Question

my table schema as follows:

                      +------+-------+-------+                                                                                                                                                         
                      | id   | name1 | name2 |                                                                                          
                      +------+-------+-------+                                                                                        
                      |    1 | A     | B     |
                      |    2 | A     | C     |
                      |    3 | B     | A     |
                      |    4 | C     | D     |
                      +------+-------+-------+

and i am using the query as follows:

          select * from t where name1='A' or name1='B' and name2='C';

and the result as follows

                       +------+-------+-------+
                       | id   | name1 | name2 |
                       +------+-------+-------+
                       |    1 | A     | B     |
                       |    2 | A     | C     |
                       +------+-------+-------+

How this result came and

I want the query which returns the row that in which the name1 will be A or B and name2 to be ‘B’

the query result should be like this

                       +------+-------+-------+
                       | id   | name1 | name2 |
                       +------+-------+-------+
                       |    1 | A     | B     |
                       +------+-------+-------+

I want the result from the query using only “AND” and “OR” operation…

Answer 1

I suggest you read up about boolean logic. This is a very simple operation, so if you were familiar with B.L., you’d have been able to do this yourself.

That being said, these two states will accomplish what you want:

SELECT ... WHERE (name1 IN ('A', 'B')) AND (name2 = 'B')
SELECT ... WHERE ((name1 = 'A') or (name1 = 'B')) AND (name2 = 'B')