Question

I am using SQL Server 2008 Enterprise with Windows Server 2008 Enterprise. I have a database table called “Book”, which has many columns and three columns are important in this question, they are

• Author, varchar;
• Country, varchar;
• Domain, varchar.

I want to write a store procedure with the following logics, but I do not know how to write (because of complex query conditions), appreciate if anyone could write a sample for me?

Input parameter: p_author as varchar, p_country as varchar, and p_domain as varchar

Query conditions:

1. if p_author is specified from input, then any row whose Author column LIKE %p_author% is satisfied with condition, if p_author is not specified from input every row is satisfied with this condition;
2. if p_country is specified from input, then any row whose Country column = p_country is satisfied with condition, if p_country is not specified from input every row is satisfied with this condition;
3. if p_domain is specified from input, then any row whose Domain column LIKE %p_domain% is satisfied, if p_domain is not specified from input every row is satisfied with this condition;

The results I want to return (must met with all following conditions):

• records met with either condition 1 or 2;
• records must meet with condition 3;
• return distinct rows.

For example, records which met with condition 1 and condition 3 are ok to return, and records which met with condition 2 and condition 3 are ok to return.

thanks in advance,
George

Answer 1

If I understand correctly, the following should work:

 SELECT * 
FROM Books
WHERE (
   ((Author LIKE '%' + @p_author + '%' OR @p_author = '') OR 
   (Country LIKE '%' + @p_country + '%' OR @p_country = ''))
   AND (@p_author <> '' OR @p_country <> '')
) AND 
(Domain LIKE '%' + @p_domain + '%' OR '%' @p_domain = '')