chapter 3

Question 1

How static embedded sql works?

Answer 1

static sql queries are embedded in the programming language, which is extended using prefix for SQL operations.
Preconversor/Precompiler converts SQL into function calls of the programming language.
Advantages: Potentially performance

Question 2

How dynamic embedded SQL works?

Answer 2

SQL queries are treated dynamically by the program. Preprocessor is still required.

Question 3

How Call-level Interface (CLI) works?

Answer 3

It has the same capabilities as dynamic embedded SQL. SQL queries are string parameters of function invocations.

Question 4

Requirement for db-gw:

Answer 4

Remote data access, multiple simultanously active DB-connections within the same applicatoin thread, simultaneous acces to multiple DBMS
ODBC x JDBC

Question 5

In the db gateway architecture, which is the role of the driver manager?

Answer 5

the driver manager is the responsible for manages interactions between applications and drivers, realizes (n:m)relationship between applications and drivers. It load/unload driver, mapping data sources to drivers, communicatation/ logginf of function/ method calls, and simple error handling.

Question 6

explain ODBC driver type: Single-Tier driver

Answer 6

Data resides on the same machine as the driver. As functionality it completes SQL processing (parse, optimize and execution) and often lacks multi-use and transaction support

Question 7

explain ODBC driver type: two-tier driver

Answer 7

Driver acts as a client interacting with DBMS (server) through data protocol

Question 8

explain ODBC driver type: three-tier driver

Answer 8

Middleware server
*gw server
*connects and relays requests to one or more DBMS servers
moves the complexity from the client to the middleware server
*client requires only a single driver for the middleware server

Question 9

Which are the JDBC driver types?

Answer 9

• type1: jdbc-odbc bridge with 2-tier.
• type 2: native-API partial-java driver, it is also 2-tier
• type3: net-protocol ALL-JAVA driver. It is 3-tier and does not requeire natie binaries on client
• type 4: native-protocol all-java driver. It is 2-tier and pure java. It implements the network data protocol of the DBMS

Question 10

WHY is SQL/OLB (SQLJ part0) a big problem to large enterprise?

Answer 10

Because in SQL/OLB there is no notion of „program“ per say. End users must have table privileges, and it is not easy to solve in a large enterprise.

Question 11

SQLJ

Answer 11

Combines advantages of embedded SQL with binary portability