When you add two (or more) tables to a query, dbForge Studio attempts to join them based on common data or on information stored in the database about how tables are related. However, if dbForge Studio has not joined the tables automatically, or if you want to create additional join conditions between tables, you can join tables manually.
You can create joins based on comparisons between any two columns, not just columns that contain the same information.
Joins work fastest if the columns in the join condition have been indexed. In some cases, joining on unindexed columns can result in a slow query. it finds.
Add the objects you want to join to the Design Pane .
Drag the name of the join column in the first table or table-structured object and drop it onto the related column in the second table or table-structured object. You cannot base a join on text, ntext, or image columns.
The join columns must be of the same (or compatible) data types. For example, if the join column in the first table is a date, you must relate it to a date column in the second table. On the other hand, if the first join column is an integer, the related join column must also be of an integer data type, but it can be a different size. The Query and View Designer will not check the data types of the columns you use to create a join, but when you execute the query, the database will display an error if the data types are not compatible.