What is the command to implement selection operation in sql
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- 2024-05-07 05:24:15916browse
Select data commands in SQL: The SELECT command extracts data from specific rows and columns from a table. Specific syntax: SELECT
FROM [WHERE
][ORDER BY [ASC|DESC]]
Commands for selection operations in SQL: SELECT
The SELECT command is used to extract data for specific rows and columns from a database table.
Syntax:
<code>SELECT <列名列表> FROM <表名> [WHERE <条件>] [ORDER BY <列名> [ASC|DESC]]</code>Description:
- Column name list: Specify the The extracted columns can use a single column name or multiple column names.
- Table name: Specify the table from which to extract data.
- WHERE clause: Can be used to filter results based on specific criteria.
- ORDER BY clause: Can be used to sort the results by the specified column. ASC means ascending order, DESC means descending order.
Example:
Select all columns from the "customers" table:
<code>SELECT * FROM customers;</code>Select "order_id" from the "orders" table , "customer_id" and "total_amount" columns:
<code>SELECT order_id, customer_id, total_amount FROM orders;</code>Select all employees with "name" starting with "J" from the "employees" table:
<code>SELECT name FROM employees WHERE name LIKE 'J%';</code>Select from the "products" table Products sorted in descending order by "price":
<code>SELECT * FROM products ORDER BY price DESC;</code>The above is the detailed content of What is the command to implement selection operation in sql. For more information, please follow other related articles on the PHP Chinese website!
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