According to the query of PHP Chinese website, in SQL query, the WHERE clause is used to filter out records that meet specific conditions. It defines the target of the query and which data rows to retrieve from the database. WHERE clause plays a very important role in SQL query, because it determines which columns are selected and returned as query results. By using the WHERE clause, you can filter out records that don't meet certain conditions and only get rows that meet your needs. These conditions can be a combination of operators, such as equal to, unequal to, greater than, less than, within a certain range, etc. A that is used to filter specific fields of the query. Therefore, in SQL query, WHERE clause is used to specify query conditions, that is, to filter out records that meet specific conditions, thus realizing the definition of query objectives.