Filtering data with conditions

It is quite common to narrow down the result set by using a condition clause, such as LIMIT, WHERE, IN/NOT IN, and EXISTS/NOT EXISTS. The LIMIT keyword limits the specified number of rows returned randomly. Compared with LIMIT, WHERE is a more powerful and generic condition clause to limit the returned result set by expressions, functions, and nested queries as in the following examples:

> SELECT name FROM employee LIMIT 2;
+----------+
|   name   |
+----------+
| Lucy     |
| Michael  |
+----------+
2 rows selected (71.125 seconds)
  

> SELECT name, work_place FROM employee WHERE name = 'Michael'; 
+----------+------------------------+ 
| name     | work_place             | 
+----------+------------------------+ 
| Michael  | ["Montreal","Toronto"] | 
+----------+------------------------+ 
1 row selected (38.107 seconds)

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