 

2.if else Nesting of clauses

There's nothing to say in this part , It's just a set in a set and it's over .

3. loop

(1)for loop

Grammatical structure ：

FOR  Loop variable  IN  Cycle lower limit .. Cycle upper limit  LOOP  
	-- Loop variables can use any letter or word 
          The loop body （ Logic to repeat ） 
END LOOP;

eg： Calculation 1 To 10 The cumulative value of an even number in a number ;

DECLARE
  V_SUM NUMBER := 0;

BEGIN 
	FOR I IN 1..10 LOOP 
		IF MOD(I,2) = 0 THEN 
			V_SUM := V_SUM + I;
			DBMS_OUTPUT.put_line(V_SUM);
		END IF;
		END LOOP;
		
	DBMS_OUTPUT.put_line(' Cumulative value ：'||V_SUM);	
		
END;  

PS： There is a problem in the above question , I found the = As the difference between assignment and comparison , When = For comparison , It is used alone or added later any、all Other key words , But when it is used for assignment , You have to use ：= Assign values to the style of , Use it directly = Assignment in PLSQL It's not allowed in ;

（2）loop loop

Grammatical structure ：

LOOP 
    The loop body ;
	 
	 -- EXIT  Exit circular keyword 
	 /*IF  Exit conditions  THEN EXIT;*/
	 EXIT WHEN  Exit conditions ;
END LOOP;

eg： Calculation 1 To 10 The cumulative value of (LOOP loop );

DECLARE 
 V_SUM NUMBER := 0;
 V_I NUMBER := 1;

BEGIN 
	LOOP 
		V_SUM := V_SUM + V_I;
		/*IF V_I = 10 THEN EXIT; END IF;*/	
		--  use  if  Statement exit loop loop 
		EXIT WHEN V_I = 10;
		V_I := V_I + 1;
	END LOOP;	
	
	DBMS_OUTPUT.put_line(V_SUM);

END;

eg： Calculation 1 To 10 The cumulative value of an even number in a number (LOOP loop );

DECLARE
 V_SUM NUMBER := 0;
 V_I   NUMBER := 1;

BEGIN
	LOOP
		
		IF MOD(V_I,2) = 0 THEN 
			V_SUM := V_SUM + V_I;
		END IF;
		EXIT WHEN V_I = 10;
		V_I := V_I + 1; 
	
	END LOOP;
	
	DBMS_OUTPUT.put_line(V_SUM);

END;

（3）while loop

Grammatical structure ：

WHILE  Conditions for entering the cycle  LOOP 
	   The loop body ;
END LOOP;

eg： Calculation 1 To 10 The cumulative value of (while loop );

DECLARE 
     V_SUM NUMBER := 0;
		 V_I   NUMBER := 1;

BEGIN
	WHILE V_I <= 10 LOOP
		V_SUM := V_SUM + V_I;
		V_I := V_I + 1;
	END LOOP;
	
	DBMS_OUTPUT.put_line(V_SUM);

END;  

eg： Calculation 1 To 10 The cumulative value of an even number in a number (while loop );

DECLARE 
     V_SUM NUMBER := 0;
		 V_I   NUMBER := 1;

BEGIN 
	WHILE V_I <= 10 LOOP
		 IF MOD(V_I,2) = 0 THEN
			 V_SUM := V_SUM + V_I;
		 END IF;
		 V_I := V_I + 1;
	END LOOP;
	
	DBMS_OUTPUT.put_line(V_SUM);

END; 

eg; Calculation 1 To 100 The cumulative value of prime numbers of ;

DECLARE 
     V_SUM NUMBER := 0;       --  Prime and 
		 V_POW NUMBER;            --  Radical v_i, Used as a judgment condition 
		 V_I   NUMBER := 2;       --  from 1~100 Count variables for 
		 V_J   NUMBER := 2;       --  from 2~v_pow Count variables for 
		 V_FLAG NUMBER := 0;      --  Whether it is a prime number 

BEGIN
	LOOP 
		V_POW := POWER(V_I,0.5);
		
		WHILE V_J <= V_POW LOOP      -- V_J  Should be less than v_i Square root 
			IF MOD(V_I,V_J) = 0 THEN 
				V_FLAG := 1;
				EXIT;           --  If you can divide , Not primes ,flag Set up 1, Exit inner loop 
			END IF;
			V_J := V_J + 1;    --  If it's not divisible ,v_j Cycle after self increase 
		END LOOP;
		
		V_J := 2;      --  Prepare for the next cycle 
		
		IF V_FLAG = 0 THEN
			V_SUM := V_SUM + V_I;
			DBMS_OUTPUT.put_line(V_SUM);
			DBMS_OUTPUT.put_line(V_I);
			DBMS_OUTPUT.put_line('----------------------');
			--  If v_flag zero , It's prime number , Add to v_sum In the middle 
			
		ELSE V_FLAG := 0;   --  If not zero  , take flag Zeroing 
		END IF; 
		
		V_I := V_I + 1;
		
		EXIT WHEN V_I > 100;
	  
	END LOOP;

  DBMS_OUTPUT.put_line('0~100 The sum of prime numbers of is ：'||V_SUM);
END;  

SELECT POWER(4,0.5)
FROM DUAL;

• There is still a problem with this question , But I really don't understand , Why, logically 4 Obviously will not be added , But it will be judged as a prime number for accumulation ;

eg： multiplication table ;

DECLARE 
   V_MUL NUMBER;
	 V_I NUMBER := 1;
	 V_J NUMBER := 1;

BEGIN
	WHILE V_I <= 9 LOOP 
		V_J := 1;
		WHILE V_J <= V_I LOOP
			V_MUL := V_I * V_J;
			DBMS_OUTPUT.put(V_J||'*'||V_I||'='||V_MUL||'|');
			V_J := V_J + 1;
		END LOOP;
		DBMS_OUTPUT.put_line(' ');
	  
		V_I := V_I + 1;
	END LOOP;
	
END;  

Finishing work , The king of the new season , Go back to the glory of the king .