Can we use join for two different database tables?

Can we use join for two different database tables?

Asked on October 26, 2018 in Database.
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  • 5 Answer(s)

    If you have two databases on the same server – Db1 and Db2. Db1 has a table called Clients with a column ClientId and Db2 has a table called Messages with a column ClientId

    This is the query to join the above given table:

    select *
    from Db1.dbo.Clients c
    join Db2.dbo.Messages m on c.ClientId = m.ClientId
    
    Answered on October 26, 2018.
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    SELECT ...
    FROM A.table t1
    JOIN B.table2 t2 ON t2.column = t1.col
    

    This above code is used to join two different database tables

    Answered on October 26, 2018.
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    SQL Server allows you to join tables from different databases as long as those databases are on the same server. The join syntax is the same; the only difference is that you must fully specify table names.

    Let’s suppose you have two databases on the same server – Db1 and Db2Db1 has a table called Clients with a column ClientId and Db2 has a table called Messages with a column ClientId (let’s leave asside why those tables are in different databases).

    Now, to perform a join on the above-mentioned tables you will be using this query:

    select *
    from Db1.dbo.Clients c
    join Db2.dbo.Messages m on c.ClientId = m.ClientId
    
        
    Answered on January 14, 2019.
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    Sometimes it’s necessary to perform a join on two tables that are located in different databases. To do this, qualify table and column names sufficiently so that MySQL knows what you’re referring to. Thus far, we have used the artist and painting tables with the implicit understanding that both are in the cookbookdatabase, which means that we can simply refer to the tables without specifying any database name when cookbook is the default database. For example, the following statement uses the two tables to associate artists with their paintings:

    SELECT artist.name, painting.title
      FROM artist INNER JOIN painting
      ON artist.a_id = painting.a_id;

    But suppose instead that artistis in the db1 database and painting is in the db2 database. To indicate this, qualify each table name with a prefix that specifies which database it’s in. The fully qualified form of the join looks like this:

    SELECT db1.artist.name, db2.painting.title
      FROM db1.artist INNER JOIN db2.painting
      ON db1.artist.a_id = db2.painting.a_id;

    If there is no default database, or it is neither db1 nor db2, it’s necessary to use this fully qualified form. If the default database is either db1 or db2, you can dispense with the corresponding qualifiers. For example, if the default database is db1, you can …

    Answered on January 14, 2019.
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    select *
    from Db_1.dbo.Name n
    join Db_2.dbo.Marks m on n.Rollno = m.Rollno
    
    

    The above query is the syntax for join to join tables from different Database on the same server : – Db_1 and Db_2 are the two databases. Db_1 has a table called Name with a column Rollno and Db_2 has a table called Marks with a column Rollno.

    The SQL server allows us to join  tables from different database .Like wise we can also join tables on the same database on the same server.In this case we dont have to specify  the database name when  they belong to the same database.

    Answered on February 4, 2019.
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