<-- Chapter 1 Introduction to SQL

SQL Syntax : SQL syntax is basically followed by sql commands which modifies the database tables such as "users" , "students" etc. All the SQL statements always starts with the keywords SELECT, INSERT, UPDATE, DELETE, ALTER, DROP, CREATE, USE, SHOW . All these statements ends with semicolon i.e ";" . In SQL statements table name plays a big role , whether table exists in the database or not.

SQL contains many commands to modify database tables.

• SELECT Statement

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

• DISTINCT Clause

SELECT DISTINCT column_name
FROM tablename;

• WHERE Clause

SELECT column1, column2....columnN
FROM tablename
WHERE CONDITION;

• AND/OR Clause

SELECT column1, column2....columnN
FROM tablename
WHERE CONDITION-1 {AND|OR} CONDITION-2;

• IN Clause

SELECT column1, column2....columnN
FROM tablename
WHERE columnname IN (value-1, value-2,...value-N);

• BETWEEN Clause

SELECT column1, column2....columnN
FROM tablename
WHERE columnname BETWEEN value-1 AND value-2;

• LIKE Clause

SELECT column1, column2....columnN
FROM tablename
WHERE columnname LIKE { PATTERN };

• ORDER BY Clause

SELECT column1, column2....columnN
FROM tablename
WHERE  CONDITION
ORDER BY columnname {ASC|DESC};

• GROUP BY Clause

SELECT SUM(columnname)
FROM tablename
WHERE CONDITION
GROUP BY columnname;

• COUNT Clause

SELECT COUNT(columnname)
FROM tablename
WHERE CONDITION;

• HAVING Clause

SELECT SUM(columnname)
FROM   tablename
WHERE  CONDITION
GROUP BY columnname
HAVING (arithmatic function condition);

• CREATE TABLE Statement

CREATE TABLE tablename(
column1 datatype,
column2 datatype,
column3 datatype,
.....
columnN datatype,
PRIMARY KEY( one or more columns )
);

• DROP TABLE Statement

DROP TABLE table_name;

• CREATE INDEX Statement

CREATE UNIQUE INDEX index_name
ON table_name ( column1, column2,...columnN);

• DROP INDEX Statement

ALTER TABLE table_name
DROP INDEX index_name;

• DESC Statement

DESC table_name;

• TRUNCATE TABLE Statement

TRUNCATE TABLE table_name;

• ALTER TABLE Statement

ALTER TABLE table_name {ADD|DROP|MODIFY} column_name {data_ype};

• ALTER TABLE Statement (Rename)

ALTER TABLE table_name RENAME TO new_table_name;

• INSERT INTO Statement

INSERT INTO table_name( column1, column2....columnN)
VALUES ( value1, value2....valueN);

• UPDATE Statement

UPDATE table_name
SET column1 = value1, column2 = value2....columnN=valueN
[ WHERE  CONDITION ];

• DELETE Statement

DELETE FROM table_name
WHERE  {CONDITION};

• CREATE DATABASE Statement

CREATE DATABASE database_name;

• DROP DATABASE Statement

DROP DATABASE database_name;

• USE Statement

USE database_name;

• COMMIT Statement

COMMIT;

• ROLLBACK Statement

ROLLBACK;