+
+## Creating user
+1. ### Connect to system
+ ```
+ connect system
+ ```
+ > Then enter password
+2. ### Create user
+ ```
+ create user saeed identified by saeed;
+ ```
+ > create user user_name identified by password;
+3. ### Grant all priviledges
+ ```
+ grant all privileges to saeed;
+ ```
+4. ### Connect to the user
+ ```
+ disconnect
+ connect saeed;
+ ```
+ > Then enter password
+
+
+## Important command
+
+- ### Clear sql terminal
+ ```
+ clear screen
+ ```
+- ### Print into Sql Terminal
+ ```
+ prompt your message;
+ ```
+- ### Run .sql file
+ ```
+ start C:\Users\User\Documents\Codes\SQL\ScheduleManagement\ddl.sql
+ ```
+ > start path/filename.sql;
+- ### Set linesize
+ ```
+ show linesize
+ set linesize 100
+ ```
+- ### Set pagesize
+ ```
+ show pagesize
+ set pagesize 50
+ ```
+- ### Show all tables
+ ```
+ select table_name from user_tables;
+ ```
+- ### Show current user
+ ```
+ show user
+ ```
+- ### Show table schema
+ ```
+ describe test;
+ ```
+ > describe table_name;
+
+| FROM | +WHERE | +GROUP BY | +HAVING | +SELECT | +ORDER BY | +LIMIT | +
+
+ - ### day_schedule -client
+ 
+
+ - ### time_schedule -client
+ 
+
+ - ### notification -server
+ 
+
+- ## Read operation ?
+ - ### Integrity constraint
+ 
+
+ > Data is not being inserted beacuse user_id is foreign key to user_table and '111vH1E5iZ8o7O9MuEqW2BniUShRFq2' doesn't exist at user table.
+ - ### Displaying data with event data '05/06/2023'
+ > select, where
+ ```
+ select * from time_schedule where event_date = '05/06/2023';
+ ```
+ 
+
+ - ### Displaying date & number of schedules at that date
+ > select, where, sub-query, aggregate function, rename table, naming column
+ ```
+ select event_date, (select count(*) from time_schedule ts where ds.event_date = ts.event_date) as no_of_schedules from day_schedule ds;
+ ```
+ 
+
+ - ### Finding upcoming one schedule with date
+ > select, where, sub-query, aggregate-function, 2 tables
+ ```
+ select
+ event_date,
+ message
+ from
+ time_schedule ts
+ where
+ (
+ ts.event_date = (
+ select
+ event_date
+ from day_schedule
+ where
+ time_in_day = (
+ select
+ min(time_in_day)
+ from
+ day_schedule
+ )
+ )
+ );
+ ```
+ 
+
+
+- ## Update operation
+ - ### Updating user's name
+ > update name of a specified user
+ ```
+ update user_table set name='Md Abu Saeed' where user_id = 'a2E5iZ8o7O9MuEqW2BniUShRFq2';
+ ```
+ 
+
+- ## Delete operation
+ - ### dummy insert
+ ```
+ insert into day_schedule
+ values(
+ '27/01/2023',19368,'Saturday','Saeed','23 May at 08:16AM','i18E5iZ8o7O9MuEqW2BniUShRFq10'
+ );
+ ```
+ > 1 row created.
+
+ - ### deleting added data
+ ```
+ delete from
+ day_schedule
+ where
+ user_id = 'i18E5iZ8o7O9MuEqW2BniUShRFq10'
+ and event_date = '27/01/2023';
+ ```
+ > 1 row deleted.
+
+
+- ## union, intersect, except
+ - ### union - all date of thursday and saturday
+ ```
+ select
+ event_date,
+ day
+ from
+ day_schedule
+ where
+ day = 'Thursday'
+ union
+ select
+ event_date,
+ day
+ from
+ day_schedule
+ where
+ day = 'Saturday';
+ ```
+ > Both set must have to have same no of column and definition
+
+ 
+
+ - ### intersect - Show only Saturday
+ ```
+ select
+ event_date,
+ day
+ from
+ day_schedule
+ where
+ day in('Saturday', 'Sunday')
+ intersect
+ select
+ event_date,
+ day
+ from
+ day_schedule
+ where
+ day = 'Saturday';
+ ```
+ 
+
+ - ### except - not supported in my db
+ ```
+ select
+ event_date,
+ day
+ from
+ day_schedule
+ where
+ day in('Saturday', 'Sunday')
+ and event_date not in (
+ select
+ event_date
+ from
+ day_schedule
+ where
+ day = 'Sunday'
+ );
+ ```
+ > Except is not supported in all database version
+
+ 
+
+- ## with clause - date & number of schedules at that date
+
+ > allows to give a 'sub-query block' a name
+
+ ```
+ with my_table(n_date,total) as (
+ select
+ event_date, count(event_date)
+ from
+ time_schedule
+ group by
+ event_date
+ )
+ select
+ event_date,
+ total
+ from
+ day_schedule ,
+ my_table
+ where
+ event_date = n_date;
+ ```
+ 
+
+
+
+- ## Aggregate function
+ - ### AVG
+ ```
+ select avg(time_in_day) as avg from day_schedule;
+ ```
+ - ### COUNT
+ ```
+ select event_date, count(*) as total from time_schedule group by event_date;
+ ```
+ > shows date with schedule count
+ - ### MAX
+ ```
+ select event_date from time_schedule where timestamp_utc = ( select max(timestamp_utc) from time_schedule);
+ ```
+ > shows last schedule date
+ - ### MIN
+ ```
+ select event_date from time_schedule where timestamp_utc = ( select min(timestamp_utc) from time_schedule);
+ ```
+ > shows first schedule date
+ - ### SUM
+ ```
+ select sum(is_completed) completed, count(*) - sum(is_completed) incomplete from time_schedule;
+ ```
+ > shows number of completed nad incomplete schedules
+
+- ## Group by and Having
+ ```
+ select event_date, count(*) from time_schedule group by event_date having count(*) > 1;
+ ```
+ > Date with more than 1 schedules
+
+ 
+
+
+
+- ## Set membership operation(and,or,not)
+ ```
+ select
+ user_id,
+ message_new
+ from
+ notification
+ where
+ (
+ user_id = 'vH1E5iZ8o7O9MuEqW2BniUShRFq2'
+ or user_id = 'vH1E5iZ8o7O9MuEqW2BniUShRFq1'
+ )
+ and is_completed = 0;
+ ```
+ > all incomplete schedules of two user
+
+ 
+
+- ## some/all/exists/unique
+ - ### some
+ ```
+ select
+ event_date,
+ message
+ from
+ time_schedule
+ where
+ ts_midnight <= some(
+ select
+ ts_midnight
+ from
+ time_schedule
+ where
+ ts_midnight <= 735
+ );
+ ```
+ > All user's schedules before 12:16PM
+
+ 
+ - ### all
+ ```
+ select
+ event_date,
+ message
+ from
+ time_schedule
+ where
+ ts_midnight <= all(
+ select
+ ts_midnight
+ from
+ time_schedule
+ where
+ ts_midnight >= 735
+ );
+ ```
+ > All user's schedules before 12:16PM
+
+ 
+ - ### exists
+ ```
+ select
+ name
+ from
+ user_table ut
+ where
+ exists(
+ select
+ *
+ from
+ notification
+ where
+ user_id = ut.user_id
+ );
+ ```
+ > All user's who has notification
+
+ 
+
+
+- ## String operation
+ > percent ( % ). The % character matches any substring
+
+ > underscore ( _ ). The _ character matches any character
+
+ - ### name having length 5
+ ```
+ select name from user_table where name like '_____';
+ ```
+ 
+ - ### name ends with h
+ ```
+ select name from user_table where name like '%h';
+ ```
+ 
+ - ### name containing e
+ ```
+ select name from user_table where name like '%e%';
+ ```
+ 
+- ## Join
+ - ### natural join
+ ```
+ select
+ user_id,
+ event_date,
+ message
+ from
+ day_schedule natural
+ join time_schedule
+ where
+ user_id = 'vH1E5iZ8o7O9MuEqW2BniUShRFq2';
+ ```
+ 
+
+ 
+
+ - ### Left outer join
+ ```
+ select user_id,name,event_date from user_table left outer join day_schedule using(user_id);
+ ```
+ 
+ - ### Right outer join
+ ```
+ select user_id,name,event_date from user_table right outer join day_schedule using(user_id);
+ ```
+ 
+ - ### Full outer join
+ ```
+ select user_id,name,event_date from user_table full outer join day_schedule using(user_id);
+ ```
+ 
+
+
+- ## Views
+ > view is a virtual table derived from the result of a query that can be treated a table. Views are useful for simplifying complex queries.
+
+ - ### Creating view
+ ```
+ create view my_view as select ts_midnight from time_schedule where ts_midnight >= 735;
+ ```
+ - ### using that view
+ ```
+ select event_date, message from time_schedule where ts_midnight <= all(select * from my_view);
+ ```
+
+
+ - ### Dropping that view
+ ```
+ drop view my_view;
+ ```
+
+
+- ## Set values and insert
+ ```
+ set serveroutput on
+ declare
+ uid USER_TABLE.USER_ID%type := 'abcdef1234';
+ email varchar(30) := 'abutest3456@gmail.com';
+ name varchar(30) := 'A Saeed';
+ password user_table.password%type := '123456';
+ begin
+ delete from user_table where user_id = 'abcdef1234';
+
+ -- main line of code
+ insert into user_table values(uid,email,name,password);
+
+ select * into uid, name, email, password from user_table where user_id = 'abcdef1234';
+
+ dbms_output.put_line(uid || ' ' || name || ' ' || email || ' ' || password);
+ end;
+ /
+ ```
+ 
+- ## RowType
+ > A data type that represents a row in a table.
+ ```
+ set serveroutput on
+ declare
+ my_row user_table%rowtype;
+ begin
+ select * into my_row from user_table where user_id = 'abcdef1234';
+ dbms_output.put_line(my_row.user_id || ' ' || my_row.email);
+ end;
+ /
+ ```
+ 
+
+- ## Cursor and Loop
+ > A pointer to a set of rows returned by a SELECT query
+ ```
+ set serveroutput on
+ declare
+ cursor cur is select * from user_table;
+ row user_table%rowtype;
+
+ begin
+ open cur;
+ fetch cur into row;
+
+ while cur % found loop
+ dbms_output.put_line(row.user_id || ' ' || row.name);
+ fetch cur into row;
+ end loop;
+
+ close cur;
+ end;
+ /
+ ```
+ 
+
+- ## Array and for loop
+ - ### Declaring type
+ ```
+ TYPE NAME_ARR IS VARRAY(5) OF user_table.name%type;
+ ```
+ > It defines a user-defined collection type named NAME_ARR as a variable array of 5 elements. where each element is of type name in user_table
+
+ - ### Creating variable
+ ```
+ arr NAME_ARR := NAME_ARR();
+ ```
+ > above line of code will initialize an array variable whose elements type is same as name of user_table.
+
+ - ### with extend() function
+ ```
+ set serveroutput on
+ declare
+ type NAME_ARR is VARRAY(5) of user_table.name%type;
+ arr NAME_ARR := NAME_ARR();
+ counter number;
+
+ begin
+ counter := 1;
+ for i in 13..15
+ loop
+ arr.extend();
+ arr(counter) := 'abu ' || i;
+ counter := counter+1;
+ end loop;
+
+ dbms_output.put_line('------------------------------------------------');
+
+ counter := 1;
+ while (counter <= arr.count )
+ loop
+ dbms_output.put_line(arr(counter));
+ counter := counter+1;
+ end loop;
+
+ end;
+ /
+ ```
+
+ 
+
+ - ### without extend() function
+ ```
+ set serveroutput on;
+
+ declare
+ TYPE ID_ARRAY is VARRAY(5) of USER_TABLE.USER_ID % type;
+
+ uids ID_ARRAY := ID_ARRAY('vH1E5iZ8o7O9MuEqW2BniUShRFq2','c12E5iZ8o7O9MuEqW2BniUShRFq4','g16E5iZ8o7O9MuEqW2BniUShRFq8');
+
+ uid USER_TABLE.USER_ID%type;
+ name user_table.name%type;
+
+ begin
+ for i in 1..uids.count loop
+ select user_id, name into uid, name from user_table where user_id = uids(i);
+ dbms_output.put_line(uid || ' -> ' || name);
+ end loop;
+ end;
+ /
+ ```
+ 
+
+ - ### extend() vs without extend()
+ | with | +without | +
| increase size dynamically by one | +size is defined manually | +
| need to extend before adding | +can assign directly | +
+
+ - ### Procedure
+ - Creating procedure
+ ```
+ create or replace procedure printUserInfo(uid IN varchar, row OUT user_table%rowtype) as
+ tmp varchar(30);
+ begin
+ select * into row from user_table where user_table.user_id = uid;
+
+ tmp := row.name;
+ dbms_output.put_line(tmp);
+ end;
+ /
+ ```
+ > after executing..
+
+ 
+ - Calling procedure
+ ```
+ set serveroutput on
+
+ declare
+ val user_table%rowtype;
+ uid varchar(30) := 'vH1E5iZ8o7O9MuEqW2BniUShRFq2';
+ begin
+ printUserInfo(uid,val);
+ dbms_output.put_line(val.user_id || ' ' || val.name);
+ end;
+ /
+ ```
+ 
+ - Drop procedure
+ ```
+ drop procedure printUserInfo;
+ ```
+ > drop procedure procedure_name;
+
+ - ### Function
+ - Creating function
+ ```
+ create or replace function getName(uid in varchar) return varchar as
+ name varchar(30);
+ begin
+ select user_table.name into name from user_table where user_table.user_id = uid;
+
+ dbms_output.put_line('returning ' || name);
+ return name;
+ end;
+ /
+ ```
+ - Calling function
+
+ ```
+ set serveroutput on
+
+ declare
+ val varchar(30);
+ uid varchar(30) := 'vH1E5iZ8o7O9MuEqW2BniUShRFq2';
+ begin
+ val := getName(uid);
+ dbms_output.put_line(val);
+ end;
+ /
+ ```
+
+ 
+ - Drop function
+ ```
+ drop function getName;
+ ```
+ > drop function function_name;
+
+
+ - ### procedure vs function
+ | Procedure | +Function | +
| Can't return value | +Can return value | +
| + cannot be directly used in SQL statement. + | +Can be used in SQL statements directly | +