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Unit 14: Connecting to MySQL with PHP

Notes

TO modify existing records, use UPDATE which has this form:
UPDATE table_name SET which columns to change WHERE which records to update.

Here also the WHERE clause is optional, if you don’t specify one, every records in the table is
updated.
i.e., UPDATE table_name SET which columns to change

for example you can change the specialization of a student whose roll number is 20, to etc.
from cse.
The following query fulfills the above change:

mysql>UPDATE student SET specialization=”etc” where roll_no=”20”;

After the execution of above query the contents of the table becomes:

14.2.10 Altering the Structure of Tables

Using ALTER statement you can add fields to a existing table.
The general form of ALTER statement is:

ALTER TABLE table_name ADD (column specs);

Suppose you want to add another field as marks to the student table for storing students mark.
Then the query becomes

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