SQL FAQ¶
1. Integrity constraints¶
It can be called as a declarative way in order to define a business rule for a table's cloumn.
2. Index¶
- It can be called as an optional strucure which is associalted with a table for direct access to the rows.
- Index can be created for one or more columns in table.
3. Extent¶
- It can be defined as a specific number of contigous data blocks in single allocation
- it is used to store a specific type of information
4. List the type of joins used in writing SUBQUeries¶
- Self Join
- Outer JOIN
- equi-join
5. List the various Oracle database objects¶
- Table
- views
- indexes
- Synonyms
- Squences
- TablesAces
6 Tell about to use of¶
- Rename
- Alias
- Rename:
-
It is a permanent name provide to a table or column.
-
Alias:
- It is tempory name provide to a table or column which get over after the execution of SQL statement
7. What is View?¶
- It is virtual table which is defined as a stored procedure based on one or more tables.
8. What are various components of physical databases strucure of oracle database¶
- Oracle database components of three of files
- Data Files
- Redo logo files
- control files
9. List out components of logocal database strucures of oracle database¶
- Table spaces
- Database is schema object
10. What do you mean by a tablespace?¶
- THere are logical storeage units into which a database dicied.
- It is used to group togather the related logical strucure.
11. What is a synonyms? What are its various types?¶
- A Synonym can be called as an alias for a table, view,squence or program unit.it is basically of two types.
- private: Only the owner can access it.
- Public: can be accessed by any database user
12. What are uses of synonyms?¶
- Mask the real name and owner of an object
- Provide public access to an object
- provide location transparcing for table view or program unit of a remote database.
- Siplify the SQL statements for database users
13. What do you mean by a deadlock?¶
- When two processes are waiting to update the rows of datable which are locked by another process the sitwation as called deadlock The resion of it to happen are:
- Lack of proper row lock commands
- Poor design of frontend application 0 It reduces the performances of the server servely
- There locks get automatically released automatically when a commit/rollback operation is perform or any process is killed externally