6/19/2023 0 Comments Datagrip tutorialFor different database instances look at federation. Supported for schemas in the same database but not for different databases instances. Then prefix the table name with the database name as usual. Use the ATTACH command to add additional databases to a connection. In some situations, rather than creating separate databases you can create one database with multiple schemas that has the same effect. A schema in PostgreSQL is a namespace for objects that allow you to control ownership and permissions of its contained objects. However, if you create orders and customers as two schemas in a single database, then it does work. NOT supported by PostgreSQL if orders and customers are two databases. Make sure to include database name in table alias. Reference: SELECT syntax Use dblink to access remote servers including non-Oracle machines. References: Multiple Database Query, FROM clause syntax and specifying table aliases Below is a table with documentation references for each vendor. Every major database vendor supports this functionality. This query is identical to a query where all tables are in a single database except for providing the database name in the table alias (in bold). SELECT O.custId, C.custName, SUM(totalAmount)įROM orders.orderinfo O INNER JOIN customers.customer C ON O.custId = C.custId The query to calculate the total order amount per customer is:
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