The command keyword for querying data in SQL is SELECT, which is used to extract specific columns or records from a database table. The SELECT statement structure includes: SELECT [DISTINCT]
FROM [WHERE
][ORDER BY ][LIMIT ]
Keywords for query commands in SQL: SELECT
Keywords for querying data in SQL The words are SELECT. It is used to extract specific columns or records from database tables.
SELECT statement structure:
<code class="sql">SELECT [DISTINCT] <要提取的列名> FROM <表名> [WHERE <过滤条件>] [ORDER BY <排序列>] [LIMIT <返回记录数>]</code>Copy after loginSELECT statement elements:
- DISTINCT: Used to exclude duplicate records.
- Column name to extract: Specify the column to be obtained from the table.
- FROM: Specify the table to query.
- WHERE: Specify filter conditions to filter out records that meet specific conditions.
- ORDER BY: Specify the column by which the results will be sorted.
- LIMIT: Specify the number of records to return.
Example:
The following statement queries the names and email addresses of all customers from the
Customerstable:<code class="sql">SELECT Name, Email FROM Customers;</code>Copy after loginThe following statement queries the product names and prices with a price greater than 100 from the
Productstable:<code class="sql">SELECT Name, Price FROM Products WHERE Price > 100;</code>Copy after loginThe following statement queries all orders in the past 30 days from the
Orderstable , and sorted by date in descending order:<code class="sql">SELECT * FROM Orders WHERE OrderDate >= DATE('now', '-30 days') ORDER BY OrderDate DESC;</code>Copy after loginThe above is the detailed content of The keywords of query commands in sql are. For more information, please follow other related articles on the PHP Chinese website!
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