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:

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

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.

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