Question

Please help we are suppose to explain what the C code does.

This is the electronics database

(6 pts) This problem is based on Electronics database. Add some annotations to the following table to explain what the C program is doing in detail. Note that "void" is how C declares a function that does not return anything. You are expected to generalize or research svntaxes not mentioned in the lecture C Program Annotation void newPCproduct EXEC SQL BEGIN DECLARE SECTION; char pmaker, pmodelt4], ptypel6 float pspeed; int pram, phd, pprice,; int pcount; EXEC SQL END DECLARE SECTION; EXEC SQL PREPARE stmt1 FROM SELECT COUNT() INTO :count FROM PC WHERE MODEL = ?; EXEC SQL PREPARE stmt2 FROM INSERT INTO Product VALUES (?, ?, ?)'; EXEC SQL PREPARE stmt 3 FROM INSERT INTO PC VALUES(?, ?, ?, ?,?)'; prompt ("Enter manufacturer: ", pmaker) prompt ("Enter model: ", pmodel) prompt ("Enter type: ", ptype) prompt ("Enter speed:", pspeed) prompt ("Enter ram: ", pram) i prompt ("Enter hard-disk: ", phd) prompt ("Enter price: ", pprice) EXEC SQL EXECUTE stmt1 USING:pmodel; IF (count >0) Printf ("Warnning: The PC model already exists n") ELSE EXEC SQL EXECUTE stmt2 USING pmaker, :pmodel, :ptype; EXEC SQL EXECUTE stmt3 UINGNG pmodel, :pspeed, :pram, :phd, :pprice 5 USE Electronics; CREATE TABLE Product( 7 8 maker CHAR (1), model CHAR (4) 10 type VARCHAR(10), PRIMARY KEY (model) 12 13 14 CREATE TABLE PC ( 15 model CHAR (4), 16 speed NUMERIC (3,2), 17 ram INT 18 hd INT 19 price NUMERIC, 20 PRIMARY KEY (model), 21 FOREIGN KEY (model) REFERENCES Product (model) 23 24 CREATE TABLE Laptop( model CHAR (4) 25 speed NUMERIC (3,2) 26 27 ram INT 28 hd INT 29 screen NUMERIC(3,1), 30 price NUMERIC, 31 PRIMARY KEY (model), FOREIGN KEY (model) REFERENCES Product (model) 32 34 35CREATE TABLE Printer( model CHAR (4), 36 color BOOL, 37 38 type VARCHAR (10), 39 price NUMERIC, 40 PRIMARY KEY (model), 41 FOREIGN KEY (model) REFERENCES Product(model) 42 INSERT INTO Product VALUES ("A· '1001', 'pc' ); 44 45 # INSERT INTO Product VALUES(' A', '1002. pc' ); 46 # INSERT INTO Product VALUES ('A', '1003', 'pc' ); 47 # INSERT INTO Product VALUES ('A', '2004', 'laptop'); 48 # INSERT INTO Product VALUES('A', '2005', 'laptop'); 49 # INSERT INTO Product VALUES ('A', '2006', 'laptop'); 50 INSERT INTO Product VALUES ('B· '1004', ' pc' ); 51 INSERT INTO Product VALUES ('B· '1005', 'pc' ); 52 # INSERT INTO Product VALUES('B', '1006', 'pc' ); 53 # INSERT INTO Product VALUES ('B', '2007· 'laptop'); 54 # INSERT INTO Product VALUES('C', '1007', 'pc'); 55 # INSERT INTO Product VALUES ('D. '1008', 'pc'); 56 # INSERT INTO Product VALUES ("D. '1009", "pc' ); 57 # INSERT INTO Product VALUES ("D· '1010', 'pc'); 58 INSERT INTO Product VALUES ("D', '3004', 'printer'); 59 # INSERT INTO Product VALUES ('D· '3005', 'printer'); INSERT INTO Product VALUES('E', '1011', 'pc' ); 60 # 61 # INSERT INTO Product VALUES ('E', '1012', 'pc' ); 62 INSERT INTO Product VALUES(' E', '1013', 'pc' ); 63 INSERT INTO Product VALUES ('E· '2001', 'laptop'); 64 # INSERT INTO Product VALUES('E', '2002', 'laptop'); 65 # INSERT INTO Product VALUES(' E', '2003', 'laptop'); 66 # INSERT INTO Product VALUES('E', '3001', 'printer'); 67 # INSERT INTO Product VALUES('E', '3002', 'printer'); 68 # INSERT INTO Product VALUES('E', '3003', 'printer'); 69 # INSERT INTO Product VALUES ('F', '2008· 'laptop'); 70 # INSERT INTO Product VALUES('F', '2009, 'laptop'); 71 INSERT INTO Product VALUES ('G', '2010', 'laptop'); 72 # INSERT INTO Product VALUES('H', '3006', 'printer'); 73 # INSERT INTO Product VALUES ('H· '3007', 'printer'); 74 75 # INSERT INTO PC VALUES('1001., 2.66, 1024, 250, 2114); 76INSERT INTO PC VALUES ('1002, 2.10, 512, 250, 995); 77 # INSERT INTO PC VALUES ('1003', 1.42, 512, 80, 478); 78 # INSERT INTO PC VALUES('1004. 2.80, 1024, 250, 649); INSERT INTO PC VALUES ('1005', 3.20, 512, 250, 630); 79 # 80 # INSERT INTO PC VALUES ('1006', 3.20, 1024, 320, 1049); 81 # INSERT INTO PC VALUES ('1007. 2.20, 1024, 200 , 510); 80 # INSERT INTO PC VALUES ('1006', 3.20, 1024, 320, 1049); 81 # INSERT INTO PC VALUES('1007. 2.20, 1024, 200, 510); 82 INSERT INTO PC VALUES('1008. 2.20, 2048, 250, 770); 83 # INSERT INTO PC VALUES ('1009", 2.00, 1024, 250, 650); 84 # INSERT INTO PC VALUES('1010', 2.80, 2048, 300, 770); 85 # INSERT INTO PC VALUES('1011', 1.86, 2048, 160, 959); 86 INSERT INTO PC VALUES('10 12. 2. 80, 1024, 160, 649); 87 INSERT INTO PC VALUES('1013. 3.06, 512, 80, 529); 89INSERT INTO Laptop VALUES(2001', 2.00, 2048, 240, 20.1, : 90 # INSERT INTO Laptop VALUES ('2002. 1.73, 1024, 80, 17.0, 9 91 # INSERT INTO Laptop VALUES ('2003', 1.80, 512, 60 , 15.4, 54 92 # INSERT INTO Laptop VALUES ('2004, 2.00, 512, 60, 13.3, 115 93 # INSERT INTO Laptop VALUES('2005. 2.16, 1024, 120, 17.0 94 INSERT INTO Laptop VALUES ('2006', 2.00, 2048, 80, 15.4, 1: 95 # INSERT INTO Laptop VALUES('2007. 1.83, 1024, 120, 13.3, 96 INSERT INTO Laptop VALUES ('2008", 1.60, 1024, 100, 15.4, 97 # INSERT INTO Laptop VALUES ("2009", 1.60, 512, 80, 14.1, 686 98 # INSERT INTO Laptop VALUES ('2010', 2.00, 2048, 160, 15.4 100 INSERT INTO Printer VALUES ('3001', true, 'int-jet', 99); INSERT INTO Printer VALUES ('3002', false, 'laser', 239); 101 # 102INSERT INTO Printer VALUES (3003', true, 'laser', 899); 103 # INSERT INTO Printer VALUES('3004. .int-jet', 120); true, 104 # INSERT INTO Printer VALUES ('3005', false, 'laser', 120); 105 # INSERT INTO Printer VALUES ('3006', true, 'int-jet', 100); 106 INSERT INTO Printer VALUES ('3007. true, 'laser', 200); 107 108 109 110 112 113 114 115 116

Answer 1

The are many sections in the code to understand.

In the first section,

from EXEC SQL BEGIN DECLARE SECTION to EXEC SQL END DECLARE SECTION

we define the variables which will be used in the SQL query.

pmaker is will contain a single character, pmodel, which is a string, can contain at most 4 characters. ptype, which is a string, can contain at most 6 characters. pspeed is a floating point number. pram, phd, pprice, pcount are integers.

Now in the next section, we prepare a statement stmt1,

the is ? in the statement which specifies that this is a placeholder (its value will be provided at the time of query execution). The stmt1 query will count the number of PCs of given model and store the result into count variable.

Now next section create a statement stmt2 which is a query to store an entry into table Product. (all three ? are placeholder and their values need to be provided at the time of query execution.)

And next section create a statement stmt3 which is a query to store an entry into table PC.(all five ? are placeholder and their values need to be provided at the time of query execution.)

Now next few line (prompt) ask the user the inputs.

And then the line,

EXEC SQL EXECUTE stmt1 USING : pmodel;

will execute the query stmt1, which returns the count of PCs using model provided by user. (the result will be stored in count variable).

then we are checking that if (count>0) means there are some PCs of the given model, in this case show a use a warning message.

on other case,

execute the stmt2 query , which will first insert a product into the table Product with the values provided by user.

and then insert an entry into PC table with the value pmodel, pspeed, pram, phd, pprice which are the values provided by user.