SQL Tutorial
SQL stands for Structured Query Language is used to modify and access data or information from a storage area called Database.
History of SQL Database Design
It was introduced first by IBM in 1970s.and it is an ANSI/ISO standard. Soon it becomes a Standard Language used by relational database management systems (RDBMS) such as Oracle, Microsoft SQL server, Sybase etc.SQL is Divide in Different Languages:-
1)DML(Data Manipulation Language) – Select , Insert , Delete , Update
2)DDL (Data Definition Language)- Create, Alter, Drop
3)DCL(Data Control Language)- Grant , Revoke
SQL Database Table
Database -> IS collection of tables .Database itself to capture and analyze data
SQL Database Table Columns
Table consist of Multiple Table . Column is also know as entity.
SQL Database Table Rows
Each SQL table row, referred to a record, is located in the left column of the table. Sql record row will contain a string of data containing data matching up to each column field across the top.
SQL Select Statement
Syntax of SQL SELECT Statement:
SELECT column_listFROM table-name [WHERE Clause][GROUP BY clause][HAVING clause][ORDER BY clause];Select * from tbl_employee
Concatenate two column in Sql
Select firstname +’’+lastname from tbl_employee;
SQL Alias
Sql Alias means create second name to a column
Select firstname as First from tbl_employee
SQL Where
Where clause is use when we have to see the data depends on a condition
Select * from tbl_employee where firstname=’Nick’
Sql Operator
There are two type of operator Comparison Operators and Logical Operators. These operators are used WHERE clause, HAVING clause to filter the data to be selected.
Comparison Operators:
It is used to compare the column data with specific values in a condition.
Comparison Operators | Description |
= | equal to |
, != | is not equal to |
less than | |
> | greater than |
>= | greater than or equal to |
less than or equal to |
Logical Operators:
There are three Logical Operators namely AND, OR and NOT.i.e 1)Select * from tbl_employee where doj >=getdate();
2)Select * from tbl_emplyee where firstname=’nick’ and department=’Admin’;
SQL Comparison Keywords
There are many operator "IN", "BETWEEN...AND", "IS NULL", "LIKE".Comparision Operators | Description |
LIKE | column value is similar to specified character(s). |
IN | column value is equal to any one of a specified set of values. |
BETWEEN...AND | column value is between two values, including the end values specified in the range. |
IS NULL | column value does not exist. |
Like Operator is used to search a data that belongs to a Particular Pattern.
i.e.
1)Select * from tbl_employee where firstname like ‘%Nick%’
It will show the data whose name start with Nick
2)Select * from tbl_employee where department in(‘Admin’,’Teacher’,’Student’);
It show the data of those employee which belongs to Admin , Teacher, Student
3)Select * from tbl_employee where dob between ‘2016-01-01’ and ‘2016-07-18’;
It show the data of those employee whose dob is between ‘2016-01-01’ and ‘2016-07-18’
4)Select * from tbl_employee where department is null;
It show the data of those employee whose department is null
5)Select * from tbl_employee where department is not null;
It show the data of those employee whose department is not null
6)Select * from tbl_employee where department not in(‘Admin’,’Teacher’,’Student’);
It show the data of those employee which not belongs to Admin , Teacher, Student
SQL ORDER BY
ORDER BY clause is used in a SELECT statement to sort results either in ascending or descending order.
SELECT column-list FROM table_name [WHERE condition] [ORDER BY column1 [, column2, .. columnN] [DESC]];Select * from tbl_employee where order by firstname desc
