ALTER Command Tutorial in PHP

Features of MySQL ALTER Command :

1) Add Column in a Table

2) Changing Data Type of a Column

3) Change Column Name

4) Adding Constraints to a Column

5) Changing Column Position

6) Delete Column

7) Renaming Tables


ALTER Syntax :

1) For Add Column :

ALTER TABLE table_name ADD column_name datatype;

2) For Modify Column :

ALTER TABLE table_name MODIFY column_name datatype;

3) For Delete Column :

ALTER TABLE table_name DROP COLUMN column_name datatype;

4) For Rename Column :

ALTER TABLE table_name CHANGE column_name New_name datatype;

5) For Rename Table :

ALTER TABLE table_name RENAME new_table_name;


If we want to Add Extra Column named "Email" in table named "students" then we can use below shown sql query :

ALTER TABLE students ADD Email varchar(100);


If we want to place "Email" column after "name" column then in "students" table then we can use below shown sql query :

ALTER TABLE students MODIFY Email varchar(100) AFTER name;


If we want to change data type of column named "Email" in "students" table then we can use below shown sql query :

ALTER TABLE students MODIFY Email INT(10);


If we want to apply UNIQUE value to Column named "Email" in table named "students" then we can use below shown sql query :

ALTER TABLE students ADD UNIQUE(Email);


If we want to change the name of column named "Email" in table named "students" then we can use below shown sql query :

ALTER TABLE students CHANGE Email Email_id varchar(100);


If we want to delete column named "Email_id" from table named "students" then we can use below shown sql query :

ALTER TABLE students DROP COLUMN Email_id;


If we want to change the table name from "students" to "students_make" then we can use below shown sql query :

ALTER TABLE students RENAME students_make;


If we want to add new records from any particular Index in column For Example, if we want to add new records in column from Index 4 then we can use below shown sql query :

ALTER TABLE students AUTO_INCREMENT = 4;

Comments

Post a Comment

Popular posts from this blog

GROUP BY Clause and HAVING Clause in PHP

GROUP BY :  The GROUP BY clause is used in conjunction with the SELECT Statement and Aggregate functions to group rows together by common column values. SELECT with GROUP BY Syntax : SELECT columns FROM table_name WHERE condition GROUP BY column_name(s); (Here above "condition" is Optional in above query). In "personal" table, there are 6 columns named id, name, percentage, age, gender, city. In "personal" table, column name "id" is PRIMARY KEY and column name "city" is FOREIGN KEY. In "courses" table, there are 2 columns named course_id and course_name. In "courses" table, column name "course_id" is PRIMARY KEY. In "city" table, there are 2 columns named cid and cityname. In "city" table, column name "cid" is PRIMARY KEY. SELECT with GROUP BY with Two Tables Syntax : SELECT columns FROM table1 INNER JOIN table2 ON table1.column_name = table2.column_name WHERE condition GROUP B...
Read more

Method Overriding in Traits in PHP

Image
  <?php class Base {     public function abc ()     {         echo "ABC method from Base class." ;     } } //The trait method(Here, abc() Method) will get priority compared to Parent class Method(Here, abc() Method) trait Test {     public function abc ()     {         echo "ABC method from test trait." ;     } } class Child extends Base {     use Test ;     public function abc ()     {         echo "ABC method from Child class." ;     } } $obj = new Child (); $obj -> abc ();
Read more

Mysqli database Connection and Display Table Data from Database

  <?php $servername = "localhost" ; $username = "root" ; $password = "" ; $dbname = "heer" ; $conn = new mysqli ( $servername , $username , $password , $dbname ); if ( $conn -> connect_error ) {     die ( "Connection Failed : " . $conn -> connect_error ); } $sql = " SELECT * FROM student " ; $result = $conn -> query ( $sql ); if ( $result -> num_rows > 0 ) {     while ( $row = $result -> fetch_assoc ())     {         echo "<pre>" ;         echo "Id: { $row ["id"]} - Name: { $row ["name"]} - Age: { $row ["age"]} - Phone No: { $row ["phone"]} - City: { $row ["city"]}" ;         echo "</pre>" ;     } } else {     echo "No result fount" ; } $conn -> close (); //  OUTPUT: //Id: 0 - Name: Raj - Age: 25 - Phone No: 9854233621 - City: Ahmedabad // Id: 1 - Name: Amit - Age: 22 - Phone No: 8533...
Read more