Recently, I spent a lot of time working with SQL on the AS/400 and IBM i power system. With my background in cranking out the background of traditional physical and logical file DDS, I do not see the need for change until I really dig in and understand how SQL is implemented on i.
And the writing is on the wall for DIY ... plus there are features available by using SQL DDL to define your database and create a beat DDS capabilities. It is time for some SQL objects that you create will end up on the deck platform.
Often people who come to me to contact IBM outside of the file that has several members. Basically your database a "member" as part of the additional tables that use the same column structure, but data between the member is treated as a separate creation.
It's almost like the two tables to be treated in the same way as an object defined on the system. By using the native application you can easily access secondary members. But with SQL there is no direct way to do it. To get what you use to make a statement referring to the ALIAS specified file member. This creates a logical file that data requests from members who built on.
Subsequent visits. The views were honestly is one of the coolest features of the use of SQL. You build up a view of the data you want to see and how you want it, which is a big advantage. You can build the data that casts an eye or summarize column format ... basically anything that can be used as a kind of select statement is executed, it can be permanently built with the help of the eye.
Views can be very useful for users that third-party data reporting tools to exploit the system. You can set certain standards and reporting scheme for mining only the data they want and use the label to state that will make it easier to read the description column.
In view of the IBM ia created as a non-typed logical file. This means that the system is not subject to any access roads to maintain or overhead as traditional logical file type is built using DDS specification. The downside to the view that it is evaluated at runtime and questioned, so it may be the fastest way to get data records.
Finally, you will eventually need to build the index. Create index type logical file on the system. If you write a program type of RPG you will eventually index for things like chains and Reade operations in your code. Index helps speed up data retrieval and records since they made the access point system. This can be a double-edged sword.
Of course you have to use wisely and indexes when evaluating the possibility to create an index on the whole image. Build indexes shave a minute or two late assignment report may not be near as important to shave seconds off the screen input is used all day every day.
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