Transcript Database Testing

Oracle
Table of contents
•
•
•
•
•
•
•
What is a database?
Fundamentals of database
Table management
Inserting data
Updating data
Deleting data
Query management
–
–
–
–
–
–
–
–
–
•
•
•
•
•
•
•
•
•
•
Simple queries
Aggregate functions
String manipulation
Date manipulation
Sub queries
Equi join
Outer join
Self join
Union, intersection, minus
View management
Sequence Management
Index Management
Constraints Management
Triggers
Stored procedures
Exceptions
Sequences
Constraints
DBA features
Softsmith Infotech
Fundamentals of database
• Applications are used by end users and they enter a
group of raw data
• This data is later collated and used by management to
arrive at meaningful information
• Before we first understand the technical aspects of
database, we must understand the business data clearly
• Rule 1: In any application, first identify raw data
• Rule 2: Group related data and associate data type and
size (summary and detail)
• Rule 3: Create a set of samples for each of these groups
for better clarity
• Rule 4: Identify unique and non-unique data
• Rule 5: Identify the relationship between the data
Softsmith Infotech
Raw Data and Grouping
• Let us take railways reservation as the application
• The raw data could be
–
–
–
–
–
–
–
–
–
Passenger name
Age
Date of journey
Train name
From station
To Station
PNR number
Route codes
Stations covered in the route
• The data groups would be
• Train related data – train number, train name, route in which it is
running
• Station related data – station code, station name, station RMS
Pincode, station type (junction, station etc)
• Ticket related data – PNR Number, passenger name, date of
journey, set or berth, age, from station, to station, train code etc
Softsmith Infotech
Unique and non-unique data
• Unique data means a data that does not repeat
itself
• Station code is unique across country
• Train code is unique across country
• PNR number is unique across country
• Coach number is unique within a train, but not
unique across system
• Seat number is unique within a coach and train
• Passenger name is not unique
• Ticket price is not unique
Softsmith Infotech
Relationship between data
• One PNR number is associated with one train
code
• One PNR number is associated with one or
more passenger names
• One train code is associated with one or more
stations
• One train code is associated with one route code
• All relationships will fall under one-to-one, oneto-many, many-to-one
• Many-to-many is a combinations of the above
• We need to identify the relationships between
the data to understand clearly the dependency
between data
Softsmith Infotech
Components of database
• A physical database installation in a machine
has the following logical entities
–
–
–
–
–
–
–
–
Database (group of tables)
Tables (that contain data)
Views
Index files
Triggers
Sequences
Stored procedures (packages, functions, procedures)
Users to access the tables
Softsmith Infotech
Table Management
• Create, alter and drop are the operations on a table
• To create a table, we need to supply the table name, column names
and attributes, for each column whether it is a null or not null
column, what is the default value for that column, whether the
column is primary key or not
• CREATE TABLE is the command to be used
• When we want to add a column to a table or to change the attributes
of a column in a table, we use ALTER TABLE command
• We cannot remove a column from a table
• If we want to remove the table from the database, we need to use
DROP TABLE command
• When a table is dropped, the data is also lost
• Dual is a default built-in table to do any on the fly calculations
• The usual column data types will be number, varchar2, char, date
Softsmith Infotech
Inserting Data
• INSERT operation into a table requires data to
be entered
• We can insert all column values or selective
column values
• When insert is successful, we will get a success
message
• When we try to enter a duplicate value into a
table, we will get duplicate constraint violation
message
• During insert, if we do not supply a value, the
default value for a column is used to fill up that
column
• We can insert data only to one table at a time
Softsmith Infotech
Update Operation
• When we want to modify data in a table, we can use
UPDATE command
• We can update only one table at a time
• When we update we need to use the SET clause to set
the values for a particular column
• During update also, if try to update a record, such that it
results in duplicate record, we will get a unique
constraint violation message
• If we use update command without WHERE clause, it
will update all the records
• It is not recommended to update, without giving a where
clause
• Examples
– Update employee set salary = 1000
– Update employee set salary = 2000 where designation =
‘SALESMANAGER’
Softsmith Infotech
Delete Operation
• When we want to remove data in a table, we can
use DELETE command
• We can delete only one table at a time
• We cannot delete a particular column; it is
always one row or multiple rows
• If we use delete command without WHERE
clause, it will delete all the records
• It is not recommended to delete, without giving a
where clause
• Example
– delete from employee
– Delete from employee where designation =
‘HRMANAGER’
Softsmith Infotech
SELECT Queries
• When we want to retrieve data from a table, we
use SELECT clause
• Most of the times, testers use SELECT queries
only
• SELECT has a lot of variations and clauses.
Hence SELECT is a must for all testers
• SELECT queries can handle date and string
manipulation commands as well
• SELECT helps to filter, search and sort data
• SELECT helps to find out relationships in data
Softsmith Infotech
Simple query
• SELECT * from TRAINS
– this will get all columns in the table
• SELECT TRAIN_CODE, TRAIN_NAME from
TRAINS
– this will return only 2 columns from the table
• SELECT TRAIN_NAME from TRAINS WHERE
number_of_coaches > 15
– This is a simple filter
• SELECT TRAIN_NAME from TRAINS WHERE
number_of_coaches > 15 AND TRAIN_CODE <
100
– This is a complex filter
Softsmith Infotech
Aggregate functions
• Aggregate functions work on the whole set of
records
• SELECT max(salary) from EMPLOYEE
– this will get the maximum salary data from the table
• SELECT min(salary) from EMPLOYEE
– this will get the minimum salary data from the table
• SELECT avg(salary) from EMPLOYEE
– this will get the average salary data from the table
• SELECT count(*) from EMPLOYEE
– this will get the number of records in the table
• SELECT sum(salary) from EMPLOYEE
– this will get the sum of all salary data from the table
Softsmith Infotech
String/Numeric/Date Manipulation Functions
•
•
•
•
•
•
•
•
•
•
Lower – this will convert to lower case
Upper – this will convert to upper case
Substr – this will return a portion of the string
Soundex – will look for sounding matches
Floor – will show the lower side value
Ceil – will show the upper side value
Round – will round off the number to the nearest value
Sysdate – will show the current date
Current_timestamp – will show the current timestamp
To_date and to_char – to manipulate date formats
Softsmith Infotech
Operators
• We can use arithmetic operators like +, -, *, /
• Logical operators are AND, OR, NOT
• Open and close brackets are used to group
items
• % is used along with LIKE operator
• Where firstname LIKE ‘%raj%’ will search for raj
anywhere in firstname column
• Distinct is an operator on a column to fetch
distinct values present in all rows
• IN operator is used to provide a set of values in
the WHERE clause
• BETWEEN operator is used to provide a range
of values in the WHERE clause
Softsmith Infotech
SubQuery
• Sub query is query within a query
• This is used to ensure that the WHERE condition is
further getting values from another query
• Select employee_name, salary from employee where
designation = (select designation from positionmaster
where positioncategory like ‘%MANAGER%’)
• The innermost select is executed first and then the outer
select is executed
• In sub queries, if we use = in where condition, the
subquery must return only one value
• In sub queries, if we use IN clause in where condition,
the subquery can return more than one values
Softsmith Infotech
JOINs
• Joins are nothing but a cross product of one or
more tables
• Inner join is used to get records that match a
condition in all tables
• In joins we use alias to denote table names
• Outer join is used to get records from more than
one tables, irrespective of the condition match in
left or right table
• Example
– SELECT a.empname, b.projectname from employees
a, projects b where a.employeecode =
b.employeecode and b.projectstatus = ‘Active’
• To create outer join we use + sign to the left
table or right table
Softsmith Infotech
Union, Intersect, Minus
• Union is used to combine many SELECT
queries. The result will be all records fetched by
all queries. If 2 records match in 2 different
queries, it is printed once in the result
• Intersect is used to combine many SELECT
queries. The result will be the common records
between the 2 select queries
• Minus is used to find out the difference between
2 SELECT queries
• In all these cases, the columns selected must be
the same in all select statements
• We can use all these to find the referential
integrity of the database
Softsmith Infotech
Views
• A view is a virtual table
• A view is used to simplify a complex select
statement
• A view can bring multiple data from many tables
• For all query purposes, a view is treated as a
table
• Create View SalesPeople As Select
employeename from employees where
designation like ‘%SALES%’
• When we create views, our job to write complex
queries get reduced
Softsmith Infotech
Index Files, Transactions
• Index files are pointers to the exact location of a record
on the disk
• These help us to search faster. Hence a query executes
faster
• If we do not have index on a column, and we search
based on that column, it becomes sequential. The
performance will be poor
• Index can be unique or non-unique
• By using index files, search works as binary search
• When we do insert or update or delete, we can make
that permanent by issuing a COMMIT statement
• If we want to ignore the previous insert, update, delete
statements, we use ROLLBACK statement
Softsmith Infotech
Triggers
• Trigger is an automatic event that happens based on
insert or update or delete
• We cannot pass parameters to triggers
• A trigger can happen before or after the operation
• Create or replace trigger is used to get the trigger in
database
• :NEW.column or :OLD.column is used to retrieve internal
values when the triggers are fired
• Drop trigger is used to remove the trigger
• To test a trigger, first do the required insert or delete or
update operation on the primary table
• Do a select query on the other tables on which the
trigger operated
Softsmith Infotech
Stored Procedures
•
•
•
•
•
•
•
•
•
•
•
•
•
These are executable code written in PLSQL
These reside inside oracle
We can write loops, conditions etc including exception handling
This comes in 2 parts – package header and package body
The package header contains procedures and function definitions
The package body contains actual executable code of functions and
procedures
Procedures and functions take parameters
They must be explicitly executed and they are not automatic
Before executing procedures, set serveroutput on
Functions must return a value to the left hand side
Usually functions are used when there is only one return value or
there is a true/false returns
Inside stored procedures, people write any database queries as
required by application logic
To execute, from the prompt, give
– exec packagename.procedurename(paramaters)
Softsmith Infotech
Exceptions
• Exceptions must be handled inside stored
procedures or triggers
• This will ensure that the code does not crash
• When Others is the generic exception
• SQLCODE and SQLERRM will hold the error
number and error text
• Usually no_data_found and dup_val_on_index
are checked in most of the places
Softsmith Infotech
Cursors
• When a stored procedure needs to retrieve only one
record, we use into clause in the select statement
• When the procedure needs to process a record set, we
use cursor
• Declare the cursor and provide the select statement
• Use OPEN, FETCH and CLOSE commands to access
the cursor
• Cursorname%notfound will be set to true if there are no
more records to fetch
• Cursorname%count will provide the number of records in
the cursor
Softsmith Infotech
Sequences
• Sequences are used to generate auto
increment values
• Use Create sequence command and
provide minimum, maximum, start and
increment values
• Sequcen.nextval will provide the next
sequence number
• This can be used in any insert statements
subsequently
Softsmith Infotech
Constraints
• Not Null is a constraint while creating a
table
• Primary Key is a constraint
• Foreign Key is a constraint
• Check is a constraint to ensure that a
column has only specified values
• Unique index is also a constraing
Softsmith Infotech
DBA Features
• This list gives only the features and not detailed
information
–
–
–
–
–
–
–
–
Creating database
Creating users
Providing access rights to users across tables
Backup and restore
Crash recovery
Replication
Loading of bulk data
Partitioning of data across disks
Softsmith Infotech