1. Structured Query Language (SQL)

2. SQL Non-Procedural Structured Query Language.(4GL) Data Sub language.
Developed by IBM in the late 1970’s.
In 1986, the ANSI made SQL as standard for all RDBMS.
SQL does not support any programming language constructs like if…else OR do…while.
SQL can be embedded in other programming languages like C, COBOL.
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3. Features of SQL SQL is a non-procedural language.
SQL is used for all types of Database activities by all ranges of users including,
System administrators.
Database administrators.
Application Programmers
End users.
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4. Data Definition Language (DDL) Data Manipulation Language (DML)
DBMS LANGUAGES
Data Definition Language (DDL)
Creating & Altering the structure of the database.
Data Manipulation Language (DML)
Insert, Update & Delete.
Data Control Language (DCL)
Controlling access to the database(Grant,Revoke)
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5. Transaction Control … COMMIT, ROLLBACK
Data Retrieval … SELECT
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6. DATA TYPES SUPPORTED IN SQL
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7. Tables used :
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8. Data Retrieval Using SQL*PLUS
SQL*PLUS provides a query capability in the form of SELECT statement.
One can view the current information in the tables by using this statement.
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9. 5 parts of basic SQL query
SELECT – list the columns you want
… (more than one table, use table.field)
FROM – list of tables used
WHERE – selection/join criteria (opt)
GROUP BY – how to summarize (opt)
ORDER BY – sorting order (opt)
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10. SELECT Command Displaying some OR all the columns from a table.
SELECT <col1, col2, … .> OR <*>
FROM <table_name> ;
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11. List the Department table. 1.
SELECT * FROM Dept ;
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12. List the Department table. List the Department table
A Better Way! 2.
List the Department table.
List the Department table
SELECT Deptcode, Deptname, Deptmanager, Deptbudget
FROM Dept ;
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13. SELECT Deptmanager, Deptname FROM Dept ;
Only Some Columns 3.
List all department managers with the names of their department
SELECT Deptmanager, Deptname FROM Dept ;
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14. WHERE Predicate ( = ) 4. SELECT Empname, Deptcode FROM Emp
List all employees of the Accounts department.
SELECT Empname, Deptcode
FROM Emp
WHERE Deptcode = ‘Acct’ ;
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15. WHERE Predicate ( < )5.
List all officers.
SELECT Empname, Gradecode
FROM Emp
WHERE Gradecode < 10 ;
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16. Date Comparison 6. SELECT Empname, Birthdate FROM Emp
List all young employees.
SELECT Empname, Birthdate
FROM Emp
WHERE Birthdate > ‘01-Jan-70’ ;
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17. SELECT DISTINCT deptcode FROM emp ;
Eliminating Redundant Data
DISTINCT is an argument that provides a way for you to eliminate duplicate values.
e.g.
SELECT DISTINCT deptcode FROM emp ;
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18. Use of Boolean operators
1. SELECT * FROM emp
WHERE Basicpay >= AND Basicpay <= 4500 ;
2. SELECT * FROM emp
WHERE Desigcode = ‘Engg’ OR Basicpay > 3000 ;
3. SELECT empname FROM emp
WHERE NOT deptcode = ‘Acct’ ;
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19. In Operator
IN operator can be used to select rows that match one of the values included in the list.
1. SELECT empname FROM emp
WHERE deptcode IN(‘Acct’, ‘Pers’) ;
2. SELECT empname FROM emp
WHERE deptcode NOT IN(‘Acct’, ‘Pers’) ;
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20. Between construct
Defines a range that values must fall into make the predicate true.
List all middle level staff
List all middle level staff
SELECT Empname, Gradecode
FROM Emp
WHERE Gradecode BETWEEN 10 AND 15;
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21. Like construct Used for pattern searching.
Pattern consists of characters to be matched & the wildcard’ characters.
WildCard chars. Matches
_ (under score) Any single character.
% Any sequence of zero or more characters.
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22. Like construct List all employees with UMA in their names
SELECT Empname
FROM Emp
WHERE Upper(Empname) LIKE ‘%UMA%’ ;
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23. Null values
List the employees who have not been assigned to any supervisor
SELECT Empname, Supcode
FROM Emp
WHERE Supcode IS NULL ;
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24. Compound Predicate - Interval
List the female employees who have just completed 5 years
SELECT Empname, Sex, Joindate
FROM Emp
WHERE Sex = “F”
AND Joindate BETWEEN(sysdate - 5*365)
AND (sysdate - 6*365) ;
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25. Predicate using OR
List employees who are either 50 years or more or have more
than 20 years experience.
SELECT EmpName
FROM Emp
WHERE BirthDate < (sysdate - 50*365)
OR JoinDate < (sysdate - 20*365) ;
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26. Parentheses in Predicate
List foremen who are either 50 years or more or have more than
20 years experience.
SELECT EmpName
FROM Emp
WHERE DesigCode = ‘FRMN’
AND ((BirthDate < (sysdate - 50*365)
OR JoinDate < (sysdate - 20*365));
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27. Expressions in SELECT List
List 1% of take-home pay of all employees.
SELECT Empcode, (Basic + Allow -Deduct ) * 0.01
FROM Salary
WHERE SalMonth = ‘1-Mar-97’;
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28. EMPCODE (BASIC+ALLOW-DEDUCT) * 0.01
17 rows selected.
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29. Aliasing List the present age of all the employees. SELECT EmpName,
TRUNC(SYSDATE - BirthDate) / 365) AGE
FROM Emp ;
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30. Ltitl/Trng/Sql/V1.0

31. For getting the resultant rows in a specified order.
Order By
For getting the resultant rows in a specified order.
Ascending order is default.
List all employees ordered by age
SELECT EmpName, TRUNC(SYSDATE - BirthDate)/365 AGE
FROM Emp
ORDER BY BirthDate ;
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32. Ltitl/Trng/Sql/V1.0

33. Sorting Ascending / Descending
List middle level staff according to seniority
List middle level staff according to seniority
SELECT EmpName, GradeCode, GradeLevel
FROM Emp
WHERE GradeCode BETWEEN 10 AND 25
ORDER BY GradeCode, GradeLevel DESC ;
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34. Ltitl/Trng/Sql/V1.0

35. Sorting by Result of Expression
List all according to age and seniority
List middle level staff according to seniority
SELECT EmpName, TRUNC(SYSDATE - BirthDate/365) AGE,
GradeCode, GradeLevel
FROM Emp
ORDER BY 2 DESC, GradeCode, GradeLevel DESC ;
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36. Ltitl/Trng/Sql/V1.0

37. AGGREGATE Functions
Act on a group or set of rows and return one row of summary information per set.
SUM Computes the total value of the group.
AVG Computes the average value of the group.
MIN Computes the minimum value of the group.
MAX Computes the maximum value of the group
COUNT Counts the no. of NON-NULL values for the specified group.
COUNT(*) Counts the no. of rows including those having NULLvalues for the given condition.
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38. AGGREGATE Functions Count employees reporting to Singh.
SELECT COUNT(*)
FROM Emp
WHERE Supcode = ‘7844’ ;
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39. GROUP BY - Aggregate Functions
The grouping of rows is achieved by using the GROUP BY clause.
Allows you to define a subset of the values in a particular field in terms of another field, and apply an aggregate functions to the subset.
Enables you to combine fields and aggregate functions in a single SELECT statement
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40. GROUP BY - Aggregate Functions
List the number of staff reporting to each supervisor.
SELECT Supcode, COUNT(*)
FROM Emp
GROUP BY Supcode
ORDER BY Supcode ;
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41. GROUP BY - Sum SELECT EmpCode, SUM(Basic + Allow - Deduct) PAY
List the total take-home pay during for all employees.
SELECT EmpCode,
SUM(Basic + Allow - Deduct) PAY
FROM Salary
WHERE SalMonth BETWEEN ‘1-Apr-96’
AND ‘31-Mar-97’
GROUP BY EmpCode
ORDER BY EmpCode ;
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42. Ltitl/Trng/Sql/V1.0

43. GROUP BY - Max & Min List the maximum & minimum salaries in grades.
SELECT GradeCode, MAX(Basic), MIN(Basic)
FROM Grade
GROUP BY GradeCode
ORDER BY GradeCode ;
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44. Ltitl/Trng/Sql/V1.0

45. HAVING
Defines criteria used to eliminate certain groups from the output, just as the WHERE clause does for individual rows.
HAVING can take only arguments that have a single value per output group.
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46. HAVING List the number of staff reporting to each supervisor
having more than 3 people working under them.
SELECT SupCode, COUNT(*)
FROM Emp
GROUP BY SupCode
HAVING COUNT(*) > 3
ORDER BY SupCode ;
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47. Where - Group By - Having
List the total take-home pay during for all
employees getting a total take-home-pay < Rs
SELECT EmpCode, SUM(Basic + Allow - Deduct) PAY
FROM Salary
WHERE SalMonth BETWEEN ‘1-Apr-96’ AND ‘31-Mar-97’
GROUP BY EmpCode
HAVING SUM(Basic + Allow - Deduct)
ORDER BY EmpCode ;
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48. Where - Group By - Having
List the maximum and minimum basic salary in
each grade for grades with start < Rs. 4000
SELECT GradeCode, MAX(Basic), MIN(Basic)
FROM Grade
GROUP BY GradeCode
HAVING MIN(Basic) < 4000
ORDER BY GradeCode ;
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49. Joining Table
The process of forming rows from two or more tables by comparing the contents of related cloumns is called ‘Joining Tables’.
Joins are the foundation of multi-table query processing in SQL.
Syntax :
SELECT <col1,col2,...>
FROM <table_name>
WHERE <logical expr.> ;
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50. Joining Table - Types of Joins
Equi-Join
Cartesian Join
Self Join
Outer Join
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51. Natural Join - Equi-Join
Check the basic salary of all employees.
SELECT EmpCode, EmpName, Grade.Basic,Emp.Basic
FROM EMP, GRADE
WHERE Emp.GradeCode = Grade.GradeCode
AND Emp.GradeLevel = Grade.GradeLevel ;
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52. Self Join Match and retrieve rows that have a matching value in
different cloumns of the same table.
List employees along with the names of their supervisors
SELECT E.Empname, S.EmpName Supervisor,
FROM EMP E, EMP S
WHERE E.SupCode = S.EmpCode ;
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53. Cartesian Join
A cartesian product matches every row of one table to every row of the other table.
e.g.
SELECT EmpName, DeptName
FROM EMP, DEPT
WHERE DesigCode = ‘clerk’ ;
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54. Outer Join
Retrieving selected rows from one table that don’t match rows in the other table.
To find department names & the employees in them,
as well as those departments which do not have
employees in them
SELECT DeptName, EmpName
FROM EMP, DEPT
WHERE EMP.DeptCode(+) = DEPT.DeptCode ;
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55. SELECT SupCode, COUNT(*) FROM EMP WHERE GradeCode < 10
List the number of officers reporting to each supervisors
having more than 3 people working under them.
SELECT SupCode, COUNT(*)
FROM EMP
WHERE GradeCode < 10
GROUP BY SupCode
HAVING COUNT(*) > 3 ;
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56. Nested Queries ( Subquery )
Placing a query inside the predicate of another query, and using the inner query’s output in the predicate’s true or false condition.
Subqueries divided into two groups.
1. Single-Row Subquery
Returns only one value to the outer query.
2. Multi-Row Subquery
Returns multiple values to the outer query
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57. SELECT EmpName FROM EMP WHERE DesigCode = (SELECT DesigCode FROM EMP
Single-Row Subquery
To find out all the employees who have the same job as ‘scott’.
SELECT EmpName FROM EMP
WHERE DesigCode = (SELECT DesigCode FROM EMP
WHERE EmpName = ‘scott’) ;
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58. WHERE DeptCode = (SELECT DeptCode FROM DEPT WHERE DeptName = ‘sales’);
Single-Row Subquery
To list the names of all employees working in sales dept; assuming that dept no. of sales dept is not known.
SELECT EmpName
FROM EMP
WHERE DeptCode = (SELECT DeptCode
FROM DEPT
WHERE DeptName = ‘sales’);
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59. SELECT EmpName, DesigCode, Salary FROM EMP WHERE DeptCode = 20 AND
Multi-Row Subquery
List the name, job and salary of people in dept 20 who have the same job as people in dept. 30.
SELECT EmpName, DesigCode, Salary
FROM EMP
WHERE DeptCode = 20 AND
DesigCode IN (SELECT DesigCode FROM EMP
WHERE DeptCode = 30) ;
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60. Multiple levels of Nesting
Find name, job and salary of people in dept 20 who have the same job as people in the sales dept.
SELECT EmpName, DesigCode, Salary
FROM EMP WHERE DeptCode = 20
AND DesigCode IN (SELECT DesigCode FROM EMP
WHERE DeptCode = (SELECT DeptCode
FROM DEPT WHERE DeptName = ‘sales’) ;
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61. Subqueries returning Multiple values
Find out who are the highest paid employees in each dept.
SELECT DeptCode, EmpName, Salary
FROM EMP
WHERE (DeptCode, Salary)
IN (SELECT DeptCode, MAX(Salary)
GROUP BY DeptCode) ;
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62. EXISTS Operator output or not.
Used to base a predicate on whether a subquery produces
output or not.
EXISTS is an operator that produces a True or False value.
It takes a subquery as an argument and evaluates to True if
it produces any output or false if it does not.
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63. e.g. To list data from customer table if and only if
one or more of the customers in the customers
table are located in ‘San Jose’.
Select cnum, cname, city From customer
Where Exists
(Select * From customer
Where city = ‘San Jose’) ;
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64. EXISTS Operator SELECT * FROM DEPT A WHERE EXISTS (SELECT * FROM EMP B
To list all department details from Dept. table which has atleast one employee.
SELECT * FROM DEPT A
WHERE EXISTS (SELECT *
FROM EMP B
WHERE B.DeptCode = A.DeptCode) ;
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65. insert into tablename [(col1, col2, …)] values (exp1, exp2, …);
Inserting rows of data
insert into tablename [(col1, col2, …)]
values (exp1, exp2, …);
If the col names are not listed, the data is assigned to all cols in order
To insert only into certain cols, name them
… cols not named are given null values
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66. INSERT one complete row
INSERT INTO HISTORY
VALUES
(‘7369’, ‘01-Aug-96’, ‘SLMN’, ‘12’, 5000) ;
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67. INSERT one partial row INSERT INTO EMP (EmpCode, EmpName, Basic)
Employ Hussein as a temporary employee.
INSERT INTO EMP
(EmpCode, EmpName, Basic)
VALUES
(‘9123’, ‘Hussein’, 250) ;
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68. INSERT thru Subquery INSERT INTO SALARY
Update the SALARY table for the month.
INSERT INTO SALARY
SELECT EmpCode, trunc(Sysdate, mon), Basic,
Basic*1.5, Basic*0.3
FROM EMP ;
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69. Delete one row DELETE FROM EMP WHERE EmpCode = ‘7934’ ;
Delete employee record of Kaul.
DELETE FROM EMP
WHERE EmpCode = ‘7934’ ;
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70. Bulk Delete DELETE FROM EMP WHERE DeptCode = ‘FLNG’ ;
Delete all employee records of Filing Department.
DELETE FROM EMP
WHERE DeptCode = ‘FLNG’ ;
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71. Delete entire Table DELETE FROM SALARY ;
Delete the entire SALARY Table.
DELETE FROM SALARY ;
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72. Update one Row UPDTAE EMP SET GradeCode = ‘4’, DesigCode = ‘MNGR’,
Promote Gupta as Manager (Exports)
UPDTAE EMP
SET GradeCode = ‘4’,
DesigCode = ‘MNGR’,
Basic = 15000
WHERE EmpCode = ‘7654’ ;
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73. Bulk Update UPDTAE DEPT SET DeptBudget = DeptBudget * 1.25
Raise the budget by 25% for all the departments
except Facilities department.
UPDTAE DEPT
SET DeptBudget = DeptBudget * 1.25
WHERE DeptCode != ‘FACL’ ;
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74. CREATE TABLE tablename (colname datatype [default value] [colconstrt]
Creating a table with SQL
CREATE TABLE tablename
(colname datatype [default value] [colconstrt]
… tblconstraint, …, tblconstraint)
[TABLESPACE tablespacename];
Only one primary key per table (mult cols OK)
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75. default 50 – use 50 if no value is given Column constraints:
Constraint examples
default 50 – use 50 if no value is given
Column constraints:
…not null (default is to allow nulls)
…check condition
…unique
…primary key
…references tblname [colname]
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76. (p is precision, s is scale) VARCHAR2(p) – variable length string
Common datatypes
(p is precision, s is scale)
VARCHAR2(p) – variable length string
…… p can be 1 to 4000
NUMBER(p,s) - p is # of digits
…… s is # of decimal digits (like Fortran)
DATE time, many possible formats
… from 1/1/4712 BC to 12/31/4712 AD
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77. CHAR(p) – older fixed length format
… p from 1 to 255, pads with blanks
LONG – variable length text string to 2G
… use is limited in queries
LOB – replacing LONG, up to 4G (video)
…”Large Object Block”
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78. DDL for Table Dept Create table dept
( Deptcode char(4) constraint dept_pk primary key,
Deptname char(25) not null,
Deptmanager char(6),
Deptbudget number not null );
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79. DDL for Table Emp Create table emp
( Empcode char(6) constraint emp_pk primary key,
Empname char(20) not null,
Deptcode char(4) constraint emp_dept_rc references
dept(deptcode) ,
Birthdate date not null,
Joindate date not null,
Sex char(1) not null
check(sex in(‘M’, ‘F’)),
Desigcode char(4) not null
constraint emp_desig_rc references desig(desigcode)
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80. Contd...
Supcode char(6) constraint emp_sup_rc references emp(empcode),
Gradecode number(2),
Basic number(5)) ;
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81. DDL for Table Grade Create table grade ( Gradecode number(2) not null,
Gradelevel number not null,
Basic number(5) not null,
constraint grade_pk primary key(Gradecode, Gradelevel) ;
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82. … (ROLLBACK cannot restore this) DROP removes the table definition
To remove a table
DROP TABLE tablename
… (ROLLBACK cannot restore this)
DROP removes the table definition
DELETE just removes the rows
it leaves the table
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83. Alter table Best to get your tables correct the first time
But if alteration is needed, you can:
… add a new column
… change a column’s definition
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84. alter table customers add (fax char(12),
Example adding new columns
alter table customers add (fax char(12),
ctype char(1) check(ctype in (‘I’,’B’)));
Cannot add a new column as not null
… it starts out all null (empty)!
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85. Alter table customers modify ( street varchar2(50));
Example modifying a column
Alter table customers modify ( street varchar2(50));
Can increase (not decrease) width
Restrictions also exist on changes to:
… datatypes and constraints (cur violated)
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86. Views - Creation View can be used as if it is a table.
View is a logical table based on one or more tables.
View can be used as if it is a table.
View does not contain data of their own.
Whenever a view is accessed, the query is evaluated. Thus view is dynamic.
Any changes made in the view affect the tables on which the view is based.
View helps to hide the ownership details of a table and complexity of query used to retrieve data, from the user.
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87. Views - Creation Create a view for Employee-Age.
CREATE VIEW EMPAGE (EmpCode, Age) AS
(SELECT EmpCode, TRUNC((SYSDATE - BirthDate)/365)
FROM EMP) ;
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88. Views - Creation Create a view for Employee-Pay.
CREATE VIEW EMPPAY (EmpCode, NetPay, SalMonth) AS
(SELECT EmpCode, (Basic + Allow - Deduct), SalMonth
FROM SALARY) ;
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89. Use of Views List employees who are older than their supervisors.
SELECT E.EmpCode, EmpName
FROM EMP E, EMPAGE A
WHERE E.EmpCode = A.EmpCode
AND age > (SELECT Age FROM EMPAGE
WHERE E.SupCode = EmpCode ) ;
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90. Commit
Makes permanent all changes made since last Commit or since the beginning of the user’s session.
Syntax :
COMMIT [work] ;
work - is optional & only provided for readability.
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91. RollBack Syntax : ROLLBACK [work] ;
RollBack undoes all the changes that has been done since the last commit or last Rollback or the named savepoint.
Syntax :
ROLLBACK [work] ;
ROLLBACK TO Savepoint <savepoint_name> ;
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92. Savepoint Savepoint <savepoint_name> ;
Savepoint helps in breaking a transaction into parts.
Useful if only a part of changes made are to be discarded.
If the name of an existing savepoint is reused, the old savepoint is erased.
Commit or Rollback without any parameters will erase all savepoints.
Rollback To Savepoint will undo all changes made after the Savepoint.
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