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06/03/2024 ===================================================================================================== Update statement: the update statement is used for modify the existing records. syntax:-update tablename set column_name=values where condition. use testdb; select * from person; update person set age=35 where p_id=4; update person set age =24 Note: If you omit the where clause all records in the table will be updated. ================================================================================================ differance alter and update: alter:1. data defination lang(DDL) 2.alter command will perform structure level. 3.syntax alter table tablename (modify/add/rename) Drop column column_name 4. this command make changes with the table structure. 5. alter command works on columns update:1. data manipulation lang(DML) 2.update command will perform on data level. 3 syntax :-update table_name set column_name=values 4. this command make changes the data inside table. 5. update cammand works on perticular rows in the table =============================================================================================== Delete statement:- delete statement is use for delete the existing records in the table . syntax:-delete from tablename where condition exa:- delete from pesron where Pname="tina" ------------------------------------------------------------------ difference between truncate and delete delete:-1. It is DML command 2.delete command is use where clause. 3.delete operations can be rolled back 4.delete command is slower than truncate command. 5. the delete command is used to delete the specific rows(as per condition) truncate:-1. It is DDL command 2. In truncate command we are not use where clause 3. truncate can not be rolled back 4. truncate command is faster than delete command 5. truncte command is used to delete all rows from the table. Note: If you omit the where clause all records in the table will be deleted. ========================================================================================================= commit and rollback commit :- commiot in sql is used for permanantly save the changes. rollback: rollback command is used for undo the trasactional data that have not saved in the database. select * from customerinfo; update customerinfo set addr="pune" where cust_id=101; commit; update customerinfo set addr="nanded" where cust_id=104; update customerinfo set addr="mumbai" where cust_id=106; rollback; select * from customerinfo; delete from customerinfo ; rollback; truncate table customerinfo; rollback; ========================================================================================================================= assignment:- Q1.From the following table, write a SQL query to find the maximum order (purchase) amount for each customer. The customer ID should be in the range 3002 and 3007(Begin and end values are included.). Filter the rows for maximum order (purchase) amount is higher than 1000. Return customer id and maximum purchase amount. Sample table: orders ord_no purch_amt ord_date customer_id salesman_id ---------- ---------- ---------- ----------- ----------- 70001 150.5 2012-10-05 3005 5002 70009 270.65 2012-09-10 3001 5005 70002 65.26 2012-10-05 3002 5001 70004 110.5 2012-08-17 3009 5003 70007 948.5 2012-09-10 3005 5002 70005 2400.6 2012-07-27 3007 5001 70008 5760 2012-09-10 3002 5001 70010 1983.43 2012-10-10 3004 5006 70003 2480.4 2012-10-10 3009 5003 70012 250.45 2012-06-27 3008 5002 70011 75.29 2012-08-17 3003 5007 70013 3045.6 2012-04-25 3002 5001
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