Primary Key and Foreign Key in MySQL Explained with Examples | MySQL Tutorial

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[gauravpathak]

01:27 Primary key and foreign key constraints in relational databases

02:54 Creating a primary key in a database for unique identification

04:21 Foreign key creates linking between two tables

05:48 Foreign keys link the primary keys of two tables, enabling joint operations.

07:15 Creating a students table with primary and foreign keys

08:42 Creating a city table with id as primary key and city_id as foreign key

10:09 City ID 522 is located in city ID 609

11:29 Enforcing primary key and foreign key constraints is crucial in large-scale relational databases.

[namanshah]

bahut achhe se samjaya sir aapne 😊❤
lekin Email id toh Unique nhi hota hai na sir ?
😊😊

[vinaymishra]

sir great work I had search more then 10 tutorials to find this concept but now it is clear

[rabh-bo]

Sir table banai hai lekin bol rha hai referencing column city_id and referenced column cities (id)is incompatible.😢

[RajeshKumar-jxql]

city_id kisi or table ki primary key hone wali kyu hoga???? jbki kisi or table me to already primary ki hmne de rakhi h

[technicalrider]

Wrong teaching u have add primary key to city_id if ur refering city_id primary key to foreign key (cid)

[nikhilmore]

PRIMARY KEY is parent
(confirm on other sources)

[theAdam]

5. What is a foreign key? Write a query to implement the same in MySQL.

This is one of the prevalent MySQL queries interview questions for both beginner and experienced candidates. A foreign key is used to connect two tables. A FOREIGN KEY is a field (or assortment of it) in one table that alludes to the PRIMARY KEY in another table. The FOREIGN KEY requirement is utilised to forestall activities that would crush joins between tables.

To assign a foreign key, it is important to mention it while creating the table. It can be assigned by invoking the FOREIGN KEY query. Something like this:

FOREIGN KEY (Any_ID) REFERENCES Table_to_reference(Any_ID)

[rabh-bo]

Jinka error aa rha ho vo cities ki table me primary key (Id) rakhe phrr chal jayega.

[manyadewangan]

I have a good doubt sir if we use primary key while creating columns then unique constraint ka koi use nhi hoga?

[Akagarkar]

kodular ya thunkable per ek video upload kijiye sir please

[coolanujkumar]

missing index for constraint .... in the referenced table

[bhaveshmorankar]

failed to add the foreign key dikha raha hai isko kaise solve kre?

[lion]

Error Code: 1822. Failed to add the foreign key constraint. Missing index for constraint

[shakmaangaming]

failed to add misssing constraints error aa rha hai sir g??

[shelkeonka]

Sir 3 br try Kara laekin failed to add missing constraints error araha hai

[shubhamnimbalkar]

yedee chale mat kar aaise portion tu bad mai sikha raha hai student ko ...primary key foreign key pahile sikhana tha....time wast