Embed Size (px)
Citation preview
Second session
SQL language
Data type
Select statement
Objectives
SQL language
DCLDMLDDL
• select• Insert• Delete• update
• create• drop• Alter• truncat
e
• grant• Revoke• deny
DML• data manipulation language (DML) In a database
management system (DBMS), a language that is used to insert data in, update, delete and query a database.• DML is used to manipulate the data of a database.
•Ex: Select, Update, insert, delete
Data Manipulation Language (DML)
• is the language element that allows you to use the• core statements SELECT ,INSERT, UPDATE, DELETE to manipulate data in
any SQL Server tables. Core DML statements include the following: • SELECT: Retrieves rows from the database and enables the selection of one or many rows or columns from one or many tables in SQL Server. • INSERT: Adds one or more new rows to a table or a view in SQL Server. • UPDATE: Changes existing data in one or more columns in a table or view. • DELETE: Removes rows from a table or view.
Data Definition Language• DDL statements are used to build and modify the structure of
your tables and other objects in the database. When you execute a DDL statement, it takes effect immediately
Create - To make a new database, table, index, or stored procedure. Drop - To destroy an existing database, table, index, or view. Alter - To modify an existing database object.
Data Control Language• DCL is abbreviation of Data Control Language. It is used to create
roles, permissions as well it is used to control access to database by securing it.• Examples: GRANT, REVOKE statements GRANT command is used by administrators to add new permissions to a database user. REVOKE command is used to remove database access from a user previously After we know SQL statement what is Transaction Control Language .. ??
Data Types Data types specify the type of data that you work with in a program. The data type defines the size of memory needed to store the data and the kinds of operations that can be performed on the data.
Why data types are important• Using the wrong data type can cause large performance
degradation in the database and can lead to data corruption.• Using the wrong data type can cause the database to use
significantly more storage than needed, which is wasteful.
Exact numeric
Approximate numerics
Character StringsThe DateTimeOffset data type is similar to the DateTime data type, but it also keeps track of time zones.• Char(size)—Holds a fixed-length string. The fixed size is
specified in parentheses. Holds a maximum of 8,000 characters.
• Varchar(size)—Holds a variable-length string. The maximum size is specified in parentheses. Holds a maximum of 8,000 characters.
• Text—Holds a variable-length character string. Maximum size is 2 GB of text data.
Unicode Character Strings
Binary Strings
CREATE TABLE
• CREATE TABLE table_name(column_name1 data_type,column_name2 data_type,column_name2 data_type,...)
create table employees( id int, emp_name varchar(50), address varchar(50))
Recap of SQL Queries• A query in SQL can consist of up to six clauses, but only the first two, SELECT
and FROM, are mandatory. The clauses are specified in the following order:• Allows users to retrieve specific information from the database.
SELECT <attribute list>FROM <table list>[WHERE <condition>][GROUP BY <grouping attribute(s)>][HAVING <group condition>][ORDER BY <attribute list>]• There are three SQL commands to modify the database: INSERT, DELETE,
and UPDATE
Select statement syntax :
OperatorsOperators :
BETWEEN – Range of valueLIKE – To find a name contaning specific characterIN – Set of values
Like :
select * from employees where emp_name like 'a%'select * from employees where emp_name like '%d'select * from employees where emp_name like 'nabil'select * from employees where emp_name like '_abil' in :
SELECT * FROM employees WHERE emp_Name IN ('ahmed','ali')
between :
SELECT * FROM ProductsWHERE Price BETWEEN 10 AND 20;
INSERT
INSERT INTO table_nameVALUES (value1,value2,value3,...);
insert into employees values (1,‘mones','nasr city')
INSERT INTO table_name (column1,column2,column3,...)VALUES (value1,value2,value3,...);
INSERT INTO employees (emp_name) VALUES ( 'moo');
Alter
To add a new column to a table :
ALTER TABLE table_name ADD column_name datatype
ALTER TABLE employees ADD DateOfBirth date
To change structure of an existing column :
ALTER TABLE table_name ALTER COLUMN column_name datatype
ALTER TABLE employees ALTER COLUMN DateOfBirth year
DropTo remove an existing databaseDROP DATABASE database_name
DROP DATABASE Sales;
To remove an existing table from a databaseDROP TABLE table_name DROP TABLE ProductVendor1 ;
To drop coulmnALTER TABLE table_name DROP COLUMN column_name
ALTER TABLE employees DROP COLUMN Id;
Try this select * from employeesupdate employees set salary= 700 where emp_name like 'a%‘
create table alltypes( id int, firstname varchar(50), postcode varchar(50), email varchar(50), gender varchar(50), tel numeric(18,0) )
We need to select all employees who take salary more than $3,000 from the employees table.
SELECT *FROM employeesWHERE salary> 3000
insert into alltypes values( 100,'Mohammad','ZPR02D','[email protected]','Male','0205468712',28/4/1973,45000,2500.00 )
Mahmoud mones [email protected]
