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>Copy after loginDescription:
- 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>Copy after loginSelect "order_id" from the "orders" table , "customer_id" and "total_amount" columns:
<code>SELECT order_id, customer_id, total_amount FROM orders;</code>Copy after loginSelect all employees with "name" starting with "J" from the "employees" table:
<code>SELECT name FROM employees WHERE name LIKE 'J%';</code>Copy after loginSelect from the "products" table Products sorted in descending order by "price":
<code>SELECT * FROM products ORDER BY price DESC;</code>Copy after loginThe 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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