This document discusses various SQL commands used in SQL Plus including creating a table, altering table columns, inserting records, retrieving data using queries, joining tables, and aggregating data using group by and having clauses. It provides examples of creating a PERSONS table, modifying columns, inserting sample data, querying for highest, lowest, and average salaries, demonstrating inner joins between tables, and using group by with aggregate functions to retrieve statistics grouped by customer.

1. SQL Commands executed in
SQL Plus
Sunil Kumar Gunasekaran

2. Creating table PERSONS1013 with the following Attribute names
Altering the Column name of the table P_ID to include NOT NULL and PRIMARY
KEY status
Adding another column SALARY with data type as Number;
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3. After all the modifications done to the table
Sample of records into the table using INSERT command
Inse
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4. The table with the values loaded is shown below
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5. Getting the details of the record having the highest salary
Getting the name of the person with the highest salary
Getting the name of the person with minimum salary
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6. Getting the names of persons with salary greater than the average salary
The nested statements are used when there is one to one relationship between
person and salary.
Need to work out on Inner Join Outer Join and Natural Join and other functions and update here to be
done or revised before any interview.
Dropping the whole table using DROP DDL command
Deleting a particular record
Using Group by with a function to group by the entities based on the function;
Note that only Sum and average require group by since
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7. This is the Orders table for the above GROUP BY function execution.
The requirement is that there need to be a customer and many orders placed by him and hence many
orderprices. If we want info of the max min avg sum of the orderprices placed by each customer, then
use group by along with the functions.
Usage of Having
Having and group by are used in one t omany relationship between customer and orderprice
This is similar to where only that the aggregate functions can be used in having and aggregate functions
cannot be used in where.
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8. Note that the having can hold expressions involving aggregate functions
INNER JOIN
There are two tables. Table 1 having customer firstr name last name address and city and P_ID;
The second table has details of order i.eorderid, order number and P_ID.
We need customer first name and customer last name and the order number of customers who made
orders present in the Persons table. Hence we use inner join for this.
JOINS
Consider the following Persons table and Orders table. They have in common PID
Customer Table has PIDs 1 2 and 3
Orders Table has PIDs 3 3 1 1 and 15
We are going to make a join based on this common key.
When the join is made, a appended table containing all the column headings appear.
PID LN FN Add City O_IdONumber PID
First the common elements are filled in the above table. This forms inner join
If the remnants of first table is added to the common records, then it is LEFT JOIN
If remnants of right table is added to the common records ,then it is RIGHT JOIN
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9. If remnants of left and right are added to the common records, then it is FULL JOIN.
In all cases remember the appended table in mind and work out accordingly.
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