1. Explain the difference between BOOL, TINYINT and BIT.
Prior to MySQL 5.0.3: those are all
synonyms. After MySQL 5.0.3: BIT data type can store 8 bytes of data and should
be used for binary data.
2. 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.
3. 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.
4. What happens if a table has one
column defined as TIMESTAMP?
That field gets the current timestamp
whenever the row gets altered.
5. But what if you really want to store
the timestamp data, such as the publication date of the article?
Create
two columns of type TIMESTAMP and use the second one for your real data.
6. Explain data type TIMESTAMP DEFAULT
CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
The column exhibits the
same behavior as a single timestamp column in a table with no other timestamp
columns.
7. What does TIMESTAMP ON UPDATE
CURRENT_TIMESTAMP data type do?
On initialization places a zero in that
column, on future updates puts the current value of the timestamp in.
8. Explain TIMESTAMP DEFAULT
‘2006:09:02 17:38:44′ ON UPDATE CURRENT_TIMESTAMP.
A default value is
used on initialization, a current timestamp is inserted on update of the row.
9. If I created a column with data type
VARCHAR(3), what would I expect to see in MySQL table?
CHAR(3), since
MySQL automatically adjusted the data type.
0 comments :
Post a Comment