Sharing of data filtering methods in MySQL

MySQL is one of the most commonly used relational database management systems at present. It provides a variety of data filtering methods to obtain the required data from the database. This article will share commonly used data filtering methods in MySQL for readers’ reference and learning.

1. WHERE statement

The WHERE statement is the most basic and commonly used data filtering method in MySQL. It filters out the required data from the table based on specified conditions. For example:

SELECT * FROM table_name WHERE column_name = value;

Among them, table_name is the name of the table that needs to be queried, column_name is the name of the column that needs to be filtered, and value is the value that needs to be filtered. This statement will return all data in the table_name table where the column_name column value is equal to value.

The WHERE statement can also use other conditional operators, such as greater than (>), less than (751326d5701d796a469715c2f454b724=), less than or equal to (dc4dee774ac85135ff75b969197272e4), less than (751326d5701d796a469715c2f454b724=), less than or equal to (<=), not equal to (! =), LIKE, etc.

5. LIMIT statement

The LIMIT statement is used to limit the number of rows returned by query results. For example:

SELECT * FROM table_name LIMIT 10;

Among them, table_name is the name of the table to be queried, and LIMIT 10 means that only the first 10 rows of data are returned. This statement will return the first 10 rows of data in the table_name table.

The LIMIT statement can also specify the starting position and number of rows of the returned data, for example:

SELECT * FROM table_name LIMIT 10 OFFSET 20;

This statement will start from row 21 in the table_name table and return 10 rows of data.

6. DISTINCT keyword

The DISTINCT keyword is used to return query results after deduplication. For example:

SELECT DISTINCT column_name FROM table_name;

Among them, table_name is the name of the table that needs to be queried, and column_name is the name of the column that needs to be deduplicated. This statement will return all the values ​​in the column_name column in the table_name table after deduplication.

7. IN keyword

The IN keyword is used to specify a list of values ​​and return query results that satisfy any value in the list. For example:

SELECT * FROM table_name WHERE column_name IN (value1, value2, value3);

Among them, table_name is the name of the table that needs to be queried, column_name is the name of the column that needs to be filtered, and value1, value2, and value3 are the values ​​that need to be matched. This statement will return all data in the table_name table whose column_name column matches any one of value1, value2, and value3.

8. NOT IN keyword

The NOT IN keyword is the opposite of the IN keyword, returning query results that do not satisfy any value in the list. For example:

SELECT * FROM table_name WHERE column_name NOT IN (value1, value2, value3);

Among them, table_name is the name of the table that needs to be queried, column_name is the name of the column that needs to be filtered, and value1, value2, and value3 are the values ​​that need to be matched. This statement will return all data in the table_name table where the column_name column does not match any value among value1, value2, and value3.

The above are commonly used data filtering methods in MySQL. Different method combinations can be selected in different scenarios. Readers can use it flexibly according to actual needs to improve the efficiency and accuracy of data filtering.

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