Function of select statement in oracle

The SELECT statement can retrieve data from Oracle tables. Functions include: Data retrieval: Select data from a column. Column selection: Specify the columns to retrieve or use (*) to retrieve all columns. Calculation: Perform calculations and return results, such as sums or averages. Conditional filtering: Use the WHERE clause to filter results by condition. Sorting: Use the ORDER BY clause to sort the results by column. Grouping: Use the GROUP BY clause to group results by columns and aggregate data. Join: Use the JOIN clause to join data from multiple tables.

Function of SELECT statement in Oracle

The SELECT statement is the core in Oracle for retrieving data from a table Order. It allows you to select specific columns or calculated values ​​and filter the results by specific criteria.

Function:

• Data retrieval: Select and retrieve data for specific columns from the table.
• Column Selection: Specify specific columns to retrieve, or use an asterisk (*) to retrieve all columns.
• Calculation: Perform calculations and return results, such as sums, averages, or counts.
• Conditional filtering: Use the WHERE clause to filter results by specific conditions.
• Sort: Use the ORDER BY clause to sort the results by the specified column.
• Grouping: Use the GROUP BY clause to group results by specified columns and aggregate data (such as a sum or average).
• Join: Use the JOIN clause to join data from multiple tables.

Structure:

<code>SELECT <列列表>
FROM <表名>
[WHERE <条件>]
[GROUP BY <列列表>]
[HAVING <条件>]
[ORDER BY <列列表>]</code>

Usage:

To use the SELECT statement, enter the following steps:

1. Specify the column name or asterisk (*) to retrieve.
2. Specify the data source table (FROM clause).
3. Optional: Add conditions using the WHERE clause to filter the results.
4. Optional: Use the GROUP BY clause to group the results, and use the HAVING clause to add grouping conditions.
5. Optional: Use the ORDER BY clause to sort the results.

The above is the detailed content of Function of select statement in oracle. For more information, please follow other related articles on the PHP Chinese website!