{"id":226,"date":"2019-03-29T19:42:03","date_gmt":"2019-03-30T03:42:03","guid":{"rendered":"https:\/\/db2tutorial.com\/?page_id=226"},"modified":"2020-04-11T06:59:53","modified_gmt":"2020-04-11T14:59:53","slug":"db2-or","status":"publish","type":"page","link":"https:\/\/www.db2tutorial.com\/db2-basics\/db2-or\/","title":{"rendered":"Db2 OR"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn how to use the Db2 OR<\/code> operator to query rows that satisfy either or both predicates of the search condition.<\/p>\n\n\n\n

Introduction Db2 OR operator<\/h2>\n\n\n\n

The OR<\/code> operator is a logical operator that combines two Boolean expressions or predicates. the OR<\/code> operator is often used in the WHERE<\/a><\/code> clause of the SELECT<\/a><\/code>, UPDATE<\/a><\/code>, and DELETE<\/a><\/code> statements to specify a search condition for rows to be selected, updated, and deleted.<\/p>\n\n\n\n

Here is the syntax of the OR<\/code> operator:<\/p>\n\n\n

boolean_expression1 OR boolean_expression2\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the boolean_expression1<\/code> and boolean_expression2<\/code> are the Boolean expressions that evaluate to true, false, and unknown.<\/p>\n\n\n\n
The following table shows the result when combining true, false, and unknown values using the OR<\/code> operator:<\/p>\n\n\n\n
<\/th>TRUE<\/th>FALSE<\/th>UNKNOWN<\/th><\/tr><\/thead>
TRUE<\/strong><\/td>TRUE<\/td>TRUE<\/td>TRUE<\/td><\/tr>
FALSE<\/strong><\/td>TRUE<\/td>FALSE<\/td>UNKNOWN<\/td><\/tr>
UNKNOWN<\/strong><\/td>TRUE<\/td>UNKNOWN<\/td>UNKNOWN<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
If you use both OR<\/code> and AND<\/a><\/code> operators in an expression, Db2 always evaluates the AND<\/code> operator first. To change the order of evaluation, you can use the parentheses.<\/p>\n\n\n\n
To negate the OR<\/code> operator, you use the NOT<\/code> operator as follows:<\/p>\n\n\n
NOT (boolean_expression1 OR boolean_expression2)\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
Db2 OR operator examples<\/h2>\n\n\n\n
Let’s use the books<\/code> table from the sample database<\/a> to demonstrate the OR<\/code> operator.<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
1) Db2 OR operator example<\/h3>\n\n\n\n
This example uses the OR<\/code> operator to find the books that have the number of pages 500 or 1,000:<\/p>\n\n\n
SELECT<\/span>    \n    title, \n    total_pages\nFROM<\/span>    \n    books\nWHERE<\/span> total_pages = 500<\/span>\n        OR<\/span> total_pages = 1000<\/span>\nORDER<\/span> BY<\/span> \n    total_pages;\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
The query scans every row and returns the rows whose value in the total_pages<\/code> column is 500 or 1000.<\/p>\n\n\n\n
Here is the result set:<\/p>\n\n\n\n
\"Db2<\/figure>\n\n\n\n
Note that you can use the IN<\/code> operator to achieve the same result:<\/p>\n\n\n
SELECT<\/span>    \n    title, \n    total_pages\nFROM<\/span>    \n    books\nWHERE<\/span> \n    total_pages IN<\/span> (500<\/span>, 1000<\/span>)\nORDER<\/span> BY<\/span> \n    total_pages;\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
2) Using multiple Db2 OR operators example<\/h3>\n\n\n\n
This example uses two OR<\/code> operators to find books whose ratings are 5 and the number of pages is 500 or 1000:<\/p>\n\n\n
SELECT<\/span>    \n    title, \n    total_pages,\n    rating\nFROM<\/span>    \n    books\nWHERE<\/span> total_pages = 500<\/span>\n        OR<\/span> total_pages = 1000<\/span>\n        OR<\/span> rating = 5<\/span>\nORDER<\/span> BY<\/span> \n    total_pages;\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
Here is the output:<\/p>\n\n\n\n
\"Db2<\/figure>\n\n\n\n
3) Using Db2 OR operator with parentheses<\/h3>\n\n\n\n
If you use the OR<\/code> and AND<\/code> operators with more than two conditions, you can use parentheses to explicitly specify the evaluation order.<\/p>\n\n\n\n
The following example uses both OR<\/code> and AND<\/code> operators to find books that satisfy either of the following conditions:<\/p>\n\n\n\n
  • The number of pages is greater than 800 and less than 1,000<\/li>
  • The rating is greater than 4.7<\/li><\/ul>\n\n\n\n
    Here is the query:<\/p>\n\n\n
    SELECT<\/span>   \n    title, \n    total_pages, \n    rating\nFROM<\/span>   \n    books\nWHERE<\/span>(total_pages > 800<\/span>\n        AND<\/span> total_pages < 1000<\/span>)\n    OR<\/span> rating > 4.7<\/span>\nORDER<\/span> BY<\/span> \n    rating, \n    total_pages;\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
    The following picture shows the partial output:<\/p>\n\n\n\n
    \"Db2<\/figure>\n\n\n\n
    4) Using Db2 NOT OR operator example<\/h3>\n\n\n\n
    This example uses the NOT OR<\/code> operator to find books that have the number of pages greater than or equal 1000 and rating less than or equal 4:<\/p>\n\n\n
    SELECT<\/span>   \n    title, \n    rating,\n    total_pages\nFROM<\/span>   \n    books\nWHERE<\/span> NOT<\/span> (rating > 4<\/span> OR<\/span> total_pages < 1000<\/span>)\nORDER<\/span> BY<\/span> \n    rating desc<\/span>,\n    total_pages desc<\/span>;\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
    Here is the partial result set:<\/p>\n\n\n\n
    \"Db2<\/figure>\n\n\n\n
    Note that based on the De Morgan’s laws, NOT (A OR B) is equivalent to (NOT A AND NOT B). In this case, the following conditions are equivalent:<\/p>\n\n\n
    NOT (rating > 4 OR total_pages < 1000)\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
    and<\/p>\n\n\n
    rating <= 4 AND total_pages >= 1000)\n<\/code><\/span>Code language:<\/span> SQL (Structured Query Language)<\/span> (<\/span>sql<\/span>)<\/span><\/small><\/pre>\n\n\n
    In this tutorial, you have learned how to use the Db2 OR<\/code> operator to query rows that satisfy either or both predicates of the search condition.<\/p>\n
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