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Every part has a Part Type, and every supplier is based in the US, and has a State column. There are not more than 60 states+territories in the US, and not more than 300 Part Types. The bitmap join index is defined using a standard three-table join on the three tables above, and specifying the Part_Type and Supplier_State columns for the index.
[2] [3] All details of storage are hidden from the rest of the application (see information hiding). Unit testing code is facilitated by substituting a test double for the DAO in the test, thereby making the tests independent of the persistence layer. In the context of the Java programming language, DAO can be implemented in various ways. This ...
SELECT list is the list of columns or SQL expressions to be returned by the query. This is approximately the relational algebra projection operation. AS optionally provides an alias for each column or expression in the SELECT list. This is the relational algebra rename operation. FROM specifies from which table to get the data. [3]
Internal tables are an important feature of the ABAP language. An internal table is defined similarly to a vector of structs in C++ or a vector of objects in Java. The main difference with these languages is that ABAP provides a collection of statements to easily access and manipulate the contents of internal tables.
ABAP. ABAP supports two different kinds of comments. If the first character of a line, including indentation, is an asterisk (*) the whole line is considered as a comment, while a single double quote (") begins an in-line comment which acts until the end of the line.
[3] An alternative to implementing ORM is use of the native procedural languages provided with every major database. These can be called from the client using SQL statements. The Data Access Object (DAO) design pattern is used to abstract these statements and offer a lightweight object-oriented interface to the rest of the application. [4]
For example, a table of 128 rows with a Boolean column requires 128 bytes a row-oriented format (one byte per Boolean) but 128 bits (16 bytes) in a column-oriented format (via a bitmap). Another example is the use of run-length encoding to encode a column.
This strategy has been used by ActionScript, C#, D, Java, Nemerle, Object Pascal, Objective-C, Smalltalk, Swift and PHP. [13] All these languages allow classes to implement multiple protocols. Moreover, Ada, C#, Java, Object Pascal, Objective-C, Swift and PHP allow multiple-inheritance of interfaces (called protocols in Objective-C and Swift ...