content_image/842986.jpg content_image/842987.jpg content_image/842988.jpg content_image/842989.jpg
The UPDATE  changes only the record in question and does not require you to reload the table. 

There is an exception to the principle that SELECT *  selects all columns. If a table contains invisible columns, *  does not include them. For more information, see Section 13.1.20.10, “Invisible Columns” . 

## 3.3.4.2 Selecting Particular Rows 

As shown in the preceding section, it is easy to retrieve an entire table. Just omit the WHERE  clause from the SELECT  statement. But typically you don’t want to see the entire table, particularly when it becomes large. Instead, you’re usually more interested in answering a particular question, in which case you specify some constraints on the information you want. Let’s look at some selection queries in terms of questions about your pets that they answer. 

You can select only particular rows from your table. For example, if you want to verify the change that you made to Bowser’s birth date, select Bowser’s record like this: 

mysql> SELECT * FROM pet WHERE name = ’Bowser’; 

<img src='content_image/842986.jpg'>

The output confirms that the year is correctly recorded as 1989, not 1979. 

String comparisons normally are case-insensitive, so you can specify the name as ’bowser’ , ’BOWSER’ , and so forth. The query result is the same. 

You can specify conditions on any column, not just name . For example, if you want to know which animals were born during or after 1998, test the birth  column: 

mysql> SELECT * FROM pet WHERE birth >= ’1998-1-1’; 

<img src='content_image/842987.jpg'>

You can combine conditions, for example, to locate female dogs: 

mysql> SELECT * FROM pet WHERE species = ’dog’ AND sex = ’f’; 

<img src='content_image/842988.jpg'>

The preceding query uses the AND  logical operator. There is also an OR  operator: 

mysql> SELECT * FROM pet WHERE species = ’snake’ OR species = ’bird’; 

<img src='content_image/842989.jpg'>

AND  and OR  may be intermixed, although AND  has higher precedence than OR . If you use both operators, it is a good idea to use parentheses to indicate explicitly how conditions should be grouped: 

