Pursuit of learning new technologies consider getting subscribed to our channel simply learn to stay updated with all the latest tech content and hit that bell icon to never miss an update from us so without any further delay let's get started with today's topic firstly let us discuss the agenda for today's session we'll start the tutorial by understanding what is sql join and then we'll discuss why we use sql join and then we'll go through different . Types of sql joins such as sql inner join sql outer join sqlf join and finally sql right join so without any further delay let us dive straight into today's topic so what is sql join in relational databases the information you want to retrieve is often stored in various different tables in such scenarios you'll need to join these tables to view data in a much better way this is where sql join comes into picture sql joins is widely used .
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Clause in s in sql essentially to combine and retrieve data from two or more tables based on related columns or you can say common fields between them now consider two tables here table one has three columns abc and three records let's say for reference we'll take them as one two three similarly table two also has three columns bcd and three records three four five here i have taken a different color combination to represent values that are Present in various columns now instead of querying each table every time to retrieve data i'll simply join these two tables and this will be the following resultant table also make sure when you're joining two tables it should compulsorily have a common column here c is the common field which forms the basis to join these two tables here why we use sql join flexibility sql join allows the user .
Access and manage records from more than one table easily let us understand with an example consider mercedes-benz which is one of the leading car manufacturers in the world and let's say they want to access the records of the customers from the database now in the database let us take they have various different kinds of tables such as customer table order table vehicle table now if they want to get the vehicle details of so and so .
Customer xyz for that they have to first query the cursor table to get the customer id now if once if they get the customer id they have to query the order table to get the order id and finally with the help of order id they can get the vehicle details now as you can see this is a time taking process and hectic at the same time now instead of that i'll just simply join these tables which will allow the users to combine rows from two or more tables based on .
Different types of conditions in this way you can access and manage your records easily data redundancy sql join allows the user to maintain data redundancy as much as low as possible so that we can maintain the amount of data anomalies that is the duplicate values that are repeated in various tables in the database finally efficiency sql join executes the query faster and shows the result much .
More quickly because instead of using various sub queries for each and every table individually we can just simply join uh two tables using a simple single query types of sql joins sql joins are broadly classified into four types they are inner join outer join left join right join and additionally we also have cross join which is not that significant uh in its usage because most of the times we use the first four joints .
Now that we have gone through different types of sql joins let us discuss each of them in detail firstly let us discuss about sql inner join sql inner join joins two tables based on a common column and selects the records that have matching values in these columns now when the condition is applied for these columns the query checks all the rows of table 1 and table 2. only the rows that satisfy the join .
Predicate are included in the resultant table let us now understand the uh syntax of the sql inner join the syntax is followed as select table one dot column one table one dot column two table do dot column one and so on from table one inner join table two on table one dot column equals to table two dot column now inner join syntax basically compares rows of table one with table two to check if any anything matches based on .
The condition provided in the on clause and when the condition is met it returns matched rows in both tables with the selected columns in the select clause let us now discuss about the sql outer join sql outer join or else it is called as sql full join or full outer join is used to get all the rows which are present in both the tables that means it will return all the records which are present in either left table that is the table 1 or the right table that is table .
2 even if there are no matching records present in both the tables let us now understand the syntax the syntax remains same that is select table 1 dot column 1 table one dot column two and so on up to table two dot column two from table one full outer join is the keyword that we use here table two on table one dot column equals to table two dot column now here you have to mention the uh the same or the similar column name in the after the on predicate statement .
Next we have sql left join left join or left outer join also known as left join results in a table containing all the rows from the table on the left side of the join that is the first table and only the rows that satisfy the join condition from the table on the right side of the join that is the second table any missing values for the rows from the right table in the result of the join tables are represented by null values let's look at .
The syntax the syntax is followed as select column list that is the column that you want to uh display in your table now make sure you maintain the uh syntax of the column list that is the table name dot column name otherwise it will throw an error so let me just repeat the syntax the syntax is select column list from table one the keyword that we use here is left join table two on table one dot column equals to table two dot column .
So in this way you can use the left join to display the records next finally we have the uh sql right join now right join or right outer join is opposite to that of the left outer join now it follows the same rules as the left join and the only difference is that all the rows from the right table and only the conditions satisfying the rows from the left table are present in the resultant table that means it will .
Return all the rows from the right table and all the matching records that are present in the left table the syntax remains the same that is select column list that you want to display in your table from table 1 write join is the keyword we use table 2 on table 1 dot column equals to table two dot column now to sum up all these different sql joins and how they work i've taken a graphical representation of two different tables here which will help us .
Visualize the real time working of sql joins now consider table one here which is columns a and b and records uh two different records let's say record zero record one and similarly we have table two which have uh columns a and c and two records that is record zero and record two now if you apply left join and by the definition of left join it will only uh return those values which will which are present in the left table and the matching records that are .
Present in the right table now here the uh matching value that are present in both the tables is zero and they require values that are present in the left table is one and if you consider the right join it will match the request from both the tables and it will display the only the values from the right table that is the reason it is being displayed uh the record zero and the record two and if you look at the inner join it .
Will match uh the values from both the tables now the common value that is present in both the tables is record 0 and if you finally look at the outer join it will record it will return all the values from both the tables irrespective if they are matching or not that is the reason all the records that is record 0 record 1 and record 2 are being displayed and with that we have come to the end of .
Today's session that was all about sql joins stay tuned for more upcoming videos veren will execute all these types of joints in mysql workbench using various examples thank you for watching the video guys i hope you found this tutorial useful and informative if you have any further queries regarding any of the topics covered in the uh tutorial feel free to let us know in the comment section below and a team of experts will be more than happy to resolve all your .
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