176 lines
No EOL
4.5 KiB
Markdown
176 lines
No EOL
4.5 KiB
Markdown
## Week 7 - DBMS Lab - PL SQL & Triggers
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### Q1. Generate a trigger displaying driver information, on participating in an accident.
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Trigger:
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```sql
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CREATE OR REPLACE TRIGGER trg_display_driver_info
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AFTER INSERT ON participated
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FOR EACH ROW
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DECLARE
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v_driver_name VARCHAR2(100);
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v_driver_address VARCHAR2(255);
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BEGIN
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SELECT NAME, ADDRESS
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INTO v_driver_name, v_driver_address
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FROM person
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WHERE DRIVER_ID# = :NEW.DRIVER_ID#;
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DBMS_OUTPUT.PUT_LINE('Driver ID: ' || :NEW.DRIVER_ID#);
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DBMS_OUTPUT.PUT_LINE('Driver Name: ' || v_driver_name);
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DBMS_OUTPUT.PUT_LINE('Driver Address: ' || v_driver_address);
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DBMS_OUTPUT.PUT_LINE('Car Registration Number: ' || :NEW.REGNO);
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DBMS_OUTPUT.PUT_LINE('Report Number: ' || :NEW.REPORT_NUMBER);
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DBMS_OUTPUT.PUT_LINE('Damage Amount: ' || :NEW.DAMAGE_AMOUNT);
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END;
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/
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```
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Demo:
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```sql
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SQL> INSERT INTO participated (DRIVER_ID#, REGNO, REPORT_NUMBER, DAMAGE_AMOUNT)
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2 VALUES (1235, 'EFGH2001', 3, 5000);
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Driver ID: 1235
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Driver Name: Rohit
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Driver Address: Banglalore India
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Car Registration Number: EFGH2001
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Report Number: 3
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Damage Amount: 5000
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Driver_id: 1235 Name: Rohit Address: Banglalore India
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1 row created.
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```
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### Q2. Create a trigger that updates a `total_damage` column in the `accident` table whenever a new entry is added to or removed from the participated field.`
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Trigger:
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```SQL
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SQL> CREATE OR REPLACE TRIGGER update_total_damage
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2 AFTER
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3 INSERT OR DELETE ON PARTICIPATED
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4 BEGIN
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5 UPDATE ACCIDENT
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6 SET
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7 total_damage = (
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8 SELECT
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9 SUM(damage_amount)
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10 FROM PARTICIPATED p
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11 WHERE
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12 p.report_number = ACCIDENT.report_number
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13 );
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14 END;
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15 /
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Trigger created.
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```
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Adding an identifier `total_damage`:
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```sql
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SQL> ALTER TABLE ACCIDENT ADD total_damage NUMBER;
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```
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Test case with Insertion:
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```sql
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SQL> INSERT INTO
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PARTICIPATED (driver_id#, regno, report_number, damage_amount)
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VALUES
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('1235', 'EFGH2001', 1, 5000);
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Driver_id: 1235 Name: Rohit Address: Banglalore India
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1 row created.
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SQL> SELECT
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report_number,
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total_damage
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FROM ACCIDENT
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WHERE
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report_number = 1;
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REPORT_NUMBER TOTAL_DAMAGE
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------------- ------------
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1 15000
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```
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Test case with Deletion:
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```sql
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SQL> DELETE FROM PARTICIPATED
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WHERE
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driver_id# = '1235'
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AND regno = 'EFGH2001'
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AND report_number = 1;
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1 row deleted.
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SQL> SELECT
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report_number,
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total_damage
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FROM ACCIDENT
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WHERE
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report_number = 1;
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REPORT_NUMBER TOTAL_DAMAGE
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------------- ------------
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1 10000
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```
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### Q3. List cars involved in accidents with cumulative damage exceeding a specific amount.
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Checking for damage amount > 10000, we have
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```SQL
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SQL> SELECT
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p.driver_id#,
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o.regno,
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SUM(pa.damage_amount) AS total_damage
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FROM
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PARTICIPATED pa
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JOIN
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OWNS o ON pa.driver_id# = o.driver_id#
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JOIN
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PERSON p ON o.driver_id# = p.driver_id#
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GROUP BY
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p.driver_id#, o.regno
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HAVING
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SUM(pa.damage_amount) > 10000;
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DRIVER_ID# REGNO TOTAL_DAMAGE
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------------------------------ -------------------- ------------
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1238 HFSP5601 26500
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```
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### Q4. Identify cars that have been involved in more than one accident and calculate the total damage for each car.
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```SQL
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SQL> SELECT
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o.regno,
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COUNT(DISTINCT pa.report_number) AS accident_count,
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SUM(pa.damage_amount) AS total_damage
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FROM
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PARTICIPATED pa
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JOIN
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OWNS o ON pa.driver_id# = o.driver_id#
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GROUP BY
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o.regno
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HAVING
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COUNT(DISTINCT pa.report_number) > 1;
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REGNO ACCIDENT_COUNT TOTAL_DAMAGE
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-------------------- -------------- ------------
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HFSP5601 2 26500
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```
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### Q5. Calculate the average damage amount for accidents at each location.
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```sql
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SQL> SELECT
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a.location,
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AVG(pa.damage_amount) AS average_damage
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FROM
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ACCIDENT a
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JOIN
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PARTICIPATED pa ON a.report_number = pa.report_number
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GROUP BY
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a.location;
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LOCATION AVERAGE_DAMAGE
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-------------------------------------------------- --------------
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karnataka India 25000
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Delhi India 10000
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India 2575
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Gujrat India 1500
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``` |