|
|
|
|
|
1. |
What is default database engine for MySQL? |
| |
INODB.
|
|
2. |
what are the character data types available in MYSQL? |
| |
|
|
3. |
What happens if a table has one column defined as
TIMESTAMP? |
| |
That field
gets the current timestamp whenever the row gets
altered.
|
|
4. |
What are the optimization techniques for Query
optimization performance issues and faster execution of
queries |
| |
1.litmit
2.keys
3. indexing
|
|
5. |
What are the differences between drop a table and
truncate a table? |
| |
Drop - will
Delete the table date as well as the table structure.
Truncate - Will Delete the table data only. The table
structure will remains.
|
|
6. |
How can we change the name and data type of a column of
a
table? |
| |
To Change
DataType of Column:
Sy: Alter Table <Table Name> Modify <ColumnName> <DataType>;
Ex: Alter Table Test Modify EmpId varchar(5);
0 M. Ravindar
|
|
7. |
If
the value in the column is repeatable, how do you find
out the unique values? |
| |
Use DISTINCT
in the query, such as SELECT DISTINCT user_firstname
FROM users; You can also ask for a number of distinct
values by saying SELECT COUNT (DISTINCT user_firstname)
FROM users;
|
|
8. |
How do you convert between Unix timestamps and MySQL
timestamps? |
| |
UNIX_TIMESTAMP
converts from MySQL timestamp to Unix timestamp,
FROM_UNIXTIME converts from Unix timestamp to MySQL
timestamp.
|
|
9. |
How are ENUMs and SETs represented internally? |
| |
As unique
integers representing the powers of two, due to storage
optimizations.
|
|
10. |
How do you start and stop MySQL on Windows? |
| |
net start
MySQL, net stop MySQL
|
|
11. |
What does tee command do in MySQL? |
| |
tee followed
by a filename turns on MySQL logging to a specified
file. It can be stopped by command notee.
|
|
12. |
Can you save your connection settings to a conf file? |
| |
Yes, and name
it ~/.my.conf. You might want to change the permissions
on the file to 600, so that it’s not readable by others.
|
|
13. |
How do you change a password for an existing user via
mysqladmin? |
| |
mysqladmin -u
root -p password "newpassword"
|
|
14. |
What are some good ideas regarding user security in
MySQL? |
|
|
There is no user without a password. There is no user
without a user name. There is no user whose Host column
contains % (which here indicates that the user can log
in from anywhere in the network or the Internet). There
are as few users as possible (in the ideal case only
root) who have unrestricted access.
|
|
15. |
Explain the difference between MyISAM Static and MyISAM
Dynamic. |
|
|
In
MyISAM static all the fields have fixed width. The
Dynamic MyISAM table would include fields such as TEXT,
BLOB, etc. to accommodate the data types with various
lengths. MyISAM Static would be easier to restore in
case of corruption, since even though you might lose
some data, you know exactly where to look for the
beginning of the next record.
|
|
16. |
What are HEAP tables in MySQL? |
|
|
HEAP tables are in-memory. They are usually used for
high-speed temporary storage. No TEXT or BLOB fields are
allowed within HEAP tables. You can only use the
comparison operators = and <=>. HEAP tables do not
support AUTO_INCREMENT. Indexes must be NOT NULL.
|
|
17. |
What are CSV tables? |
|
|
Those are the special tables, data for which is saved
into comma-separated values files. They cannot be
indexed.
|
|
18. |
Explain the difference between FLOAT, DOUBLE and REAL. |
|
|
FLOATs store floating point numbers with 8 place
accuracy and take up 4 bytes. DOUBLEs store floating
point numbers with 16 place accuracy and take up 8
bytes. REAL is a synonym of FLOAT for now.
If you specify the data type as DECIMAL (5,2), what’s
the range of values that can go in this table?
999.99 to -99.99. Note that with the negative number the
minus sign is considered one of the digits.
|
