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In mysql, you can use the select statement with the WHERE clause to query the specified condition, the SELECT statement is used to read the data, the WHERE clause is used to set the conditional read data, and the syntax is "select field list from table name where conditional statement".

The operating environment of this tutorial: windows10 system, mysql8.0.22 version, Dell G3 computer.

How to query a specified condition by mysql

Use SQL SELECT statements to read data from the MySQL table.

To conditionally select data from a table, you can add a WHERE clause to the SELECT statement.

I. definition

Use the where clause to filter the data in the table and output the filter results.

II. Grammar

Select field list from table name where statement

III. Classification

1. Filter by relational operator

Equal to =

Greater than >

Greater than or equal to > =

Less than 10 and name=' Zhang San'# query data with age greater than 10 and name equal to "Zhang San". Select * from student where not name=' Zhang San'# # query data whose name is not equal to "Zhang San".

3. Scope query

In

Between large value and decimal value

Examples are as follows

Select * from student where age in (10, 10, 11) # # query data with age equal to 10 or 11. Select * from student where age=10 or age=11 # # is equivalent to the above statement. Select * from student where age between 10 and 24 # # queries data with age between 10 and 24, including boundary values.

4. Empty judgment

Select * from student where address is null # # query data whose address is null select * from student where address is not null # # query data whose address is not null

5. Fuzzy query

Like

% represents any number of characters (including 0)

_ represents any character

Escape: cancel wildcard properties for% or _ characters

Examples are as follows

Select * from student where name like 'Wang%' # query the data surnamed Zhang in name. Select * from student where name like 'Zhang _ # # query the data of two words surnamed Zhang in name. Select * from student where name like'% A%% 'escape' A' # query the data containing "%" in name. These are all the contents of the article "how to query specified conditions in mysql". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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