/* To create a new database: */ CREATE DATABASE database_name; /* Ex : */ CREATE DATABASE joes; /* To drop(Remove) a database:*/ DROP DATABASE database_name; /* Ex:*/ DROP DATABASE joes; /* To view all databases:*/ SHOW DATABASES; /* To select a database:*/ USE database_name; /* Ex:*/ USE joes; /* To create a new table:*/ CREATE TABLE users(id INT NOT NULL AUTO_INCREMENT, name VARCHAR(50) NOT NULL, age INT NOT NULL,PRIMARY KEY(id)); /* To view all tables in a database:*/ SHOW TABLES; /* To view structure of a table:*/ DESCRIBE table_name; Ex: DESCRIBE users; /* To add a new column inside a table:*/ ALTER TABLE users ADD gender VARCHAR(10) NOT NULL AFTER AGE; /* To add multiple columns to a table:*/ ALTER TABLE users ADD city VARCHAR(50) NOT NULL, ADD contact VARCHAR(50) NOT NULL; /*To modify a column in a table:*/ ALTER TABLE users MODIFY contact VARCHAR(25) NOT NULL; /*To rename a table:*/ ALTER TABLE users RENAME TO students; /*To view recoords in a table:*/ SELECT * FROM students; /* To insert a record into a table:*/ INSERT INTO students VALUES(NULL,'Ram',25,'Male','Salem','9874563210'); /* To insert mutiple records into a table:*/ INSERT INTO students(name,age,gender,city,contact) VALUES ('Ravi',23,'Male','Namakkal','9876543210'),('Sara',23,'Female','Erode','9874521360'); /* To delete a row from table:*/ DELETE FROM students WHERE id=4; /* To Modify/Update a row in table:*/ UPDATE students SET city='Hosur',contact='9988776655' WHERE id=3; /* To clear all data from a table:*/ TRUNCATE TABLE students; /* Select particular fields in a table:*/ SELECT name,age FROM students; /* elect records with criteria:*/ SELECT name,age,city FROM students WHERE city='Hosur'; /* Select recoords with multiple criteria:*/ SELECT name,age,city FROM students WHERE city='Hosur' AND age >= 23; SELECT name,age,city FROM students WHERE city='Namakkal' OR city='Hosur'; SELECT name,age,city FROM students WHERE (city='Namakkal' OR city='Hosur') AND age >= 23; /* To select unique values in a field:*/ SELECT DISTINCT city FROM students; /* To count unique values in a field:*/ SELECT COUNT(DISTINCT city) FROM students; /* To count unique values in a field with allies name:*/ SELECT COUNT(DISTINCT city) AS total FROM students; /* To Select N number of recoords:*/ SELECT * FROM students LIMIT 5; /* To Select a range of recoords:*/ SELECT * FROM students LIMIT 5,15; /* To select the very first record from a table:*/ SELECT * FROM students LIMIT 0,1; /* To select the very last record from a table:*/ SELECT * FROM students ORDER BY id DESC LIMIT 0,1; /* To select maximum value in a table:*/ SELECT MAX(age) FROM students; /* To select minimum value in a table:*/ SELECT MIN(age) FROM students; /* To select average of a field:*/ SELECT AVG(age) FROM students; /* To round a float value:*/ SELECT ROUND(AVG(age),0) FROM students; /* To select sum of a field:*/ SELECT SUM(age) FROM students; /* To select group wise records:*/ SELECT gender,COUNT(id) FROM students GROUP BY gender; /* WILD CARD QUERIES: To select values starts with some letters:*/ SELECT NAME FROM students WHERE name LIKE 'Ra%'; /* To select values ends with some letters:*/ SELECT NAME FROM students WHERE name LIKE '%am'; /* To select values contains some letters:*/ SELECT NAME FROM students WHERE name LIKE '%la%'; /* To select values having given keywords:*/ SELECT * FROM STUDENTS WHERE city IN('Salem','Namakkal'); /* To select values not having given keywords:*/ SELECT * FROM STUDENTS WHERE city NOT IN('Salem','Namakkal'); /* To select values not starts with some letters:*/ SELECT NAME FROM students WHERE name NOT LIKE 'Ra%'; /* To select values using between keyword:*/ SELECT name,age FROM students WHERE age BETWEEN 24 AND 30; /* JOIN QUERIES: 1.Inner Join(To select common values only)*/ SELECT emp.name,emp.design,salary.sdate,salray.amt FROM emp INNER JOIN salary ON emp.id = salary.id; /* 2.Left Join(To select common values and all values from the first table)*/ SELECT emp.name,emp.design,salary.sdate,salray.amt FROM emp LEFT JOIN salary ON emp.id = salary.id; /* 3.Right Join(To select common values and all values from the second table)*/ SELECT emp.name,emp.design,salary.sdate,salray.amt FROM emp LEFT JOIN salary ON emp.id = salary.id; /* To select with cases:*/ SELECT name,city,(CASE WHEN city='Salem' THEN 100 WHEN city='Namakkal' THEN 200 WHEN city='Chennai' THEN 300 WHEN city='Hosur' THEN 400 ELSE 0 END) AS amt FROM students;
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