COMPUTER GENERATION

Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to distinguish between varying hardware technologies. But nowadays, generation includes both hardware and software, which together make up an entire computer system. There are totally five computer generations known till date. Each generation has been discussed in detail along with their time period and characteristics. Here approximate dates against each generations have been mentioned which are normally accepted. 

Following are the main five generations of computers Generation & Description.

1. First Generation
The period of first generation: 1946-1959. Vacuum tube based.
2. Second Generation
The period of second generation: 1959-1965. Transistor based.
3.Third Generation
The period of third generation: 1965-1971. Integrated Circuit based.
4.Fourth Generation
The period of fourth generation: 1971-1980. VLSI microprocessor based.
5.Fifth Generation
The period of fifth generation: 1980-onwards. ULSI microprocessor based

Various Syntax in SQL

Various Syntax in SQL 
All the examples given in this tutorial have been tested with a MySQL server.

SQL SELECT Statement 

SELECT column1, column2....columnN
FROM table_name;

SQL DISTINCT Clause

SELECT DISTINCT column1, column2....columnN
FROM table_name;

SQL WHERE Clause 
SELECT column1, column2....columnN
FROM table_name
WHERE CONDITION;

SQL AND/OR Clause 
SELECT column1, column2....columnN
FROM table_name
WHERE CONDITION-1 {AND|OR} CONDITION-2;

SQL IN Clause
SELECT column1, column2....columnN
FROM table_name
WHERE column_name IN (val-1, val-2,...val-N);

SQL BETWEEN Clause 
SELECT column1, column2....columnN
FROM table_name WHERE column_name
BETWEEN val-1 AND val-2;

SQL LIKE Clause 
SELECT column1, column2....columnN
FROM table_name
WHERE column_name LIKE { PATTERN };

SQL ORDER BY Clause 
SELECT column1, column2....columnN
FROM table_name
WHERE CONDITION
ORDER BY column_name {ASC|DESC};

SQL GROUP BY Clause
SELECT SUM(column_name)
FROM table_name
WHERE CONDITION
GROUP BY column_name;

SQL COUNT Clause 
SELECT COUNT(column_name) FROM table_name
WHERE CONDITION;