oracle query maximum

How to query the maximum value in Oracle?

In Oracle database, there are many ways to query the maximum value. The following are some commonly used methods:

1. Using the MAX function

The MAX function returns the maximum value in a set of data. The usage is as follows:

SELECT MAX(column_name) FROM table_name;

Among them, column_name is the name of the column to be queried, and table_name is the name of the table to be queried.

For example, in a table named employees, if you want to query the salary of the employee with the highest salary:

SELECT MAX(salary) FROM employees;

2. Use ORDER BY and FETCH FIRST statements

ORDER BY and FETCH FIRST statements can arrange query results in a specific order and return the first few results. The usage is as follows:

SELECT column_name FROM table_name ORDER BY column_name DESC FETCH FIRST 1 ROW ONLY;

Among them, column_name is the name of the column to be queried, and table_name is the name of the table to be queried. DESC means to sort in descending order, FETCH FIRST means to return only the first row of records.

For example, in a table named products, if you want to query the products with the highest sales volume:

SELECT product_name, sales FROM products ORDER BY sales DESC FETCH FIRST 1 ROW ONLY;

3. Use subquery

Subquery It is to nest a query statement within the query statement. The usage is as follows:

SELECT column_name FROM table_name WHERE column_name = (SELECT MAX(column_name) FROM table_name);

Among them, column_name is the name of the column to be queried, and table_name is the name of the table to be queried. A subquery queries the maximum value of the same table.

For example, in a table named sales, if you want to query the region with the highest sales:

SELECT region, sales FROM sales WHERE sales = (SELECT MAX(sales) FROM sales);

The above are several ways to query the maximum value in Oracle. According to different needs and query scenarios, choosing different methods can complete the query task more efficiently.

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