MySQL conditional query and or usage and priority example analysis

This article uses examples to illustrate the usage and priority of MySQL conditional query and or. Share with you for your reference, the details are as follows:

Introduction to mysql and and or

AND and OR can be used to combine two or more conditions in a WHERE clause.

When using the OR keyword:

• As long as one of the query conditions is met, such records will be queried.
• If any of these query conditions are not met, such records will be excluded.

When using the and keyword:

• All conditions must be met and such records will be queried.
• If any of the conditions are not met, the record will be excluded.

Mysql and and or examples

The table data needed in this example are as follows:

(1) AND condition query operator example:

Use AND to display all data with title "php array" and category 1:

SELECT * FROM ar WHERE title='php array' AND category='1'

result:

(2) OR conditional operator example

Use OR to display all data with title "java array" or seo_name "php":

SELECT * FROM ar WHERE title='java array' OR seo_name='php'

result:

(3) Combining AND and OR operators

We can also combine AND and OR (using parentheses to form complex expressions):

SELECT * FROM ar WHERE (title='java array' OR category='4')
AND seo_name='php'

result:

and and or precedence

You can include any number of and and or operators in the where clause. Without any other symbols, such as parentheses, SQL will first execute the and condition and then the or statement, such as:

select * from table from id=1 or id=2 and price>=10;
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By default, this statement executes when id=2 and price is greater than or equal to 10, or when id=1.

If you add brackets:

select * from table from (id=1 or id=2) and price>=10;

This statement executes when id=1 or id=2, and price is greater than or equal to 10.

Readers who are interested in more MySQL-related content can check out the following topics on this site: "MySQL query skills", "MySQL transaction operation skills", "MySQL stored procedure skills", "MySQL database lock related skills summary" and "MySQL common function summary"

I hope this article will be helpful to everyone's MySQL database design.