How many type of SQL?

Answer 1

There are three types of SQL:

1.	Cognos SQL

2.	Native SQL

3.	Pass-through SQL

Cognos SQL

Framework Manager generates Cognos SQL in a more efficient manner in order to keep its functionality. It is common for Cognos SQL to be translated into Native SQL before being transmitted to the database for processing. Some actions or functions may not be supported by the database in some instances. Only a portion of the Cognos SQL is transmitted to the database in these situations. As a result, the database handles part of the query and the Cognos server handles the rest.

Advantages:

1. Has the ability to include metadata from many sources.

2. Reduce the number of database constraints

3. Interact more effectively with Cognos applications.

Disadvantages:

You cannot use non standard SQL.

Native SQL

Databases such as Oracle, SQL Server, and DB2 all support SQL. Using Native SQL in a model query subject with many data sources is not possible.

Advantages:

1. All relevant query subjects are optimized for performance.

2. You can utilize SQL that is specific to the database you are using.

Disadvantages:

1. You cannot use SQL that the data source does not support for sub queries.

2. The query subject may not be compatible with different database types.

Pass-through SQL

Allows the usage of Native SQL without regard to the limitations imposed on subqueries by the data source. Subqueries are not processed in Pass-Through SQL query subjects. It is instead supplied directly to the data source that generates query results for each subject.

It is important to keep in mind that pass-through SQL is delivered straight to the data source rather than being optimized by the Framework Manager, therefore performance will be lower than with the other query options.

Using curly brackets around your SQL statement in a Tabular SQL object causes that SQL statement to be passed through to the database. Cognos has not validated this SQL, so take that into consideration.

Step1: Create a Tabular SQL object. Write a statement surrounded with { }.

Actual:

SELECT * FROM ORDER HEADER

Pass-Through:

{SELECT * FROM ORDER HEADER}

Advantages:

1. You can use any SQL supported by the database.

Disadvantages:

1. Framework manager does not have the ability to automatically optimize performance. In some cases, the SQL won't function with another data source.

Answer 2

native sql,

cognos sql,

pass-through sql