FAQs(226 to 240)

226) What is a precompiler?

A) It is a DB2 facility for static SQL statements - it replaces these statements with calls to the DB2 language interface module.

227) What is a root page?

A) The opposite of a leaf page; it is the highest level index page. An index can contain only the one root page; all other index pages are associated to the root.

228) What is a thread?

A) A thread is the connection between DB2 and some other subsystem, such as CICS or IMS/DC.

229) Which transaction use a command thread ?

A) Only the DSNC transaction uses a command thread.

230) What is the purpose of the DSNC transaction ?

A) The DSNC transaction is used for controlling the CICS Call Attach Facility(CAF) and for Displaying CAF statistics.

231) When is the authorization check on DB2 objects done - at BIND time or run time?

A) At run time.

232) What is auditing?

A) Recording SQL statements that access a table. Specified at table creation time or through alter.

233) max number of columns in a db2 table

A) 224

234) I need to view the number of tables existing under one particular Owner. Is it possible? If so, pl give the SQL query for this?

A) The query SELECT * FROM SYSIBM.SYSTABLES WHERE CREATOR = 'owner id' This displays the table names with that If you want only the number of tables give the following query. SELECT COUNT(*) FROM SYSIBM.SYSTABLES WHERE CREATOR = 'owner id' Make sure that you are in correct subsystem.

235) I need to view the number of tables existing under one particular Owner. Is it possible? If so, pl give the SQL query for this?

A) The query SELECT * FROM SYSTABLES WHERE OWNER= should work.

236) I need to view the number of tables existing under one particular Owner. Is it possible? If so, pl give the SQL query for this?

A) Db2 records information for its operation in a catalog which is actually a group of tables. So we can use the SYSTABLES to get answer to ur query.

237) What is JOIN and different types of JOIN.

A) The ability to join rows and combine data from two or more tables is one of the most powerful features of relational system. Three type of joins:1. Equi-join 2.Non-equijoin 3.self-join

238) can I alter a table (e.g. adding a column) when other user is selecting some columns or updating some columns from the same table?

A) yes possible. until the updation or selection is committed db2 table will not be restructured. new column definition will be there but it will not be included until all the tasks on the table are committed.

239) How many sub queries can you combine together ?

A) Total 16 queries and sub queries are 15

240) What are the different methods of accessing db2 from tso? How is the connection established between TSO & DB2?

A) There are three ways in establishing tso/db2 connection 1. SPUFI 2. QMF 3. CATALOG VISIBILITY B. A thread between TSO & DB2 is established while attempting to make connection between tso & db2.