Some basic SQL (structured query language) queries are regarding how to be more efficient and productive as you have to have a detailed knowledge of how to use the structure of the database for it to be useful. Queries generally involve basic formatting of the system and how to use it.
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Placeholders in an abstraction layer such as PDO in PHP allows for caching and security in database queries (they fight SQL injection).
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: Has the ability to include metadata from many sources. Reduce the number of database constraints 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: All relevant query subjects are optimized for performance. You can utilize SQL that is specific to the database you are using. Disadvantages: You cannot use SQL that the data source does not support for sub queries. 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: You can use any SQL supported by the database. Disadvantages: Framework manager does not have the ability to automatically optimize performance. In some cases, the SQL won't function with another data source.
The DDL provides statement for the creation and deletion of tables, indexes, views etc. The DML provides statements to enter, update, delete and perform complex queries on these tables.
The basic parts of a SQL Select query are: SELECT column names FROM table name WHERE conditions ORDER BY column names The basic parts of an insert query would be: INSERT INTO table name (VALUES) The basic parts of a delete query would be DELETE FROM table name WHERE conditions The basic parts of an update query would be UPDATE TABLE table name SET column name = value WHERE conditions
There are many purposes behind 'SQL' data types. The most common use of 'SQL' is with website programming and hosting services, as well as HTML coding.