How to query oracle database

Oracle database supports multiple query methods: SQL command line query: Use tools such as SQL*Plus to execute SQL queries. Programming language interfaces: Query databases in code using APIs such as JDBC and ODBC. Database GUI: Create and execute queries using tools such as Oracle SQL Developer.

Oracle database query method

How to query Oracle database:

Oracle database supports multiple query methods, including:

1. SQL command line query:

• Open SQL*Plus or other SQL command line tools.
• Connect to the database.
• Enter the SQL query statement.
• Press Enter to execute the query.

2. JDBC, ODBC or other programming language interface:

• Use the database API in the programming language to establish a connection to the database.
• Write SQL query statements and execute queries.
• Get query results and process data.

3. Database graphical user interface (GUI):

• Open the database management tool (such as Oracle SQL Developer).
• Connect to the database.
• Use GUI tools to create and execute queries.
• View and process query results.

Sample SQL query:

The following is a sample SQL query to find all employees whose name contains "John":

<code class="sql">SELECT * FROM employees WHERE name LIKE '%约翰%';</code>

Query syntax:

Oracle query syntax follows the following structure:

<code>SELECT <列名> FROM <表名> WHERE <条件></code>

• SELECT: Specify the columns to be retrieved.
• FROM: Specifies the table from which to query data.
• WHERE: Specify query conditions to filter results.

Query options:

Oracle queries also support a variety of options, including:

• Sort: Use the ORDER BY clause to sort the results.
• Grouping: Use the GROUP BY clause to group the results.
• Aggregation functions: Use SUM, COUNT, AVG and other functions to aggregate data.
• Subqueries: Nested queries are used to get data from one query for use in another query.

The above is the detailed content of How to query oracle database. For more information, please follow other related articles on the PHP Chinese website!